Today's Message Index:
----------------------
1. 05:02 AM - Re: lan tracer (bob noffs)
2. 05:02 AM - Re: lan tracer (bob noffs)
3. 07:12 AM - Re: lan tracer (Robert L. Nuckolls, III)
4. 08:20 AM - Re: Comm Antenna & SWR: More Information (Robert L. Nuckolls, III)
5. 08:22 AM - Re: Comm Antenna & SWR: More Information (Robert L. Nuckolls, III)
6. 08:26 AM - Re: Graphene (Robert L. Nuckolls, III)
7. 03:32 PM - Re: coax antenna cable length (Noel Loveys)
8. 03:49 PM - Re: Comm Antenna & SWR: More Information (Don)
9. 04:05 PM - Re: Comm Antenna & SWR: More Information (Don)
10. 04:05 PM - Re: Comm Antenna & SWR: Grounding the Ground Plane: Ref: Bob N's. Message 27 Posted on 1-25-11 (Noel Loveys)
11. 04:07 PM - Re: Comm Antenna & SWR: More Information (Noel Loveys)
12. 04:26 PM - Re: Comm Antenna & SWR: More Information (Noel Loveys)
13. 04:26 PM - Re: Comm Antenna & SWR: More Information (Noel Loveys)
14. 04:44 PM - Re: Graphene (Noel Loveys)
15. 05:28 PM - Re: Comm Antenna & SWR: More Information (BobsV35B@aol.com)
16. 06:34 PM - Re: coax antenna cable length (Robert L. Nuckolls, III)
17. 06:46 PM - Re: Comm Antenna & SWR: More Information (Robert L. Nuckolls, III)
18. 06:53 PM - Re: Comm Antenna & SWR: More Information (Robert L. Nuckolls, III)
19. 07:43 PM - Re: Comm Antenna & SWR: More Information (Don)
20. 08:18 PM - Re: Comm Antenna & SWR: More Information (Robert L. Nuckolls, III)
21. 08:26 PM - Re: Comm Antenna & SWR: More Information (Robert L. Nuckolls, III)
22. 08:57 PM - Comm Antenna & SWR: More Questions... (David Lloyd)
Message 1
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thanks bob,
anyone have a tracer they can recommend? one of the trackers on this
wedsite is the one i bought [one with long black antenna] from harbour
freight. purely worthless. when i called the tech guy to make arrangements
to ship it back he ''checked something'' then came back on the phone and
said just toss it and he would give me credit. on my card. also, the gb i
have been looking at is on one of these sites at a great price but i have
read that it works and that it doesn't. any feedback from a trusted
aerolectric follower would be appreciated.
bob noffs
On Wed, Jan 26, 2011 at 9:42 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:01 PM 1/26/2011, you wrote:
>
> hi all,
> anyone have any experience with a wire tracer that they can recommend one?
> under $ 60 i hope.
> bob noffs
>
>
> How about these?
>
> *http://tinyurl.com/49bj2pa*
>
> *http://tinyurl.com/4hnlvvh*
>
> Bob . . .
>
> *
>
> *
>
>
Message 2
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thanks bob,
anyone have a tracer they can recommend? one of the trackers on this
wedsite is the one i bought [one with long black antenna] from harbour
freight. purely worthless. when i called the tech guy to make arrangements
to ship it back he ''checked something'' then came back on the phone and
said just toss it and he would give me credit. on my card. also, the gb i
have been looking at is on one of these sites at a great price but i have
read that it works and that it doesn't. any feedback from a trusted
aerolectric follower would be appreciated.
bob noffs
On Wed, Jan 26, 2011 at 9:42 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 10:01 PM 1/26/2011, you wrote:
>
> hi all,
> anyone have any experience with a wire tracer that they can recommend one?
> under $ 60 i hope.
> bob noffs
>
>
> How about these?
>
> *http://tinyurl.com/49bj2pa*
>
> *http://tinyurl.com/4hnlvvh*
>
> Bob . . .
>
> *
>
> *
>
>
Message 3
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At 07:57 AM 1/27/2011, you wrote:
>thanks bob,
> anyone have a tracer they can recommend? one of the trackers on
> this wedsite is the one i bought [one with long black antenna] from
> harbour freight. purely worthless. when i called the tech guy to
> make arrangements to ship it back he ''checked something'' then
> came back on the phone and said just toss it and he would give me
> credit. on my card. also, the gb i have been looking at is on one
> of these sites at a great price but i have read that it works and
> that it doesn't.
You could build one. They function based on the
simple-ideas that drive the occasional need for
shielded wire. Electro-Static Coupling.
The 'transmitter' is usually a two-transistor
multi-vibrator or perhaps an IC audio amplifier
set up as an oscillator. The goal is to generate
a square-wave at about 400-1000 hz that has
VERY fast rise and fall times. In other words,
very high harmonic content. A 9v battery, two
transistors, 4 resistors and 4 capacitors would
do the trick.
The receiver is nothing more than a high gain
audio amplifier with a capacitive probe . . .
a metallic tip that can be placed in close
proximity to the wire ends being explored
for 'continuity'.
Capacitive coupling through the insulation
of the excited wire will come across as the
400-1000 Hz audio note. In fact, your probe is
really detecting the much higher frequency
harmonics that couple across the insulation
modulated at the audio rate.
Failure to function for any such product can
be a combination of factors. Edges of the
square wave are too slow. Amplifier in probe
is too low in gain. Receiver electronics poorly
shielded for the effects of other noises not
impressed through the probe.
These things appear really easy to make work
and they are. But it's a bit like learning
to make biscuits. Just having the ingredients
and a rough notion of how they go together
is not a recipe for success. There are
subtle but critical design goals to be
met.
I've seen some chatter on the DIY sites
suggesting that a transistor AM pocket radio
can be jeeped into a really good detector.
The transistor oscillator isn't a big deal
either.
Bob . . .
Message 4
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| Subject: | Re: Comm Antenna & SWR: More Information |
>
>Personally, I have never flown a Bonanza that was equipped with the
>tail cone antenna, but I have personally spoken to a pilot who has
>flown his that way in heavy IFR operations for over twenty years.
>Just how good do antennas really NEED to be?
>
>Mike also was a big exponent of using a set of VHF Navigation blades
>mounted as far back on the Bonanza fuselage as possible. The
>manufacturer of the antennas said they were way too close to the
>tail feathers to work properly. I have personally mounted several
>blade antennas in that position and they have all worked very well.
>
>Just some data for further thought.
And good data it is.
Folks often get their airplane antenna issues stirred into
a stew of some good and not-so-good data about "antenna
struggles". The majority of data in the wild comes from
folks wanting to watch tv from a station 60 miles away,
a ham operator who wishes to extract .5 microvolt signals
from a universe of noise, and the two way radio company
attempting to satisfy a fleet customer with 100 vehicles
that wander afar from home base.
All of these situations might gain a measure of improvement
by fine tuning swr, radiation patterns, coax losses,
installation losses, etc.
THEN you have airplanes. Airplanes almost never offer
opportunities to install the best antennas we know how
to do for reasons unique to airplanes. Weird shapes,
not enough acreage, aerodynamic buffeting, aerodynamic
drag, and general ugliness on an otherwise "fast" looking
airplane.
The really cool thing about airplane antennas is that
a wet string hung out the window would probably
suffice for 90% of the aviator's communications needs.
We got into a discussion on the List many years ago
about the relative utility of the new line of miniature
transceivers with puny transmitters . . . 1 to 2 watts.
There was a lot of concern for overall communications
performance. However, most worries were grounded in
memories of having witnessed John Wayne's harrowing
experiences exacerbated by too week a radio signal while
wrestling with 5 bad guys and a string of simultaneous
systems failures.
The environmental influences on aviation signal
strength are (1) line of sight limitations due to curvature
of the earth, (2) path loss (attenuation as a function
of distance and frequency) and (3) environmental
noise at the receive end. It turns out that a couple of
1 watt transceivers talking to each other on rudimentary
antennas had a range on the order of 1000 miles in free space.
As a practical matter, we rarely need to talk with
a facility that is more than 50 miles away. For an
airplane at 2000 AGL talking to a facility with 40'
high antennas, line-of-sight distance is 70+
miles. Bottom line: the NEED for high power
and finely tuned performance in antennas/feedlines
for the way we use radios in our airplanes is
exceedingly rare.
This discussion about SWR, etc is certainly
valuable for understanding the simple-ideas that
drive system performance. At the same time, I hope
that Bob doesn't spend a great deal of time seeking
the holy grail of 1:1 SWR, perfectly circular radiation
patterns and zero loss coax.
Nearly a century of practical experience has demonstrated
that (1) the grail is not attainable and (2) wouldn't
make an observable difference if it were attained.
Bob . . .
Message 5
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| Subject: | Comm Antenna & SWR: More Information |
At 11:05 PM 1/26/2011, you wrote:
>One more antenna that is not done right and still works fine. The
>ELT on many RV's is horizontal and inside the tail cone fairing. Or
>in the baggage area with only the top few inches not close to
>metal. Neither of these install techniques have good ground planes
>nor the correct orientation but they work with both the 121.5 and
>the 406 versions of ELT
Excellent point. This feeds directly into the assertions
I made in the post a few minutes ago. The satellite flying
overhead has no line-of-sight limitations nor is it plagued
with line noise, ignition noise and strong local radio
stations. It's as close as you can get to the ideal
receiving environment.
This is a large component of the recipe for success
in spite of poorly crafted or even crash-damaged
beacon antennas.
Bob . . .
Message 6
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At 11:29 PM 1/26/2011, you wrote:
>Bob,
>I'm sure you're familiar with this, but this blog is the first I've
>heard of it.
>More info is on the CAFE Blog at
><http://blog.cafefoundation.org/?p=2439>http://blog.cafefoundation.org/?p=2439.
>Stan Sutterfield
>
>
Cool! Thanks for the heads-up.
Bob . . .
Message 7
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| Subject: | coax antenna cable length |
That's the first I've heard of anything like this. As Bob has said, the
longer the feed cable (coax) the closer the match to the radio will be to 50
Ohms but you will then also have to contend with line losses.
The question than has to be what to do with the access cable? If you coil
it up you can be opening a whole new can or worms. Re-routing it can also
cause problems. Best to decide on the best possible routing and install
leaving just enough cable for drip loops.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Mike
Welch
Sent: January 26, 2011 11:02 PM
Subject: AeroElectric-List: coax antenna cable length
Guys,
I have seen it suggested that when cutting off an antenna cable
for your com radio, nav radio, etc., that you are supposed to cut
the cable at EVEN multiples of one length of a dipole mast.
In the example of a com radio, one article states the dipole length
of a com radio to be 20". Therefore, you should double this, and
use this new length to calculate your final minimum cable length.
Like this; dipole = 20", so our increment would be 40". Now,
beginning at the back of the radio (not at a junction of a pigtail),
start counting off 40" increments until we have enough cable to
comfortably reach the actual antenna. Meaning; only cut the cable at
40", 80", 120", 160", 200", etc.
If, after we've done an excellent routing of the cable, we find our
antenna is not located at a 40" increment, then we should proceed
to the next full length of our 40" increment prior to cutting the cable.
Here's my question; I read from a prominent, nationally known,
avionics guru that this is not all that necessary. If I recall correctly,
he said he has done SWR tests, and the cable length (cut off at even
multiples) had little effect on the antennas performance. In other
words, it didn't really matter what the cable length was, i.e.., 180"
or 205", etc.
If I'm a little fuzzy on my facts here, it's because this information
is from several years ago. But, after all these years, I really would
like to now the facts!!
Is it really all that critical what the cut-off measurement is for a coax
cable for aircraft radios?
Thanks, Mike Welch
Message 8
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| Subject: | Comm Antenna & SWR: More Information |
Hi Bob,
Don Panier at www.deltapopaviation.cpm makes and sells com, nav, adsb aprs
and transponder antennas that take their connection to the ground plane from
the mounting screws. The antenna does not have any metal contact on the
base other than the mounting screws. These work well in composite and metal
ac.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, January 27, 2011 7:19 AM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
<nuckolls.bob@aeroelectric.com>
At 11:05 PM 1/26/2011, you wrote:
>One more antenna that is not done right and still works fine. The
>ELT on many RV's is horizontal and inside the tail cone fairing. Or
>in the baggage area with only the top few inches not close to
>metal. Neither of these install techniques have good ground planes
>nor the correct orientation but they work with both the 121.5 and
>the 406 versions of ELT
Excellent point. This feeds directly into the assertions
I made in the post a few minutes ago. The satellite flying
overhead has no line-of-sight limitations nor is it plagued
with line noise, ignition noise and strong local radio
stations. It's as close as you can get to the ideal
receiving environment.
This is a large component of the recipe for success
in spite of poorly crafted or even crash-damaged
beacon antennas.
Bob . . .
Message 9
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| Subject: | Comm Antenna & SWR: More Information |
Make that www.deltapopaviation.com
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Don
Sent: Thursday, January 27, 2011 3:46 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
Hi Bob,
Don Panier deltapopaviation.makes and sells com, nav, adsb aprs
and transponder antennas that take their connection to the ground plane from
the mounting screws. The antenna does not have any metal contact on the
base other than the mounting screws. These work well in composite and metal
ac.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, January 27, 2011 7:19 AM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
<nuckolls.bob@aeroelectric.com>
At 11:05 PM 1/26/2011, you wrote:
>One more antenna that is not done right and still works fine. The
>ELT on many RV's is horizontal and inside the tail cone fairing. Or
>in the baggage area with only the top few inches not close to
>metal. Neither of these install techniques have good ground planes
>nor the correct orientation but they work with both the 121.5 and
>the 406 versions of ELT
Excellent point. This feeds directly into the assertions
I made in the post a few minutes ago. The satellite flying
overhead has no line-of-sight limitations nor is it plagued
with line noise, ignition noise and strong local radio
stations. It's as close as you can get to the ideal
receiving environment.
This is a large component of the recipe for success
in spite of poorly crafted or even crash-damaged
beacon antennas.
Bob . . .
Message 10
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| Subject: | Comm Antenna & SWR: Grounding the Ground Plane: |
Ref: Bob N's. Message 27 Posted on 1-25-11
With your antenna and the BNC connector in place there should be a dead
short from the ground plane to the braid of your coax. Mind you the other
end of the coax should be grounded to the case of the radio.
Noel
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bob
Falstad
Sent: January 26, 2011 11:27 PM
Subject: AeroElectric-List: Comm Antenna & SWR: Grounding the Ground Plane:
Ref: Bob N's. Message 27 Posted on 1-25-11
Bob N., et al,
Based on his reading of Figure 3-4 on page 28 of AC43.13-2B, my Ham/EE/PE
buddy asked me to check the resistance between the ground plane and the
ground system in my plane. (And yes, as you correctly surmised, I'm using a
B&C "forest of tabs" on the firewall for my grounding system supplemented
with your 37-pin Dsub ground bus for avionics grounds mounted next to it.)
As expected, there was a complete open between my ground plane and the
grounding system in the airplane. This is consistent with your comments in
the message referenced above.
But when, for example, a comm antenna is mounted on top of the wing on a
Cessna, I presume it is electrically bonded to the wing which acts as the
ground plane. But isn't the wing also part of the ground system for the
airplane itself? With a coax connector attached to the antenna isn't there
now two ground paths from the antenna to the radio chassis in its mounting
rack? Does this create a ground loop and if so, are its effects positive,
benign, or negative? Or is the ground through the coax between the antenna
and the radio isolated in the radio chassis so the loop isn't completed? In
thinking about my setup (if I had an-all metal airplane), it seems like the
loop would be completed since the BNC connector at the radio end of the feed
line connects to another BNC connector that is mounted in the back plane of
the radio (Garmin 430W) chassis and it appears to me that the pass-through
BNC connector in the chassis back plane isn't insulated from the radio
chassis itself.
Your thought and comments?
Best regards,
Bob Falstad
GlaStar N248BF
Message 11
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| Subject: | Comm Antenna & SWR: More Information |
The only ground plane I know of which is close to infinite is salt water.
Fibre glass boats commonly use the ocean itself as a ground plane for
radio... Believe me they can have problems too.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: January 26, 2011 10:44 PM
Subject: Re: AeroElectric-List: Comm Antenna & SWR: More Information
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier post, it is
actually 24" x 34", not 24" x 36" -- I had cut 2" off the length so that it
would fit in the space I had available). I also didn't mention that I cut
two slots in the ground plane so that it would fit over a couple of supports
for the floors in my baggage compartment. These slots are ~3" x 1/2" and
are about 10" aft of the antenna base and about 4" either side of the
fuselage centerline. Will these slots in the ground plane degrade the
ground plane's performance?
Not much . . . if any. Let's consider the way
a ground plane works. In an earlier post I
explained how the sum total of 4 'prefect'
radials routed 80% plus of energy delivered
to the end of the coax to be delivered to
the antenna.
Now, if you draw say 100 equally spaced lines
from the antenna location on your ground plane
out to the edge, we can see that the minimum 'radial'
length is on the order of 12". No single 12" radial
is very useful . . . but there's a lot of them.
The longest radial goes out to 2 or more corners.
They might be as short as 20' but perhaps longer
if the antenna is not directly centered on the sheet.
[]
Obviously, the ground plane is not "ideal". But
then lots of satisfactory antenna installations
were 'grounded' to small plates welded to the
structure of a rag-n-tube airplane. Terrible
radials.
Your ground plane sheet is blessed with a few
pretty good radials and lots of not so good
but the SUM TOTAL of their effects at the base
of the antenna is substantial . . . and probably
quite adequate.
With respect to 'measuring' resistance between
the antenna base and the airframe, know that
very few installations get such treatment.
Practiced installers know that certain processes
ALWAYS yield good bonding. Further, those same
processes yield joints with good longevity in
service.
If your coax is good, the connectors are properly
installed AND you apply reliable processes for
getting high pressure connection between antenna
base and ground plane, an micro-ohmmeter test will
be quite predictable and therefore redundant.
Antenna choice, revisit?
Cobham/Comant isn't very positive about bent whip antennas for Comm 1. They
say "Bent whips may not provide the best VSWR because of proximity to the
ground plane (aircraft skin), which can cause reflections, plus they lack
overall height. Remember, VHF antennas "like" to be tall and straight for
best operation." See FAQ #2.
Not true. It's the current flowing in about the bottom
20% of the antenna element that controls most of
an antenna's performance. In fact, it's common practice
to mechanically shorten an antenna with "capacity
hats" that act strongly in low current, high voltage
portion of the antenna element.
Bending the top of the antenna horizontal has little
effect on radiation pattern but will lower the frequency
of resonance.
Other than the antenna selection issue itself, this reading leads me to
three additional areas to investigate: ground plane symmetry, ground plane
size, and antenna mounting location on ground plane.
Go for the bonding . . . get that right and you're
98% done.
Re ground plane symmetry...
AC43.13-2B, paragraph 310(b) on page 27 says that "...ground plane symmetry
is critical." There is no reason or engineering data given but its a fairly
direct statement. After re-running the tests with my 24" x 34" practice
ground plane, I may cut it back to 24" x 24" to see what VSWR readings I get
with that size.
Please don't do this. AC43-13 was NOT crafted by
skilled practitioners of the arts or science of
building airplanes . . . That's another story.
See page 2 of
http://www.aeroelectric.com/articles/Getting_Started.pdf
Re ground plane size...
I understand that, in theory, the ideal ground plane is of infinite
dimension.
That's the 'perfect'. . . the 'ideal' is more practical
(For an aside, see quote below.) Bob N. says the practical ideal is a disc
with a radius equal to one-quarter of the wavelength. An on-line calculator
told me that the wavelength at 122.95 MHz is 8'. One fourth of that is 2'.
But that means the idealized disc should have a diameter of 4'. My ground
plane is only 24" wide -- half of what it should be. It isn't feasible to
put a ground plane 4' wide in my plane -- most of it would have to curl up
the sides of the fuselage which would defeat the purpose anyhow. Moreover,
AC43.13-2B, paragraph 310(b), page 27, says most antennas require a ground
plane size of approximately 24" x 24".
Which supports the assertions I made earlier about
AC43-13 . . . 24 x 24 is a practical 'ideal' ground
plane for 174 Mhz given that the 4 best radials are
only 17" long.
Re antenna mounting location on ground plane...
In addition to the issue of the symmetry of the ground plane itself, will it
make a difference in VSWR if the antenna base is not mounted in the center
of the ground plane. As I mentioned in my earlier post, I mounted the base
about 1/3 of the distance along the long axis so that the entire bent whip
would be "covered" by the ground plane. But if, electrically, the bent whip
really behaves like the straight piece of 12 AWG wire Bob N. used in his
experiment, then that seems to indicate that the antenna base needs to be
installed in the center of the ground plane, whether the ground plane is
square or rectangular.
Next steps...
I'm finishing up the final terminations on my feed lines and will jury-rig
an external ground plane in order to re-do the tests outside the airplane as
Bob N. suggested. I hope to have the new test data to you in the next
couple of days.
A good experiment . . . if you're really curious and
want to do it.
Bob . . .
Message 12
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| Subject: | Comm Antenna & SWR: More Information |
Again you have to ask is the signal going full force in the direction you
want? It makes no sense to set up a properly tuned antenna in what is
essentially a faraday cage.
An ELT wants to be seen. That means an omni-directional output. With the
antenna in the tailcone you may not be seen at an airport two miles directly
behind your plane. You chances of being seen by a station in front of you
are even less.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Don
Sent: January 27, 2011 12:36 AM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
One more antenna that is not done right and still works fine. The ELT on
many RV's is horizontal and inside the tail cone fairing. Or in the baggage
area with only the top few inches not close to metal. Neither of these
install techniques have good ground planes nor the correct orientation but
they work with both the 121.5 and the 406 versions of ELT
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
BobsV35B@aol.com
Sent: Wednesday, January 26, 2011 7:44 PM
Subject: Re: AeroElectric-List: Comm Antenna & SWR: More Information
Good Evening All,
This discussion about ground planes has forced me to send another one of my
way off subject messages! <G>
Some of you may be aware of the speed modifications that Mike Smith was
selling for Bonanzas a few years ago. While Bonanzas are certainly NOT
homebuilt aircraft, Mike's work was very much in the realm of what
homebuilders do. He guaranteed a speed increase of at least ten knots on any
Bonanza that used his full set of speed kits.
In his quest for speed, he took EVERYTHING off the top of the fuselage and
as much off the belly as humanly possible. He even installed a VHF
communication antenna in a fiberglass tail cone. It was horizontally
oriented rather than vertical and the ground plane was no more than six
inches by eight inches.
Did it work? Some folks found that it was a perfectly usable solution and
are still using it regularly. Others have either eliminated it or added
another stock antenna on the belly.
Personally, I have never flown a Bonanza that was equipped with the tail
cone antenna, but I have personally spoken to a pilot who has flown his that
way in heavy IFR operations for over twenty years. Just how good do antennas
really NEED to be?
Mike also was a big exponent of using a set of VHF Navigation blades mounted
as far back on the Bonanza fuselage as possible. The manufacturer of the
antennas said they were way too close to the tail feathers to work properly.
I have personally mounted several blade antennas in that position and they
have all worked very well.
Just some data for further thought.
Happy Skies,
Old Bob
Downers Grove, IL
LL22
Stearman 3977A
Do Not Archive
In a message dated 1/26/2011 9:19:32 P.M. Central Standard Time,
nuckolls.bob@aeroelectric.com writes:
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier post, it is
actually 24" x 34", not 24" x 36" -- I had cut 2" off the length so that it
would fit in the space I had available). I also didn't mention that I cut
two slots in the ground plane so that it would fit over a couple of supports
for the floors in my baggage compartment. These slots are ~3" x 1/2" and
are about 10" aft of the antenna base and about 4" either side of the
fuselage centerline. Will these slots in the ground plane degrade the
ground plane's performance?
http://www.matronics.com/Navigator?AeroElectric-List
http://forums.matronics.com
http://www.matronics.com/contribution
Message 13
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| Subject: | Comm Antenna & SWR: More Information |
The important thing with com antennas is good omnidirectional ( all
directions ) coverage. A horizontally polarized antenna in a tailcone,
outside of having too small a ground plane, will have a dead area in front
of the plane and another one behind it. I can't see how this can be
considered good for airplanes heading into or away from a control zone.
Many large aircraft actually have antennae above and below the fuselage to
allow communication with other aircraft as well as ground.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
BobsV35B@aol.com
Sent: January 27, 2011 12:14 AM
Subject: Re: AeroElectric-List: Comm Antenna & SWR: More Information
Good Evening All,
This discussion about ground planes has forced me to send another one of my
way off subject messages! <G>
Some of you may be aware of the speed modifications that Mike Smith was
selling for Bonanzas a few years ago. While Bonanzas are certainly NOT
homebuilt aircraft, Mike's work was very much in the realm of what
homebuilders do. He guaranteed a speed increase of at least ten knots on any
Bonanza that used his full set of speed kits.
In his quest for speed, he took EVERYTHING off the top of the fuselage and
as much off the belly as humanly possible. He even installed a VHF
communication antenna in a fiberglass tail cone. It was horizontally
oriented rather than vertical and the ground plane was no more than six
inches by eight inches.
Did it work? Some folks found that it was a perfectly usable solution and
are still using it regularly. Others have either eliminated it or added
another stock antenna on the belly.
Personally, I have never flown a Bonanza that was equipped with the tail
cone antenna, but I have personally spoken to a pilot who has flown his that
way in heavy IFR operations for over twenty years. Just how good do antennas
really NEED to be?
Mike also was a big exponent of using a set of VHF Navigation blades mounted
as far back on the Bonanza fuselage as possible. The manufacturer of the
antennas said they were way too close to the tail feathers to work properly.
I have personally mounted several blade antennas in that position and they
have all worked very well.
Just some data for further thought.
Happy Skies,
Old Bob
Downers Grove, IL
LL22
Stearman 3977A
Do Not Archive
In a message dated 1/26/2011 9:19:32 P.M. Central Standard Time,
nuckolls.bob@aeroelectric.com writes:
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier post, it is
actually 24" x 34", not 24" x 36" -- I had cut 2" off the length so that it
would fit in the space I had available). I also didn't mention that I cut
two slots in the ground plane so that it would fit over a couple of supports
for the floors in my baggage compartment. These slots are ~3" x 1/2" and
are about 10" aft of the antenna base and about 4" either side of the
fuselage centerline. Will these slots in the ground plane degrade the
ground plane's performance?
Message 14
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I think there is a typo there... I believe they mean to say,
=9CEven helium the smallest gas atom, cannot pass through
it=9D.
Also isn=99t hydrogen smaller than helium? One electron is
smaller than two on the atomic level. However on a molecular level
it=99s true. Helium being inert is He. Hydrogen being so active
is H2 a lot larger.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Speedy11@aol.com
Sent: January 27, 2011 12:59 AM
Subject: AeroElectric-List: Graphene
Bob,
I'm sure you're familiar with this, but this blog is the first I've
heard of it.
More info is on the CAFE Blog at
http://blog.cafefoundation.org/?p=2439.
Stan Sutterfield
Thin, Light, Strong, and Energy Dense
by Dean Sigler on 01/07/2011
<http://nobelprize.org/nobel_prizes/physics/laureates/2010/press.html>
2010=99s Nobel Prize in Physics went to Andre Geim and Konstantin
Novoselov, who extracted graphene from a piece of graphite when they
stuck a piece of adhesive tape to it and peeled away a single atom-thick
layer of the thinnest, strongest material in the world.
The Nobel Prize web site explains other remarkable properties of this
new material. =9CAs a conductor of electricity it performs as
well as copper. As a conductor of heat it outperforms all other known
materials. It is almost completely transparent, yet so dense that not
even helium, the smallest gas atom, can pass through it. Carbon, the
basis of all known life on earth, has surprised us once again.=9D
When mixed into plastics, graphene can turn them into conductors of
electricity while making them more heat resistant and mechanically
robust.
Over 28,000 square feet per gram for a single layer of the material
=93 or about the size of a football field
Message 15
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| Subject: | Re: Comm Antenna & SWR: More Information |
Good Evening Noel,
I don't think anyone will disagree with what you say, but the point is tha
t
a lot of good competent and concientuous folks have found that the crummy
location does work acceptably. You and I can agree it is not good, but if
it works for others, are we supposed to tell them it is not allowed?
As 'Lectric Bob has said, chances are a wet noodle will work most of the
time.
While I know folks who are still using the stick in the tail cone, I know
more who have given up on it and gone to a more conventional antenna.
As Always.It All Depends! <G>
Do Not Archive
Happy Skies,
Old Bob
In a message dated 1/27/2011 6:27:12 P.M. Central Standard Time,
noelloveys@yahoo.ca writes:
The important thing with com antennas is good omnidirectional ( all
directions ) coverage. A horizontally polarized antenna in a tailcone,
outside
of having too small a ground plane, will have a dead area in front of the
plane and another one behind it. I can=99t see how this can be con
sidered good
for airplanes heading into or away from a control zone.
Many large aircraft actually have antennae above and below the fuselage
to
allow communication with other aircraft as well as ground.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of BobsV3
5B@aol.com
Sent: January 27, 2011 12:14 AM
Subject: Re: AeroElectric-List: Comm Antenna & SWR: More Information
Good Evening All,
This discussion about ground planes has forced me to send another one of
my way off subject messages! <G>
Some of you may be aware of the speed modifications that Mike Smith was
selling for Bonanzas a few years ago. While Bonanzas are certainly NOT
homebuilt aircraft, Mike's work was very much in the realm of what homebu
ilders
do. He guaranteed a speed increase of at least ten knots on any Bonanza
that
used his full set of speed kits.
In his quest for speed, he took EVERYTHING off the top of the fuselage an
d
as much off the belly as humanly possible. He even installed a VHF
communication antenna in a fiberglass tail cone. It was horizontally orie
nted
rather than vertical and the ground plane was no more than six inches by
eight
inches.
Did it work? Some folks found that it was a perfectly usable solution and
are still using it regularly. Others have either eliminated it or added
another stock antenna on the belly.
Personally, I have never flown a Bonanza that was equipped with the tail
cone antenna, but I have personally spoken to a pilot who has flown his
that
way in heavy IFR operations for over twenty years. Just how good do
antennas really NEED to be?
Mike also was a big exponent of using a set of VHF Navigation blades
mounted as far back on the Bonanza fuselage as possible. The manufacturer
of the
antennas said they were way too close to the tail feathers to work
properly. I have personally mounted several blade antennas in that positi
on and
they have all worked very well.
Just some data for further thought.
Happy Skies,
Old Bob
Downers Grove, IL
LL22
Stearman 3977A
Do Not Archive
In a message dated 1/26/2011 9:19:32 P.M. Central Standard Time,
nuckolls.bob@aeroelectric.com writes:
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier post, it
is
actually 24" x 34", not 24" x 36" -- I had cut 2" off the length so that
it would fit in the space I had available). I also didn't mention that
I
cut two slots in the ground plane so that it would fit over a couple of
supports for the floors in my baggage compartment. These slots are ~3"
x 1/2"
and are about 10" aft of the antenna base and about 4" either side of the
fuselage centerline. Will these slots in the ground plane degrade the gr
ound
plane's performance?
http://www.matronics.com/Navigator?AeroElectric-List
http://forums.matronics.com
http://www.matronics.com/contribution
========================
============
(http://www.matronics.com/Navigator?AeroElectric-List)
========================
============
========================
============
(http://www.matronics.com/contribution)
========================
============
Message 16
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| Subject: | coax antenna cable length |
At 06:27 PM 1/27/2011, you wrote:
>That's the first I've heard of anything like this. As Bob has said,
>the longer the feed cable (coax) the closer the match to the radio
>will be to 50 Ohms but you will then also have to contend with line losses.
>
>The question than has to be what to do with the access cable? If
>you coil it up you can be opening a whole new can or
>worms. Re-routing it can also cause problems. Best to decide on
>the best possible routing and install leaving just enough cable for drip loops.
I did not intended proffer the idea that one
would purposely ADD coax to a feedline for
the purpose of reducing SWR. It is because
longer feedlines ADD losses that the SWR
appears to improve while in fact, the
effects of real SWR are being masked by
those losses. It was an observation of
fact, not a recommendation.
Bob . . .
Message 17
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| Subject: | Comm Antenna & SWR: More Information |
> The antenna does not have any metal contact on the
>base other than the mounting screws. These work well in composite and metal
>ac.
Virtually ALL comm antennas make ground plane
connections only through their mounting screws.
I've seen installation manuals suggest that the
skin of the airplane under the base of an antenna
be cleaned to the bare metal . . . ostensibly for
the purpose of improving on the antenna to airplane
bonding.
Bonding is achieved by HIGH PRESSURE joints in
metallic fasteners. I crafted this drawing about
5 years ago. . .
http://aeroelectric.com/Pictures/Antenna/Comm_Antenna_Installation.gif
I DID suggest that the stock gasket shipped with
many antennas be discarded and that the base be
moisture sealed to the skin with a bead of RTV.
However, you'll not an emphasis on clean metal
circles around each of the mounting fasteners
where we'll exploit the pressure that cranking
down on the nut will offer.
Stray outside the clamp-up radius around each
bolt very far, and any notion of long term, high
quality boding between the parts becomes a fantasy.
Bob . . .
Message 18
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| Subject: | Comm Antenna & SWR: More Information |
At 07:12 PM 1/27/2011, you wrote:
>The important thing with com antennas is good omnidirectional ( all
>directions ) coverage.
"Good" is non-quantified. I've seen horizontal pattern
plots for comm antennas that had large (10db or more)
variations around the compass . . . but these antennas
proved adequate to the performance necessary.
>A horizontally polarized antenna in a tailcone, outside of having
>too small a ground plane, will have a dead area in front of the
>plane and another one behind it.
???? The VOR antenna whiskers are horizontally polarized
dipole with major lobes fore and aft with nulls off to the
sides. Further, dipole antennas require no ground plane.
> I can't see how this can be considered good for airplanes heading
> into or away from a control zone.
No such "null" exists fore and aft.
>
>Many large aircraft actually have antennae above and below the
>fuselage to allow communication with other aircraft as well as ground.
???? Antenna placement is largely a matter of separation
between the antennas for similar systems . . . and judicious
use of real estate. Once an airplane is airborne, relative
differences between top and bottom mounted antennas is
insignificant.
Bob . . .
Message 19
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| Subject: | Comm Antenna & SWR: More Information |
Thanks Bob. I was led to believe that the antenna and skin needed tp be
paint free and making good contact. This is what the instructions that came
with my commant and Avidyne Ryan antennas had to say. Glad that I mow
understand the actual requirements.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Thursday, January 27, 2011 5:41 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
<nuckolls.bob@aeroelectric.com>
> The antenna does not have any metal contact on the
>base other than the mounting screws. These work well in composite and metal
>ac.
Virtually ALL comm antennas make ground plane
connections only through their mounting screws.
I've seen installation manuals suggest that the
skin of the airplane under the base of an antenna
be cleaned to the bare metal . . . ostensibly for
the purpose of improving on the antenna to airplane
bonding.
Bonding is achieved by HIGH PRESSURE joints in
metallic fasteners. I crafted this drawing about
5 years ago. . .
http://aeroelectric.com/Pictures/Antenna/Comm_Antenna_Installation.gif
I DID suggest that the stock gasket shipped with
many antennas be discarded and that the base be
moisture sealed to the skin with a bead of RTV.
However, you'll not an emphasis on clean metal
circles around each of the mounting fasteners
where we'll exploit the pressure that cranking
down on the nut will offer.
Stray outside the clamp-up radius around each
bolt very far, and any notion of long term, high
quality boding between the parts becomes a fantasy.
Bob . . .
Message 20
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| Subject: | Comm Antenna & SWR: More Information |
ELT's are designed to be seen by satellites. Until
the present 405 Mhz with superior locating capability
came along the
I recall hearing a report about 20 years ago that
for EVERY downed airplane located, ELT was a factor
in a very small percentage of those finds . . . about
6% if I recall correctly. Don't know how much better
the stats are now.
In any case installation of ELT antennas is a
"gee I hope this works when and if they
need it" kind of design task. There is no
place on an airplane that is immune from
crash-induced damage. Equipment placement
is based on the study of crash history.
So when on short final to the rocks, one
should endeavor to crash like most other
folks crashed such that their ELT survived.
Shadowing to the extent that some ground
based facility two miles away doesn't hear
it is the very least of concerns.
>
>One more antenna that is not done right and still works fine. The
>ELT on many RV's is horizontal and inside the tail cone fairing. Or
>in the baggage area with only the top few inches not close to
>metal. Neither of these install techniques have good ground planes
>nor the correct orientation but they work with both the 121.5 and
>the 406 versions of ELT
On what basis were these installations said
to "work fine". Have these installations
been reviewed by the ELT manufacturer? I
can't imagine anyone signing off on an
installation that didn't provide the customary
ground plane combined with a good view of the
sky assuming the wreckage was still upright.
Emacs!
Here's the ELT antennas on a Beechjet. Both
are installed under a fiberglas fairing just
forward of the vertical fin.
Emacs!
The 121.5 antenna had to be folded over under the
fiberglas to clear some ductwork. This distortion
caused the ELT to go into "hi SWR shutdown".
Emacs!
I made the suggestion that we build a top-hat
loaded vertical that could be tuned for that
location and wouldn't have to be bent over under
the fairing.
Certification time-line issues shot that idea down.
They just widened the window on the SWR monitor
to prevent the shutdown. But even with this band-aid
approach, close attention was paid to adequate
radiation performance and patterns.
If one hopes to achieve better than 6% probability
of the ELT being useful, one should be wary
of pronouncements of "works fine" when deviating
from TSO approved manufacturer's recommendations.
Horizontal polarization isn't a big thing but not
having a ground plane and clearest possible view
of the sky is problematic.
Bob . . .
>
>From: owner-aeroelectric-list-server@matronics.com
>[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
>BobsV35B@aol.com
>Sent: Wednesday, January 26, 2011 7:44 PM
>To: aeroelectric-list@matronics.com
>Subject: Re: AeroElectric-List: Comm Antenna & SWR: More Information
>
>Good Evening All,
>
>This discussion about ground planes has forced me to send another
>one of my way off subject messages! <G>
>
>Some of you may be aware of the speed modifications that Mike Smith
>was selling for Bonanzas a few years ago. While Bonanzas are
>certainly NOT homebuilt aircraft, Mike's work was very much in the
>realm of what homebuilders do. He guaranteed a speed increase of at
>least ten knots on any Bonanza that used his full set of speed kits.
>
>In his quest for speed, he took EVERYTHING off the top of the
>fuselage and as much off the belly as humanly possible. He even
>installed a VHF communication antenna in a fiberglass tail cone. It
>was horizontally oriented rather than vertical and the ground plane
>was no more than six inches by eight inches.
>
>Did it work? Some folks found that it was a perfectly usable
>solution and are still using it regularly. Others have either
>eliminated it or added another stock antenna on the belly.
>
>Personally, I have never flown a Bonanza that was equipped with the
>tail cone antenna, but I have personally spoken to a pilot who has
>flown his that way in heavy IFR operations for over twenty years.
>Just how good do antennas really NEED to be?
>
>Mike also was a big exponent of using a set of VHF Navigation blades
>mounted as far back on the Bonanza fuselage as possible. The
>manufacturer of the antennas said they were way too close to the
>tail feathers to work properly. I have personally mounted several
>blade antennas in that position and they have all worked very well.
>
>Just some data for further thought.
>
>Happy Skies,
>
>Old Bob
>Downers Grove, IL
>LL22
>Stearman 3977A
>
>Do Not Archive
>
>In a message dated 1/26/2011 9:19:32 P.M. Central Standard Time,
>nuckolls.bob@aeroelectric.com writes:
>
>Additional detail about my ground plane installation.
>
>My ground plane isn't symmetrical (and, contrary to my earlier post,
>it is actually 24" x 34", not 24" x 36" -- I had cut 2" off the
>length so that it would fit in the space I had available). I also
>didn't mention that I cut two slots in the ground plane so that it
>would fit over a couple of supports for the floors in my baggage
>compartment. These slots are ~3" x 1/2" and are about 10" aft of
>the antenna base and about 4" either side of the fuselage
>centerline. Will these slots in the ground plane degrade the ground
>plane's performance?
>
>
>http://www.matronics.com/Navigator?AeroElectric-List
>
>
>http://forums.matronics.com
>
>
>http://www.matronics.com/contribution
>
>
>http://www.matronics.com/Navigator?AeroElectric-List
>
>
>http://forums.matronics.com
>
>
>http://www.matronics.com/contribution
>
>
><http://www.matronics.com/Navigator?AeroElectric-List>http://www.matronics.com/Navigator?AeroElectric-List
><http://www.matronics.com/contribution>http://www.matronics.com/contribution
>
>
>No virus found in this message.
>Checked by AVG - <http://www.avg.com>www.avg.com
Bob . . .
Message 21
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| Subject: | Comm Antenna & SWR: More Information |
At 10:36 PM 1/27/2011, you wrote:
>
>Thanks Bob. I was led to believe that the antenna and skin needed tp be
>paint free and making good contact. This is what the instructions that came
>with my commant and Avidyne Ryan antennas had to say. Glad that I mow
>understand the actual requirements.
It's not uncommon for folks who specialize in
one technology to be weak in peripheral technologies.
Anyone who has worked in the EMC lab to identify and
control the transfer of RF energy understands that
large area, low pressure, open-to-atmosphere interfaces
between two metallic surfaces is NOT a bond of any useful
kind. Gas tight over lifetime of the airplane is
the goal.
If one could "tack weld" the base of an antenna
to the skin of the airplane in a half-dozen places
around the edge, the RF bonding guys would be
delighted. The next best thing is to make sure the
conduction footprints around the mounting bolts
pretend like they're welded to the airplane
Bob . . .
Message 22
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| Subject: | Comm Antenna & SWR: More Questions... |
Bob and all,
During an emergency landing too many aircraft go over on their backs. I
suspect that the back contact and sliding in too many instances scrapes
off or otherwise damages antenna like the ELT typically use.
>From that situation, I have wondered about a design concept that would
allow the ELT to feed either two or one antennas with enough radiation
to get someone's attention. The thought goes something like this. Have
an antenna both top and bottom of the fuselage region. Hoping that one
survives the impact and will radiate the ELT signal.
Any thoughts about a design that could "reasonably" match and feed
either two (if both survive) or the remaining antenna....
David
-------------------------------------------------------------------------
-------
----- Original Message -----
From: Robert L. Nuckolls, III
To: aeroelectric-list@matronics.com
Sent: Thursday, January 27, 2011 7:14 PM
Subject: RE: AeroElectric-List: Comm Antenna & SWR: More Information
ELT's are designed to be seen by satellites. Until
the present 405 Mhz with superior locating capability
came along the
I recall hearing a report about 20 years ago that
for EVERY downed airplane located, ELT was a factor
in a very small percentage of those finds . . . about
6% if I recall correctly. Don't know how much better
the stats are now.
In any case installation of ELT antennas is a
"gee I hope this works when and if they
need it" kind of design task. There is no
place on an airplane that is immune from
crash-induced damage. Equipment placement
is based on the study of crash history.
So when on short final to the rocks, one
should endeavor to crash like most other
folks crashed such that their ELT survived.
Shadowing to the extent that some ground
based facility two miles away doesn't hear
it is the very least of concerns.
One more antenna that is not done right and still works fine. The
ELT on many RV's is horizontal and inside the tail cone fairing. Or in
the baggage area with only the top few inches not close to metal.
Neither of these install techniques have good ground planes nor the
correct orientation but they work with both the 121.5 and the 406
versions of ELT
On what basis were these installations said
to "work fine". Have these installations
been reviewed by the ELT manufacturer? I
can't imagine anyone signing off on an
installation that didn't provide the customary
ground plane combined with a good view of the
sky assuming the wreckage was still upright.
Here's the ELT antennas on a Beechjet. Both
are installed under a fiberglas fairing just
forward of the vertical fin.
The 121.5 antenna had to be folded over under the
fiberglas to clear some ductwork. This distortion
caused the ELT to go into "hi SWR shutdown".
I made the suggestion that we build a top-hat
loaded vertical that could be tuned for that
location and wouldn't have to be bent over under
the fairing.
Certification time-line issues shot that idea down.
They just widened the window on the SWR monitor
to prevent the shutdown. But even with this band-aid
approach, close attention was paid to adequate
radiation performance and patterns.
If one hopes to achieve better than 6% probability
of the ELT being useful, one should be wary
of pronouncements of "works fine" when deviating
from TSO approved manufacturer's recommendations.
Horizontal polarization isn't a big thing but not
having a ground plane and clearest possible view
of the sky is problematic.
Bob . . .
From: owner-aeroelectric-list-server@matronics.com [
mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
BobsV35B@aol.com
Sent: Wednesday, January 26, 2011 7:44 PM
To: aeroelectric-list@matronics.com
Subject: Re: AeroElectric-List: Comm Antenna & SWR: More Information
Good Evening All,
This discussion about ground planes has forced me to send another
one of my way off subject messages! <G>
Some of you may be aware of the speed modifications that Mike Smith
was selling for Bonanzas a few years ago. While Bonanzas are certainly
NOT homebuilt aircraft, Mike's work was very much in the realm of what
homebuilders do. He guaranteed a speed increase of at least ten knots on
any Bonanza that used his full set of speed kits.
In his quest for speed, he took EVERYTHING off the top of the
fuselage and as much off the belly as humanly possible. He even
installed a VHF communication antenna in a fiberglass tail cone. It was
horizontally oriented rather than vertical and the ground plane was no
more than six inches by eight inches.
Did it work? Some folks found that it was a perfectly usable
solution and are still using it regularly. Others have either eliminated
it or added another stock antenna on the belly.
Personally, I have never flown a Bonanza that was equipped with the
tail cone antenna, but I have personally spoken to a pilot who has flown
his that way in heavy IFR operations for over twenty years. Just how
good do antennas really NEED to be?
Mike also was a big exponent of using a set of VHF Navigation blades
mounted as far back on the Bonanza fuselage as possible. The
manufacturer of the antennas said they were way too close to the tail
feathers to work properly. I have personally mounted several blade
antennas in that position and they have all worked very well.
Just some data for further thought.
Happy Skies,
Old Bob
Downers Grove, IL
LL22
Stearman 3977A
Do Not Archive
In a message dated 1/26/2011 9:19:32 P.M. Central Standard Time,
nuckolls.bob@aeroelectric.com writes:
Additional detail about my ground plane installation.
My ground plane isn't symmetrical (and, contrary to my earlier
post, it is actually 24" x 34", not 24" x 36" -- I had cut 2" off the
length so that it would fit in the space I had available). I also
didn't mention that I cut two slots in the ground plane so that it would
fit over a couple of supports for the floors in my baggage compartment.
These slots are ~3" x 1/2" and are about 10" aft of the antenna base and
about 4" either side of the fuselage centerline. Will these slots in
the ground plane degrade the ground plane's performance?
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01/27/11
Bob . . .
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