Today's Message Index:
----------------------
1. 05:28 AM - Re: gps antenna under glassfibre? (bobnoffs)
2. 06:12 AM - Re: Re: gps antenna under glassfibre? (Robert L. Nuckolls, III)
3. 10:03 AM - Re: gps antenna under glassfibre? (rparigoris)
4. 01:07 PM - Re: Re: gps antenna under glassfibre? (Rowland Carson)
5. 01:33 PM - Re: Re: gps antenna under glassfibre? (Sebastien)
6. 03:31 PM - Re: Re: gps antenna under glassfibre? (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: gps antenna under glassfibre? |
what happens if the antennas are right next to each other? it absolutely will hurt
reception,or it might and it's not recommended? does anyone have experience
with 2 antennas next to each other?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=499321#499321
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| Subject: | Re: gps antenna under glassfibre? |
At 07:26 AM 11/9/2020, you wrote:
>
>what happens if the antennas are right next to each other? it
>absolutely will hurt reception,or it might and it's not recommended?
>does anyone have experience with 2 antennas next to each other?
>
Receive-only antennas at near microwave frequencies
are not interactive. They work fine in close proximity.
Bob . . .
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| Subject: | Re: gps antenna under glassfibre? |
Hi Rowland I have a XS mono I already had most of my antennas installed and needed
to add ADS-B. The Garmin GA-35 antenna install manual wants a ground plane
(Bob can't quite figure out why). Anyway I have a Dynon magnetometer in my ceiling
and the GA-35 would need a clearance pocket if I did install in ceiling.
Anyway I made up a 8 pointed ground plane that will also be used as an antenna
mount and installing it just forward of the baggage bay bulkhead under the top
of fuse. I will not install it absolute level with fuse but aim the forward
up a little. Looks not too bad. https://1drv.ms/u/s!Ah1S270Nwg9V3SI7_BpEe0ECaWIV?e=cVFSGb
I will bend radials fto follow the bottom of ceiling except for the
front ones. The front facing radial will be ~ 2 fingers below the ceiling.Ron
P.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=499323#499323
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| Subject: | Re: gps antenna under glassfibre? |
On 2020-11-09, at 14:11, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com>
wrote:
> At 07:26 AM 11/9/2020, you wrote:
>> what happens if the antennas are right next to each other? it absolutely will
hurt reception,or it might and it's not recommended? does anyone have experience
with 2 antennas next to each other?
> Receive-only antennas at near microwave frequencies
> are not interactive. They work fine in close proximity.
Bob - that was my gut feeling too, but I poked around for quite some time and found
this spacing chart on the Garmin marine support area:
https://support.garmin.com/en-GB/marine/faq/2svIUDPSDa3M99GT2P1g09/
That was the basis for my 6/150mm spacing of the antennae already mounted on top
of my instrument module.
Since my earlier posting Ive been in touch with Trig support and they concur with
the Garmin advice. The Trig antenna is an active device and claims 26dB gain
over a passive antenna. I guess that some of the other ones are also active,
and that may be at least part of the reason for the spacing requirement.
Ive also slept on the question (often a good idea!) and realise that I can attach
the TA50 to a small bracket above the parcel shelf (in front of the P2 seat)
adjacent to the windscreen edge and that will be fine for both sky view and
spacing, although perhaps not the ultimate in elegance!
So, I have this day ordered a TN72/TA50 combo and look forward to getting my 50%
CAA rebate on the cast.
Thanks for all the thoughtful responses.
in friendship
Rowland
| Rowland Carson ... that's Rowland with a 'w' ...
| <rowlandcarson@gmail.com> http://www.rowlandcarson.org.uk
| Skype, Twitter: rowland_carson Facebook: Rowland Carson
Message 5
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| Subject: | Re: gps antenna under glassfibre? |
Garmin, Dynon, Trig, and Stratus all state in their installation manuals
that GPS antennas must be 6" apart.
I have seen many, many GPS antennas sitting right next to each other
working just fine but if I was building a new plane, I would try very hard
to follow the installation manuals.
On Mon, Nov 9, 2020 at 1:18 PM Rowland Carson <rowlandcarson@gmail.com>
wrote:
> rowlandcarson@gmail.com>
>
> On 2020-11-09, at 14:11, Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
> > At 07:26 AM 11/9/2020, you wrote:
>
> >> what happens if the antennas are right next to each other? it
> absolutely will hurt reception,or it might and it's not recommended? does
> anyone have experience with 2 antennas next to each other?
>
> > Receive-only antennas at near microwave frequencies
> > are not interactive. They work fine in close proximity.
>
> Bob - that was my gut feeling too, but I poked around for quite some time
> and found this spacing chart on the Garmin marine support area:
>
> https://support.garmin.com/en-GB/marine/faq/2svIUDPSDa3M99GT2P1g09/
>
> That was the basis for my 6=9D/150mm spacing of the antennae alread
y mounted
> on top of my instrument module.
>
> Since my earlier posting I=99ve been in touch with Trig support and
they
> concur with the Garmin advice. The Trig antenna is an active device and
> claims 26dB gain over a passive antenna. I guess that some of the other
> ones are also active, and that may be at least part of the reason for the
> spacing requirement.
>
> I=99ve also slept on the question (often a good idea!) and realise
that I
> can attach the TA50 to a small bracket above the parcel shelf (in front o
f
> the P2 seat) adjacent to the windscreen edge and that will be fine for bo
th
> sky view and spacing, although perhaps not the ultimate in elegance!
>
> So, I have this day ordered a TN72/TA50 combo and look forward to getting
> my 50% CAA rebate on the cast.
>
> Thanks for all the thoughtful responses.
>
> in friendship
>
> Rowland
>
>
>
===========
===========
===========
===========
===========
>
>
Message 6
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| Subject: | Re: gps antenna under glassfibre? |
>Since my earlier posting I=99ve been in touch
>with Trig support and they concur with the
>Garmin advice. The Trig antenna is an active
>device and claims 26dB gain over a passive
>antenna. I guess that some of the other ones are
>also active, and that may be at least part of
>the reason for the spacing requirement.
That would be a very interesting hypothesis to explore.
To be sure, there are active devices (transistors)
in these devices but I cannot wrap my head around the
idea that they 'radiate' any energy that would cause
them to compete for real estate.
Sometimes I wish I still had a desk out at Beech . . .
I could often get right to the horse's mouth with
a phone call to the big guys in avionics . . . King
radio was always VERY helpful and forthcoming.
It was King engineer that first confirmed my own
studies suggesting that (1) radio killing spikes
do not exist in vehicular DC power systems and
(2) qualification testing of all avionics since
the 80's has to PROVE that an appliance stands
off EVERYTHING the airplane might throw at it.
I.e. avionics master switches were ill-conceived.
I might know a guy at Garmin that either knows
or can find out what physics drives that spacing
suggestion for non-radiating antennas.
You could do the experiment yourself. Put two
sets of mounting holes for the 2nd antenna . . .
one 'snuggled up' to the first and the second
one 'socially distanced'. See if you can observe
any differences.
Bob . . .
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