Dipole Transponder Antennas

[Tony Condon[_2_]]

Has anyone used a Dipole antenna on their transponder? I understand that
the dipole gives better coverage above where the "standard" antennas
usually only project down and to the sides. Aircraft Spruce carries
dipoles, they are a little spendy, but might be worth it. Any experience
out there?
-Tony Condon
Cherokee II N373Y

[jcarlyle]

There are a number of people in this group who used dipole antennas.
I've got the L2 model from Advanced Aircraft Electronics in my ASW-19,
it was $99 if I remember right.

Because I have a fiberglass tail boom, all I had to do was glue the
dipole to the supplied strip of balsa, then glue the dipole into the
tail boom in a vertical position. No need for a ground plane at all,
and as you point out it radiates both upwards and downwards.

It seems to work very well, but I couldn't tell you just how much
better it performs than a monopole under the same circumstances. For
me its biggest advantage was the ease of installation.

-John

Tony Condon wrote:
> Has anyone used a Dipole antenna on their transponder? I understand that
> the dipole gives better coverage above where the "standard" antennas
> usually only project down and to the sides. Aircraft Spruce carries
> dipoles, they are a little spendy, but might be worth it. Any experience
> out there?
> -Tony Condon
> Cherokee II N373Y

[Bob Backer]

+1

Works great, easy to install. W & W has them too.

jcarlyle wrote:
> There are a number of people in this group who used dipole antennas.
> I've got the L2 model from Advanced Aircraft Electronics in my ASW-19,
> it was $99 if I remember right.
>
> Because I have a fiberglass tail boom, all I had to do was glue the
> dipole to the supplied strip of balsa, then glue the dipole into the
> tail boom in a vertical position. No need for a ground plane at all,
> and as you point out it radiates both upwards and downwards.
>
> It seems to work very well, but I couldn't tell you just how much
> better it performs than a monopole under the same circumstances. For
> me its biggest advantage was the ease of installation.
>
> -John
>
> Tony Condon wrote:
>> Has anyone used a Dipole antenna on their transponder? I understand that
>> the dipole gives better coverage above where the "standard" antennas
>> usually only project down and to the sides. Aircraft Spruce carries
>> dipoles, they are a little spendy, but might be worth it. Any experience
>> out there?
>> -Tony Condon
>> Cherokee II N373Y

[Brian Bange[_2_]]

I had the same experience with this antenna. In your wooden
ship this is just the ticket. I bought mine from Tim at Wings and
Wheels. Works great and is super easy to install.
Brian

At 20:36 14 April 2009, jcarlyle wrote:
>There are a number of people in this group who used dipole
antennas.
>I've got the L2 model from Advanced Aircraft Electronics in my
ASW-19,
>it was $99 if I remember right.
>
>Because I have a fiberglass tail boom, all I had to do was glue
the
>dipole to the supplied strip of balsa, then glue the dipole into
the
>tail boom in a vertical position. No need for a ground plane at
all,
>and as you point out it radiates both upwards and downwards.
>
>It seems to work very well, but I couldn't tell you just how
much
>better it performs than a monopole under the same
circumstances. For
>me its biggest advantage was the ease of installation.
>
>-John
>
>Tony Condon wrote:
>> Has anyone used a Dipole antenna on their transponder? I
understand that
>> the dipole gives better coverage above where the
"standard" antennas
>> usually only project down and to the sides. Aircraft Spruce
carries
>> dipoles, they are a little spendy, but might be worth it. Any
>experience
>> out there?
>> -Tony Condon
>> Cherokee II N373Y
>

[Tony Condon[_2_]]

Thanks,

after seeing the ones that Tim has, it makes more sense. The antennas
that Aircraft Spruce carries are different, and I cant see as well how
they mount. Will be very easy to mount that antenna in the web of sticks
in the tail of the Cherokee.
-Tony Condon
Cherokee II N373Y

[[email protected]]

I have use an L2 in my LS8 for five years. Just slap it on the inside
of the fuse with velcro. Works super. Approach reads me clearly in
all orientations.

[Frank[_1_]]

On Apr 14, 4:15*pm, Tony Condon >
wrote:
> Has anyone used a Dipole antenna on their transponder? I understand that
> the dipole gives better coverage above where the "standard" antennas
> usually only project down and to the sides. *Aircraft Spruce carries
> dipoles, they are a little spendy, but might be worth it. *Any experience
> out there?
> -Tony Condon
> Cherokee II N373Y

A dipole and a monopole with a proper groundplane both have
approximately the same pattern, both above and below the plane of the
groundplane. The whole idea of a 'groundplane' is to produce a
virtual mirror image of the monopole. Monopole/groudplane
combinations are particularly convenient for metal-skinned aircraft,
where the requisite groundplane is essentially free. A dipole
arrangement might be much simpler than a monopole/groundplane for a
glider.

Frank(TA)

[Eric Greenwell]

Frank wrote:
> On Apr 14, 4:15 pm, Tony Condon >
> wrote:
>> Has anyone used a Dipole antenna on their transponder? I understand that
>> the dipole gives better coverage above where the "standard" antennas
>> usually only project down and to the sides. Aircraft Spruce carries
>> dipoles, they are a little spendy, but might be worth it. Any experience
>> out there?
>> -Tony Condon
>> Cherokee II N373Y
>
> A dipole and a monopole with a proper groundplane both have
> approximately the same pattern, both above and below the plane of the
> groundplane. The whole idea of a 'groundplane' is to produce a
> virtual mirror image of the monopole. Monopole/groudplane
> combinations are particularly convenient for metal-skinned aircraft,
> where the requisite groundplane is essentially free. A dipole
> arrangement might be much simpler than a monopole/groundplane for a
> glider.

The patterns are different, and the bigger the ground plane, the bigger
the difference. The monopole with a large ground plane radiates only on
the side with the antenna. The "mirror image" you mention is just a
convenient way to think about how a conducting surface affects the
electric field. In practice, it blocks the field. Look up "Faraday
cage", as an example.

If a metal airplane needs a good signal on the top and the bottom, it
uses two antennas, one on each side. In Tony's wood and fabric glider,
the dipole is an good choice.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org