NAV Antenna recommendation solicitation

[Pounder]

Hello VAF..

Looking for recommendations for NAV antenna setup for two VOR/ILS receivers. I'm installing an IFD540 and a VAL INS429 in RV8
- I’m thinking an antenna in a wingtip would be cleanest.
Q might this choice be a compromise or in anyway less “functional” than traditional external antenna?
- I believe I can split signal from one antenna to both receivers.
Q Might this result in signal compromise, or any sort of degradation as opposed to installing an antenna for each receiver?

Q I believe a duplexer (?) is the required device for inputting LOC and GS info to respective receivers. Is there a preferable make/model?

- the VAL has MB included.
Q is a MB antenna necessary, or can that signal also be derived from NAV antenna?

I love and appreciate the plethora of knowledge and experience in this group.
If you’ve read this far, thanks!!

Bryan

 

[BobTurner]

Hello VAF..

Looking for recommendations for NAV antenna setup for two VOR/ILS receivers. I'm installing an IFD540 and a VAL INS429 in RV8
- I’m thinking an antenna in a wingtip would be cleanest.
Q might this choice be a compromise or in anyway less “functional” than traditional external antenna?
- I believe I can split signal from one antenna to both receivers.
Q Might this result in signal compromise, or any sort of degradation as opposed to installing an antenna for each receiver?

Q I believe a duplexer (?) is the required device for inputting LOC and GS info to respective receivers. Is there a preferable make/model?

- the VAL has MB included.
Q is a MB antenna necessary, or can that signal also be derived from NAV antenna?

I love and appreciate the plethora of knowledge and experience in this group.
If you’ve read this far, thanks!!

Bryan

1. Yes, a wingtip (‘Archer’) antenna is ‘cleaner’. Gain 0.2 knots over an external antenna. No danger of poking out your or your dog’s eye.
2. A good external antenna will pull in a distant signal better than the Archer, especially when the path to the vor is thru the fuselage (vor station 90 deg to the nose). But I’m talking over 80 nm away. Is that really a requirement?
3. Splitting the signal in two cuts the strength by two. But it also cuts any external noise (‘static’) in half. So it’s only a real concern if you’re limited by the internal noise generated by the receiver. If you’re concerned, put an Archer in each wingtip, run one to nav 1, the other to nav2 (Do not connect them together). This is pretty much a wash cost-wise, as the second antenna costs about the same as the splitter (which you don’t need with two antennas).
4. I do not know if your radios require external diplexers (split vor/loc out from GS). Some radios do this internally. Is there a separate antenna input for GS on your radios?
5.What’s a MB? Seriously, they are going the way of the do-do. But they’re at 75 MHz, bad mis-match for the 110 MHz nav antenna. OTOH the transmitter is very close to you in practice. Almost any wire laying in the bottom of the engine cowling will work okay as an MB antenna.

Get some advice on how to best install the Archer(s).

 

[Pounder]

1. Yes, a wingtip (‘Archer’) antenna is ‘cleaner’. Gain 0.2 knots over an external antenna. No danger of poking out your or your dog’s eye.
2. A good external antenna will pull in a distant signal better than the Archer, especially when the path to the vor is thru the fuselage (vor station 90 deg to the nose). But I’m talking over 80 nm away. Is that really a requirement?
3. Splitting the signal in two cuts the strength by two. But it also cuts any external noise (‘static’) in half. So it’s only a real concern if you’re limited by the internal noise generated by the receiver. If you’re concerned, put an Archer in each wingtip, run one to nav 1, the other to nav2 (Do not connect them together). This is pretty much a wash cost-wise, as the second antenna costs about the same as the splitter (which you don’t need with two antennas).
4. I do not know if your radios require external diplexers (split vor/loc out from GS). Some radios do this internally. Is there a separate antenna input for GS on your radios?
5.What’s a MB? Seriously, they are going the way of the do-do. But they’re at 75 MHz, bad mis-match for the 110 MHz nav antenna. OTOH the transmitter is very close to you in practice. Almost any wire laying in the bottom of the engine cowling will work okay as an MB antenna.

Get some advice on how to best install the Archer(s).

Outstanding. Thanks Bob.

I’m on it, probably, with an antenna in each wing tip.

 

[BobTurner]

Outstanding. Thanks Bob.

I’m on it, probably, with an antenna in each wing tip.

I just looked it up. Both your nav radios have a separate GS antenna input (no internal diplexer) so you'll need a pair of diplexers to split off the GS signals prior to the back of the nav's.

 

[bjdecker]

Hello VAF..

Looking for recommendations for NAV antenna setup for two VOR/ILS receivers. I'm installing an IFD540 and a VAL INS429 in RV8
- I’m thinking an antenna in a wingtip would be cleanest.
Q might this choice be a compromise or in anyway less “functional” than traditional external antenna?
- I believe I can split signal from one antenna to both receivers.
Q Might this result in signal compromise, or any sort of degradation as opposed to installing an antenna for each receiver?

Q I believe a duplexer (?) is the required device for inputting LOC and GS info to respective receivers. Is there a preferable make/model?

- the VAL has MB included.
Q is a MB antenna necessary, or can that signal also be derived from NAV antenna?

I love and appreciate the plethora of knowledge and experience in this group.
If you’ve read this far, thanks!!

Bryan

Make your own "Archer" antenna -- dimensions attached.



Add a 7" x 0.375" x 0.025" "stub" under the top plastic screw to optimize GS reception (329 - 335MHz)



A good splitter is a Minicircuits ZFSC-3-1+, full bandwidth (read: frequencies) passed to all 3 ports -- no pesky "notch" or hi/lo pass like with the Comant splitter/diplexer. Good isolation across all ports.

 

[N184DA]

Hello VAF..

Looking for recommendations for NAV antenna setup for two VOR/ILS receivers. I'm installing an IFD540 and a VAL INS429 in RV8
- I’m thinking an antenna in a wingtip would be cleanest.
Q might this choice be a compromise or in anyway less “functional” than traditional external antenna?
- I believe I can split signal from one antenna to both receivers.
Q Might this result in signal compromise, or any sort of degradation as opposed to installing an antenna for each receiver?

Q I believe a duplexer (?) is the required device for inputting LOC and GS info to respective receivers. Is there a preferable make/model?

- the VAL has MB included.
Q is a MB antenna necessary, or can that signal also be derived from NAV antenna?

I love and appreciate the plethora of knowledge and experience in this group.
If you’ve read this far, thanks!!

Bryan

I installed an Archer in the wingtip of ny 4. I had an original version of the Narco NAV-122, which is everything (VOR/LOC/GS/MB) in one very long 3 1/8” box.
The Archer drove everything and it worked fine. As someone here mentioned, the MB transmitters are directional and designed to work when you are directly over the top so I’m thinking almost anything would work. In my case, the Archer was sufficient.

As for a splitter, my NAV-122 came with a Narco splitter, specifically designed to fit on the back of the Nav and matched mechanically with all of the ant connectors simultaneously. From there, I ran a single coax to the Archer.

 

[bjdecker]

I installed an Archer in the wingtip of ny 4. I had an original version of the Narco NAV-122, which is everything (VOR/LOC/GS/MB) in one very long 3 1/8” box.
The Archer drove everything and it worked fine. As someone here mentioned, the MB transmitters are directional and designed to work when you are directly over the top so I’m thinking almost anything would work. In my case, the Archer was sufficient.

As for a splitter, my NAV-122 came with a Narco splitter, specifically designed to fit on the back of the Nav and matched mechanically with all of the ant connectors simultaneously. From there, I ran a single coax to the Archer.

For reference --
MB -=> 75MHz -- 3W
VOR/LOC -=> 108 - 118MHz, 50W (VOR-L, T) to >250W (VOR-H)
GS -=> 329 - 335MHz -- <5W

In order to use a single antenna with its output split among many receivers you should use a splitter that has full band pass thru capabilities (see earlier post ref. Mini-circuits ZFSC-3-1+) -- 1 - 500MHz is sufficient.

The classic Archer antenna is optimized (and can be tuned further) for VOR/LOC frequencies - a low SWR (<2:1) and impedance matched to the coax feed (~50Ω). The GS frequencies show about 5:1 SWR and MB is 7:1 or so with impedances all over the map (the matching capacitor is too large/too small for those frequencies)*

Without modification, the GS frequencies are received pretty well, but the splitter loss (>5dB) can become problematic if you're trying to receive the GS beyond the service area (10 miles).

Similarly, MB works pretty well; Sort of like driving over a speed bump at night -- The antenna won't see it (VSWR, Impedance), but the receiver is still going to feel it.

 

[Pounder]

For reference --
MB -=> 75MHz -- 3W
VOR/LOC -=> 108 - 118MHz, 50W (VOR-L, T) to >250W (VOR-H)
GS -=> 329 - 335MHz -- <5W

In order to use a single antenna with its output split among many receivers you should use a splitter that has full band pass thru capabilities (see earlier post ref. Mini-circuits ZFSC-3-1+) -- 1 - 500MHz is sufficient.

The classic Archer antenna is optimized (and can be tuned further) for VOR/LOC frequencies - a low SWR (<2:1) and impedance matched to the coax feed (~50Ω). The GS frequencies show about 5:1 SWR and MB is 7:1 or so with impedances all over the map (the matching capacitor is too large/too small for those frequencies)*

Without modification, the GS frequencies are received pretty well, but the splitter loss (>5dB) can become problematic if you're trying to receive the GS beyond the service area (10 miles).

Similarly, MB works pretty well; Sort of like driving over a speed bump at night -- The antenna won't see it (VSWR, Impedance), but the receiver is still going to feel it.

BJD, then it seem for best performance i should install one antenna per receiver.

 

[bjdecker]

BJD, then it seem for best performance i should install one antenna per receiver.

Best? Sure.
Adequate to the mission, it’s overkill.