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All Internal Antennas

Gsuit

Gsuit

Well Known Member
Hey,

I'm getting all of my radios together to do it in one big push and I have some questions concerning antennas that I couldn't find in the archives: Can you have all internal antennas, or are there some that only come in external forms? What are those antennas, and where can I find them? Here's my list of avionics:
- GMA340
- SL-30
- GN430
- GTX327

plus: GRT's w/ XM weather and ACK ELT

I see on Aircraft Spruce's website they list 3 types of Archer antennas; VOR, COM, and one generic "11-21015-2 WING TIP ANTENNA SA-001-2"... what's the 3rd one for?
 
Yes

Hi Clayton,
Yes, you can have all of your antennas mounted internally but I would be careful with the Comm antenna. That's the only one we have underbelly because we didn't want any compromise in clarity with air traffic controllers. The belly is also a good counterpoise for transmissions. Some guys with wingtip mounted comms have had difficulties when the tower is on the opposite side of the airplane....apparently the transmissions were shielded by the mass of the airplane. Besides, one antenna underbelly might cost you 1/4 MPH. :) The Archer antennas work well in the tips.

Regards,
Pierre
 
Internal comm antenna......bad idea
Internal Nav antenna........marginal idea
Internal GPS antenna........doable, but why not put it right behind the canopy
Internal TPX antenna........bad idea

All hidden antennas are compromises, for very little performance gain.
 
Windscreen foil?

Was just reading my 24 Years of the RVator last night. There was a section in there that talked about internal antenna's. Van's has (at least, when this came out in the RVator) had good luck with a foil antenna (comm) that comes out of the glareshield and then up the middle of the windscreen. Not sure you'd want to do this on a tip up, but for a slider it might be an option. The article claimed quite good reception from as much as 100 mi. out. Wingtip antenna's didn't prove to be as good... easier to do nav in the tips because of the horizontal plane.

Other than the RVator article, I haven't heard much talk of this option. Anyone with direct real world experience?
 
I think the 2 replies are assuming different things. Pierre's response is assuming by "internal" you mean in the wingtips which are made of fiberglass and are essentially "invisible" to RF.

Yukon's post seems to assume, as did my understanding of your query, that you want to mount your antennas internally to the metal structure of the aircraft, like inside the fuselage. That's a bad idea because metal will block almost all (if not all) the RF coming out of your antennas.

I'm going to mount my transponder antenna and comm antenna on the bottom (outside) of the fuse. I'll put in a Nav antenna in the wingtip and the GPS antenna on the top of the fuse, behind the canopy.
 
Gsuit,

I went through the same thought process on antennas about 3 yrs ago while building my 9a. This is what I ended up with:

Comm Antenna -- on the belly center between main spar and flap motor--works extremely well.

GPS antenna--special mount was made to attach to the motor mount, right side, just inboard of the oil stick access door. Reception under the fg cowl is excellent with no drop outs in 1.5 years. It is driving a GNS430.

VOR/GS antenna is the archer type mounted in the left wingtip. When using the same airport to practice IFR approaches as I used with my old Mooney 201 (tail mounted towel bar antenna) I find little to no range difference as to when the GS/localizer becomes active.

Transponder, marker beacon antennas are the low drag type (boat) and are mounted along the belly center line aft of the baggage area.

If I had it to do over again I would probably use an Archer style MB antenna mounted in a wingtip based on the good results from the VOR/GS antenna.

Hope this helps!

Cheers,

db
 
...clarification

Sorry about any confusion. When I say "internal" I'm referring to anywhere the antenna is not on the outside of the airplane, whether it be wingtip or fuselage, etc.

I'm not really trying to re-invent the wheel, but it seems most RV's have things internal, or at least mounted in a way that isn't visible from ground photos or even formation pics.

Obviously reception matters to me, but if it is being done to a satisfactory level with internal comm / nav antennas, then that's the way I'd like to go.

As a side question, what are all of the antennas I'll need?
 
lostpilot28 said:
I think the 2 replies are assuming different things. Pierre's response is assuming by "internal" you mean in the wingtips which are made of fiberglass and are essentially "invisible" to RF.

Yukon's post seems to assume, as did my understanding of your query, that you want to mount your antennas internally to the metal structure of the aircraft, like inside the fuselage. That's a bad idea because metal will block almost all (if not all) the RF coming out of your antennas.

I'm going to mount my transponder antenna and comm antenna on the bottom (outside) of the fuse. I'll put in a Nav antenna in the wingtip and the GPS antenna on the top of the fuse, behind the canopy.
Click to expand...

No, I'm assuming inside of the tips......but don't forget, the fiberglass tips have metal airplane on one side of them. Good comm and nav is more important to me than 1/2 a knot.
 
I'd say that most RVs have "external" COMM and TXP antennas.. though Archer NAV in wingtip has been a popular choice...

Luckily, under-belly antennas are not really in plain sight (sounds like you missed them?) and they sure work fine.
 
yes and no

Garmin 340, 430, SL40, 330S

The MB antenna is copper foil in the wing tip. Works okay.

Comm in the 430 is a bellymounted antenna. Works great. GPS antenna under the cowl. Works great. VOR antenna in Wing tip (Archer) reception is weak.

SL40 Comm 2, Archer wing tip antenna. Works pretty good.

330S, belly mounted antenna, Works great.

My suggestion, main comm on belly. Transponder on belly. Main nav exposed somewhere.
 
Here is another opinion

One archer Nav wing tip antenna
attached to GNS 430 and SL30 through a splitter.

One 40 inch unshielded piece of coax
connected to the PM6000M marker beacon.

One bent-whip belly mounted Comm antenna mounted under the pilots seat
connected to the GNS 430 comm.

One transponder boat antenna mounted to the belly under the passenger seat
connected to (you guessed it) the transponder.

One Archer Comm wing tip antenna
connected to the SL30 comm.

Three GPS antenna mounted under the cowl about three inches before the firewall.
connected to GNS 430, BMA EFIS Sport and BMA EFIS Lite.

The Nav operation on both the SL30 and GNS 430 work as good as any plane I have ever flown.
The marker antenna works great.
The GNS 430 comm has twice the range as the SL30.
All the GPS units work great.

I have seen someone plane that mounted the short pole type transponder under the back of the cowl (near the exhaust pipes) and claimed that it work great. I though about doing this, but decided against because my plane looked a little crowded in this area.

If I were doing it over again, I would not bother with the Archer comm antenna and just split the bent-whip comm between the two radios.

Kent
 
GPS on the glareshield & hidden aux antennas

You don't want to spend that much on radios and then get lousy reception because of the antennas.

I've got a bent whip COM and a blade transponder antenna under the belly. My Nav antenna is an Archer in the wingtip, but although it works fine, I've never actually used it since I'm never got around to going for my IFR ticket. My GPS antenna is on the glareshield and works great, but my flying buddies complain that the reflection on the windshield (it's on their side) ruins the view. You for sure wouldn't want it on the left side.

I've also got two auxilary hidden antennas, one in each main gear fairing. They're just a length of coax with 22" of shielding stripped off. I use one for my FM receiver and the other for a handheld COM. They work well for the intended purpose, but I would never consider using them to feed that 430.
 
RV7Guy said:
Garmin 340, 430, SL40, 330S

Comm in the 430 is a bellymounted antenna. Works great. GPS antenna under the cowl. Works great. VOR antenna in Wing tip (Archer) reception is weak.


My suggestion, main comm on belly. Transponder on belly. Main nav exposed somewhere.
Click to expand...

My experience with the Archer wingtip NAV antenna has been excellent. I have better VOR reception (sl30, Archer antenna) and performance than the certified aircraft I also fly (Cirrus SR22, C337). You might want to troubleshoot if you're having weak reception. I have specifically looked for shadowing (none that I can detect) and typically pick up VORs at 100NM or so at cruise altitudes.

The MB antenna can be pretty much anywhere--it's a strong signal and you're right on top of the station while receiving it.

I agree with the posts suggesting the Comm and transponder antennas should be external, although I have talked to at least one RV-8 owner (John Huft maybe?) who put a transponder antenna in the back of one wheelpant, and a "rubber ducky" comm antenna in the other with good results.

I know of one RV-6A that had a copper foil comm antenna in a main gear fairing. That worked pretty well most of the time, but he had a significant "dead spot" in the radiation pattern that sometimes caused him trouble on the ground, talking to the tower. Occasionally he would have to turn the airplane 30 degrees or so at the hold short line to be able to pick up his clearance.
 
db1yg said:
......If I had it to do over again I would probably use an Archer style MB antenna mounted in a wingtip based on the good results from the VOR/GS antenna.....
Click to expand...
I agree completely. My Archer wingtip mounted VOR/GS and marker beacon antennas work just as good as any traditional installations I have ever flown. In flight, I have intentionally positioned the RV's wingtip in an attempt to obscure a ground based VOR station broadcast and have yet to lose a signal. I mounted the comm and transponder ants on the belly for optimum performance and have not heard anything other than "loud and clear" with radio checks. I'm glad I hid the GPS antenna under the cowl where it has performed without fail. Its antenna cable is less than 14" to the back of the radio stack.
 
ELT

If anyone mentioned the ELT I missed it. I copied Roberta's solution on my tip-up. I've also heard of them under the tail intersection fairing.

My Archer Nav antenna in the wingtip is, with the SL-30, the best I've ever experienced, so good enough.

My Archer Comm antenna in the wingtip even though I mounted it at the best available angle toward vertical was simply inadequate and I put in a Comant on the belly which is very good.
 
ELTs are TSO'd and must be installed per the installation manual. Most installation manuals call for the antenna to be mounted externally and within 30 degrees of vertical.
 
ELT requirements?

Mel said:
ELTs are TSO'd and must be installed per the installation manual. Most installation manuals call for the antenna to be mounted externally and within 30 degrees of vertical.
Click to expand...
I know they are TSO'd, but what makes it necessary on an experimental to do as you describe?
 
hevansrv7a said:
I know they are TSO'd, but what makes it necessary on an experimental to do as you describe?
Click to expand...
Because the TSO requires it. It is NOT exempt from experimentals. Same goes for the transponder.
 
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