Do I need two nav antennae?

[RandyAB]

I installed a cat whisker antenna on top of the VS for VOR/GS. I was talking about antenna placement with friend who is an electrical engineer and he said he installed both a cat whisker and an Archer wing tip antenna for each of his two nav radios so that he didn't have to split the signal.

Is signal loss with a splitter that significant that I should be thinking about two seperate antennae?

[Carl Froehlich]

Originally Posted by RandyAB

I installed a cat whisker antenna on top of the VS for VOR/GS. I was talking about antenna placement with friend who is an electrical engineer and he said he installed both a cat whisker and an Archer wing tip antenna for each of his two nav radios so that he didn't have to split the signal.

Is signal loss with a splitter that significant that I should be thinking about two seperate antennae?

Short answer - no.

Carl

[Jesse]

You can use a splitter. That is standard practice.

[noelf]

Well, it sort of depends. In the case of a Garmin SL-30 nav/com, there is an internal splitter that sends 1/2 of the received signal to the navy receiver and the other 1/2 to the loc-gs function.

Other radios have separate nav and gs antenna inputs. In that case, you need a splitter if you only have one vor antenna. Or if you have multiple nav/gs receivers.

Each time you go through a splitter, the signal gets cut in half (or 3db). Using one splitter is not a big deal. The gs/loc signal is used when "close" to the airport environment and the VOR transmitters put out a much stronger signal for distance reception.

Another factor in our favor is that our modern receivers are very sensitive and can receive fainter /weaker signals than receivers of yesterday.

Another factor in received signal strength is antenna design and placement, but that is a different subject.

[rv7charlie]

If you're splitting signal between two straight up nav radios, each gets 50%, but the glide slope tuner is a different frequency, so it's not using any of the energy from the nav signal. Should be only slight insertion loss for the splitter.

Only real downside to using a splitter would be, if you want full redundancy for IFR you'd need to duplicate the antennas.

[RV7A Flyer]

If you're splitting one signal to a separate VOR/LOC and GS antenna inputs, such as on a GNS430, you want to use a *diplexer*, not just a splitter.

http://www.aircraftspruce.com/catalo...clickkey=11684

[N941WR]

Many builders have had good results with the archer antenna, when installed properly. Here is a thread on the subject.

It sounds like it is too late for you though.

[rv7charlie]

Originally Posted by RV7A Flyer

If you're splitting one signal to a separate VOR/LOC and GS antenna inputs, such as on a GNS430, you want to use a *diplexer*, not just a splitter.

http://www.aircraftspruce.com/catalo...clickkey=11684

Exactly right; I got lazy when typing my answer earlier. And if you look to the right on that product page, you'll see variations on that theme, including models with 2 VOR outputs and 1 or 2 glide slope outputs.

[GalinHdz]

Do you NEED two Nav antennas? No. But IMHO if you can install two without much effort then yes. YMMV

[maniago]

A diplexer combines or splits a signal based on frequency. A splitter splits all signal frequencies it can see. Use the right one....in your case a diplexer. But check the freqs and applications.
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Ooops. Read this - all the above appears to be wrong wrt your question. http://www.vansairforce.com/communit...ad.php?t=26063

Its not a spitter or a diplexer. Triplexer? T joint and diplexer? Yikes. Stein has some good comments on the thread above.....