Today's Message Index:
----------------------
1. 01:31 AM - Re: Ground plane diameter (Bob Verwey)
2. 06:58 AM - Re: Ground plane diameter (Robert L. Nuckolls, III)
3. 08:13 AM - Re: Speakers for helmet installation (Eric M. Jones)
4. 08:13 AM - Re: Ground plane diameter (Bob Verwey)
5. 09:06 AM - Re: Ground plane diameter (Robert L. Nuckolls, III)
6. 09:07 AM - Re: Ground plane diameter (Christopher Cee Stone)
7. 09:37 AM - Re: Ground plane diameter (Fisher Paul A.)
8. 09:55 AM - Re: Ground plane diameter (Paul Thomson)
9. 10:01 AM - Re: Ground plane diameter (Christopher Cee Stone)
10. 10:36 AM - Re: Ground plane diameter (Robert L. Nuckolls, III)
11. 10:53 AM - Re: Re: Speakers for helmet installation (Richard Girard)
12. 10:57 AM - Re: Ground plane diameter (Robert L. Nuckolls, III)
13. 11:07 AM - Re: Ground plane diameter (Robert L. Nuckolls, III)
14. 11:49 AM - Re: Eye Beam Mini LED / RF interference (Eric M. Jones)
15. 12:24 PM - Re: Speakers for helmet installation (Peter Pengilly)
Message 1
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Subject: | Re: Ground plane diameter |
If we consider the simple whip antenna for our VHF comms, what is the best
trimmed length for the antenna part and the ground plane diameter to
optimise the frequencies in the early '120's?
Best...
Bob Verwey
On 26 February 2013 19:02, R. curtis <mrspudandcompany@verizon.net> wrote:
> mrspudandcompany@verizon.net>
>
>
>> At 10:27 PM 2/25/2013, you wrote:
>>
>>> OK, thanks Bob. It operates on 978 Mhz so I probably could have figured
>>> it out by breaking out my ARRL Antenna Book but I guess I was just a bit
>>> on the lazy side.
>>>
>>
>> Very good. Yes, 978 MHz does work out to
>> a 6" diameter ground plane . . .
>>
>
>
> I have seen often that antennas get cut off to tune
> for maximum radiation. Is the ground plane as
> critical in dimension as the radiating element?
>
> Roger
>
> --
>
> Do you have a slow PC? Try a Free scan http://www.spamfighter.com/**
> SLOW-PCfighter?cid=sigen<http://www.spamfighter.com/SLOW-PCfighter?cid=sigen>
>
>
Message 2
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Subject: | Re: Ground plane diameter |
At 03:29 AM 2/28/2013, you wrote:
>If we consider the simple whip antenna for our VHF comms, what is
>the best trimmed length for the antenna part and the ground plane
>diameter to optimise the frequencies in the early '120's?
Center of the VHF comm spectrum is (118+135)/2 or 127.5 MHz
Free space full wavelength in meters is 300/127.5 = 2.35M
2.35M x 39.34 in/meter yields 92"
1/4 wave radials (or antennas) at 127.5 are
92/4 or 23".
Bob . . .
Message 3
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Subject: | Re: Speakers for helmet installation |
> All, I fly a trike wearing a full face Shoei helmet. While the helmet doesn't
seal my ears like headphones ........... Can anyone recommend a particular speaker
or mic cartridge that has worked for you?
> Rick Girard
Dear Rick,
Not only is there technical skill on this website, but good advice too, I hope.
The problem you are having is called "Target Fixation". What you need to do is
sit down and imagine how to get where you want to be without adding unnecessary
restraints such as "finding a use for a Shoei helmet". Or in other words, use
the right tool for the job. There are helmets with built in headphones and full
face-shields too. No problem.
One powerfull tool I have used is to just sell one device on Ebay and buy what
you need there too.
Bada bing bada boom....
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=395274#395274
Message 4
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Subject: | Re: Ground plane diameter |
Thanks Bob,
Care to elaborate on the ground plane a little? If the structure of the
aircraft is 'Cub-like' steel tubing, and one mounts the antenna on the
roof, is it sufficient to use the airframe as the groundplane?
Bob Verwey
On 28 February 2013 16:53, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com**>
>
> At 03:29 AM 2/28/2013, you wrote:
>
>> If we consider the simple whip antenna for our VHF comms, what is the
>> best trimmed length for the antenna part and the ground plane diameter to
>> optimise the frequencies in the early '120's?
>>
>
> Center of the VHF comm spectrum is (118+135)/2 or 127.5 MHz
>
> Free space full wavelength in meters is 300/127.5 = 2.35M
>
> 2.35M x 39.34 in/meter yields 92"
>
> 1/4 wave radials (or antennas) at 127.5 are
> 92/4 or 23".
>
>
> Bob . . .
>
>
Message 5
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Subject: | Re: Ground plane diameter |
At 10:10 AM 2/28/2013, you wrote:
>Thanks Bob,
>
>Care to elaborate on the ground plane a little? If the structure of
>the aircraft is 'Cub-like' steel tubing, and one mounts the antenna
>on the roof, is it sufficient to use the airframe as the groundplane?
ANY conductive material can be brought into service
as a 'ground'. Given our unique line-of-sight, short-range
expectations for radio communications, a wet-string would
probably serve 96% of your communications expectations.
Consider the lowly hand-held. Talk about compromised
ground planes!! The rubber duck in a sweaty fist works
for some situations, other situations (mostly driven by
customer's willingness to pay) are optimized to the
best-we-know-how-to-do. Most of us will secure happiness with
some intermediate but decidedly less expensive configuration.
ANY combination you choose to try should be first tailored
for lowest possible SWR over the range of interest. The
transmitter has no idea what's at the other end of the
feedline. Gross efficiency and/or radiation patterns are
separate issues not easily measured and massaged.
Are there things we could do that are 'better' than
using a rag-covered-tube ground plane? Sure. Would the
guy at the other end of the link know the difference?
Probably not. This is but one of several advantages
we enjoy over the drivers of TC iron, we can try it.
If found insufficient to design goals, do something
different.
Bob . . .
Message 6
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Subject: | Re: Ground plane diameter |
Bob...
I follow your calcs and the underlying physics until I see the 300/127.5
2.35M. Where is the 300 from? What does it represent?
Always learning!
Chris Stone
On Thu, Feb 28, 2013 at 6:53 AM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> nuckolls.bob@aeroelectric.com**>
>
>
> At 03:29 AM 2/28/2013, you wrote:
>
>> If we consider the simple whip antenna for our VHF comms, what is the
>> best trimmed length for the antenna part and the ground plane diameter to
>> optimise the frequencies in the early '120's?
>>
>
> Center of the VHF comm spectrum is (118+135)/2 or 127.5 MHz
>
> Free space full wavelength in meters is 300/127.5 = 2.35M
>
> 2.35M x 39.34 in/meter yields 92"
>
> 1/4 wave radials (or antennas) at 127.5 are
> 92/4 or 23".
>
>
> Bob . . .
>
>
Message 7
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Subject: | Ground plane diameter |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Message 8
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Subject: | Re: Ground plane diameter |
Then would be the recommendation for a more modern design that is all carbo
n fiber?- The carbon is conductive, but absorbs radiation instead of refl
ecting it from what I understand.- Go with a foil circle or strips of the
appropriate diameter on the outside of the carbon, but under the paint?-
=0A=0AThanks=0A=0APaul=0A=0A=0A=0A=0A________________________________=0A F
rom: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>=0ATo: aeroel
ectric-list@matronics.com =0ASent: Thursday, February 28, 2013 11:05 AM=0AS
ubject: Re: AeroElectric-List: Ground plane diameter=0A =0A--> AeroElectric
-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectr
ic.com>=0A=0AAt 10:10 AM 2/28/2013, you wrote:=0A> Thanks Bob,=0A> =0A> Car
e to elaborate on the ground plane a little? If the structure of the aircra
ft is 'Cub-like' steel tubing, and one mounts the antenna on the roof, is i
t sufficient to use the airframe as the groundplane?=0A=0A- ANY conductiv
e material can be brought into service=0A- as a 'ground'. Given our uniqu
e line-of-sight, short-range=0A- expectations for radio communications, a
wet-string would=0A- probably serve 96% of your communications expectati
=============
Message 9
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Subject: | Re: Ground plane diameter |
Ahhh... Yes.
Still mired in English units 186,000 miles per second.
Thanks!
chris stone
On Thu, Feb 28, 2013 at 9:34 AM, Fisher Paul A.
<FisherPaulA@johndeere.com>wrote:
> I=99d like to try to answer this:****
>
> ** **
>
> 300 million meters per second is roughly the speed of light =93 als
o about
> the speed the radio waves propagate. Dividing this by the frequency in
> megahertz gives you the wave length. So 300,000,000/127,500,000 = 2.35
> meters. ****
>
> ** **
>
> ** **
>
> seems like this was on the test for my ham license surprising I
still
> remember it!****
>
> ** **
>
> Paul Fisher****
>
> ** **
>
> ** **
>
> *From:* owner-aeroelectric-list-server@matronics.com [mailto:
> owner-aeroelectric-list-server@matronics.com] *On Behalf Of *Christopher
> Cee Stone
> *Sent:* Thursday, February 28, 2013 11:07 AM
> *To:* aeroelectric-list@matronics.com
> *Subject:* Re: AeroElectric-List: Ground plane diameter****
>
> ** **
>
> Bob...****
>
> ** **
>
> I follow your calcs and the underlying physics until I see the 300/127.5
> 2.35M. Where is the 300 from? What does it represent?****
>
> ** **
>
> Always learning!****
>
> ** **
>
> Chris Stone****
>
> ** **
>
Message 10
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Subject: | Re: Ground plane diameter |
At 11:48 AM 2/28/2013, you wrote:
>Then would be the recommendation for a more modern design that is
>all carbon fiber? The carbon is conductive, but absorbs radiation
>instead of reflecting it from what I understand. Go with a foil
>circle or strips of the appropriate diameter on the outside of the
>carbon, but under the paint?
That's a whole other can of worms. The carbon fiber
is, as you've described, pretty lossy stuff. Yeah, it
is conductive but much of electrical energy flowing
through a carbon matrix is converted to heat.
Trying to create idealized ground planes over the
carbon and under the paint is exceedingly expensive
and problematic for affecting structural integrity
of the shell.
At HBC, non-resonant ground planes were bonded to the
inside surface of the fuselage shell. Relatively
inexpensive and the flight test results deemed them
adequate to the task.
Bob . . .
Message 11
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Subject: | Re: Speakers for helmet installation |
Eric, I've flown with the Com-tronics helmet when I was getting my WSC
endorsement. It was all right, but I have a reason for wanting the Shoei.
They have saved my life once and my looks twice. In every incident, the
helmet took the blow and I escaped without so much as a headache. So you
can understand why I like having a jaw bar that I know will keep the ground
and debris away from my mug.
Rick
On Thu, Feb 28, 2013 at 10:12 AM, Eric M. Jones <emjones@charter.net> wrote:
> emjones@charter.net>
>
>
> > All, I fly a trike wearing a full face Shoei helmet. While the helmet
> doesn't seal my ears like headphones ........... Can anyone recommend a
> particular speaker or mic cartridge that has worked for you?
> > Rick Girard
>
>
> Dear Rick,
>
> Not only is there technical skill on this website, but good advice too, I
> hope.
>
> The problem you are having is called "Target Fixation". What you need to
> do is sit down and imagine how to get where you want to be without adding
> unnecessary restraints such as "finding a use for a Shoei helmet". Or in
> other words, use the right tool for the job. There are helmets with built
> in headphones and full face-shields too. No problem.
>
> One powerfull tool I have used is to just sell one device on Ebay and buy
> what you need there too.
>
> Bada bing bada boom....
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=395274#395274
>
>
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
Message 12
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Subject: | Ground plane diameter |
At 11:34 AM 2/28/2013, you wrote:
>Id like to try to answer this:
>
>300 million meters per second is roughly the
>speed of light also about the speed the radio
>waves propagate. Dividing this by the frequency
>in megahertz gives you the wave length. So
>300,000,000/127,500,000 = 2.35 meters.
>
>
>seems like this was on the test for my ham
>license surprising I still remember it!>
Yeah, pretty cool stuff. First learned to do those
calculations on a slide rule about 60 years
ago . . .
Bob . . .
Message 13
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Subject: | Re: Ground plane diameter |
I'd forgotten about a compendium of antenna articles
that were waiting to be posted to the website. I just
put them up where they can be downloaded and inquiring
minds can exploit as appropriate:
http://tinyurl.com/d2ql8lw
Bob . . .
Message 14
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Subject: | Re: Eye Beam Mini LED / RF interference |
Perihelion Design sells an extremely versatile LED light too.
See: www.PerihelionDesign.com
These are made from the Loc-Line snap together coolant line parts. Dimmers are
available too.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=395308#395308
Attachments:
http://forums.matronics.com//files/led_goosenecks_892.pdf
Message 15
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Subject: | Re: Speakers for helmet installation |
Have you tried a motorcycle intercom kit? There are several available (I
only have links for UK companies, but there must be a few stateside).
They typically supply small speakers that velcro into the helmet and a
microphone that glues into the chin bar with wires hidden behind the the
lining. Equally they have plugs that will disconnect easily when you
forget to unplug ...
Peter
On 27/02/2013 23:55, Richard Girard wrote:
> All, I fly a trike wearing a full face Shoei helmet. While the helmet
> doesn't seal my ears like headphones it does cut down the noise
> considerably. It also cuts out my ability to hear my radio so I want
> to put speakers and a small mic in the helmet. I did this once before
> cannabalizing a Cobra VOX family radio for hang gliding. I don't want
> to cannabalize my David Clarks this time so the speakers and mic will
> be compatible with my hand held (a Vertex). Mouser has lots of mylar
> diaphragm speakers of the right size and depth. Can anyone recommend a
> particular speaker or mic cartridge that has worked for you?
>
> Rick Girard
> Do not archive
>
> --
> Zulu Delta
> Mk IIIC
> Thanks, Homer GBYM
>
> It isn't necessary to have relatives in Kansas City in order to be
> unhappy.
> - Groucho Marx
>
> *
>
>
> *
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