What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

best antenna locations

charosenz

Well Known Member
I am close to being ready to drill for antenna locations. Here is my plan. I would appreciate some feedback.

1) Comm = Belly aft of baggage firewall.
2) GPS puck = mount on glareshield, or forward on firewall under cowl
3) Transponder = Belly just inboard of right fuel vent
4) ADSB out = Belly just inboard of left fuel vent.
5) ADSB in Strautux = Tough one. May be vertical on side just aft of panel (love to hear from anyone who has the antennas mounted remote. Also to hear experience of anyone with these antenna horizontal. I know it is not recommended or ideal, but nonetheless, I would like to hear from anyone who has actually tried it.
6) ELT + Just forward of VS. May be belly just below the VS.

Any tips on passing the wingspar appreciated.

If you willing to share personal experience (good or bad) that would be great.

Thank you.
 
Charlie,

Your thinking is sound.

Important question: What type of ADS-B out system are you using? I ask this to get the belly antenna count right (and keep my advice from turning your belly into a porcupine of transponder antennas).

I assume your Stratux is like the others I have where there are two plastic stick antennas on the side, one for UAT 978 Mhz and another for 1090 Mhz.

I recently installed a Stratux hidden behind the panel in a friend's 4-seat legacy aircraft. At the same time I installed a GDL 82 to interface with his existing Garmin GTX Mode C transponder. So my belly antenna transponder-style antenna count from this was 3. Two for the Stratux and the original transponder antenna since the GDL 82 uses the original in conjunction with the original transponder unit. If you wanted to hide your Stratux away you too could mount it behind the panel or even aft of the baggage area or similar.

Specific to the Stratux: I installed two new Deltapop shark fin antennas on the belly, one UAT (978) and one transponder (1090). Ball and stick type antennas would work too but were not appropriate as this was a fast airplane where the drag is much lower with a shark fin profile vs the round ball and stick (and amazingly so for aircraft over 140 mph):
DSC01691.jpg


So paying attention to which antenna was which frequency type I ran double-shielded RG316 coax from each of these to the corresponding Stratux antenna connector on the unit. You can see which connector is which frequency when you open the Stratux box or do a test where you swap the original portable antennas and check the reception levels from the unit's IP address as outlined in Stratux instructions. I color coded the coax end connectors and component connectors with colored electrcians tape on each end so the next person wouldn't criss-cross them. The two new shark fins were installed on the aft belly on the centerline separated 8 inches on center "in trail". That was a good location to keep them at least a meter from any comm and the original transponder antenna. The double-shielded RG 316 coax I used for this has the same small diameter as the stuff that comes on Garmin's portable unit GPS pucks. Except Garmin uses RG 174 which isn't as good as my double-shielded RG 316, which has attenuation loss per foot very similar to RG 400. It's very easy to route being so thin. And light. I have strippers and connectors for RG 316 so I can install SMA, BNC, TNC connectors to it. For MCX installations I use the commercially available pigtails found online (similar to the one uAvionix ships with it's EchoUAT unit). You could skip all that specialty stuff and just use RG 400 per industry norm. There are SMA female and male connectors available for RG 400 and I would encourage the crimp type or 90 degree type where only one small solder joint is required. Or skip that too and get an adapter for conventional BNCs on eBay, the ones with the pigtails on them so as not to over-stress the Stratux connectors:
51t2%2BqzkMsL._AC_SL1001_.jpg


Since the Stratux wasn't exposed to the sky it's GPS signal had to be addressed. So to complete the picture I removed the USB GPS chip/antenna module from inside the Stratux and replaced it with a Vk-162 external USB puck receiver/antenna I bought online. This GPS puck was mounted to the glare shield with it's USB plug inserted into the Stratux in the same USB hub where I removed the original GPS module. Here is what the new Vk-162 GPS puck receiver looks like:
41ZdFHNIJYL._AC_.jpg




If you do mount the unit somewhere keep in mind it's orientation. Most Stratux units have an arrow on them showing which way is forward for the built-in attitude sensors. However, you can easily change this direction by re-setting it within it's IP address while standing it on end downward on whichever end is aft (or forward or something like that). Look it up online. It's easier than I can describe here.

And finally to power the Stratux get a micro USB 12 volt power cable with built-in 5V transformer hardwire power cord:
51BGlf3U4PL._AC_SL1000_.jpg



Too much information here probably.
 
Last edited:
1. Com. I assume a bent whip. Push the tail down and be sure the tail hits the ground before the antenna. If not you?ll need to move it forward until it clears. Watch out, these thing like to poke you in the eye when you least expect it. Top mounted whips work better on the ground at certain airports, ymmv.
2. GPS. If this is for vfr, throw it on the glare shield. Engine compartments get hot. If it?s for IFR then follow the TSO?d installation instructions, which call for external, on top, mounting.
3. And 4. Okay. Move each antenna one antenna length inboard from the edge, to give each a decent ground plane.
5. ADSB-in. I have 2 antennas for a Skyradar, one on each fiberglass door post/windscreen frame, vertical. Work fine in this location. Glareshield should also work.
6. ELT. Forward of VS is the recommended TSO position. Some try to protect it from a rollover by putting the antenna inside the VS fiberglass fairing. Less performance vs better survivability. You choose. Definitely not on the bottom of the plane, the satellites are ?up?. Unless you plan to always flip over.
 
antenna drag

Ball and stick type antennas would work too but were not appropriate as this was a fast airplane where the drag is much lower with a shark fin profile vs the round ball and stick (and amazingly so for aircraft over 140 mph)

Do you have a reference for this?
I found a reference of 0.41lbs @ 250mph from
https://www.rami.com/product/av-22/

but couldn't find any info on drag of the shark fin antennas.

(ooh I shoulda looked closer!)
https://www.rami.com/product/av-74/
It has a drag force of 0.09 lbs @ 250 mph"
 
Antenna locations

Jliltd, Bob,

First, thank you guys for your very informative quick replies.....

Jliltd,

As far as GPS-IN, I am planning on purchasing the stratux and yes they have two small antennas, one for 978 and one for 1090.

Honestly I had overlooked the internal GPS with the Stratux. So thanks for that reminder, and tip on external GPS remount. I will consider this.

(It bugs me to have to have a separate GPS for the ADSB IN and OUT. But I need the AHRS in the Stratux to feed the Foreflight....)

As far as ADSB-OUT I plan on purchasing the Echo UAT with SKYFYX GPS. (I will probably use RG400 with SMA, since I have a lot of that anyway.)

Nice step down volt converter, better than some I have seen, I just ordered one.

This is all going in my RV6A. I am not particularly concerned about the speed reduction of the small ball tip antennas for the transponder and ADSB out. They will probably go on the belly near the fuel vents with at least one antenna length distance like Bob mentioned. The other option is forward of the firewall on a small platform. I am not 100% sure about the clearance with the rudder pedals as they are not installed right now and even though the pedals were installed they were not rigged for travel limit yet.

Back to the antenna location......I only ask about the stratux because I really do not want to mount the stratux and Skyfyx GPS all on the glareshield of my RV6A. I am hoping to hear from some more RV folks to see what works best for them. To limit the population of the glareshield I may put the SKYFYX there, and mount the Stratux vertical on the side just aft of the panel with the antennas sticking up in to the canopy for visibility. I am curious how well the internal GPS will perform in this location. I do appreciate the info Jlitld about being able to remote the Stratux GPS. That is good to know. I will try to find some more details about this.

The horizontal aluminum channel that connects the top of the aft of the roll over bar to the fuse would be ideal location for the stratux but it would have to be upside down with the antennas horizontal, and that is just not ideal at all.

Great to learn from "been there done that" folks.

P.S. Bob, I will probably go with the ELT antenna on the top, but funny you mention crashing belly up. After seeing a few RV crash pics, there are many (my opinion only) of them that do end up belly up. Sad, but true.
 
Last edited:
Here's what i have done on my -9 and it has worked well for the past 13 years (5 with ADS-B), which may or may not work for your -6:

1) Comm = Just forward of the spar with the aft two screws bolted through the spar flange.
2) GPS puck = mount on glareshield - I have four GPS pucks mounted on my glairshield and have had no issues. Simple and short wire runs.
3) Transponder = On the belly, just aft of the firewall, on the right side, just inboard of the fuel vent. (same as you)
I have a SkyView setup so I have the Transponder antenna and one ADS-B antenna, which is identical to the transponder antenna
4) ADSB = On the belly, just inboard of the left fuel vent. (same as you)
5) ADSB in Strautux = see above.
6) ELT = I have a tip-up and mounted it just behind the roll bar with the antenna held in place with an adel clamp that secures the top end of it to the roll bar and keeps it from moving around.

All of the above works great, including the ELT, which I had activated and didn't notice until I got "the call".

With the above locations, all of your cable runs are short and easy to do with none of them going through the limited holes in the spar.
 
Last edited:
Bill,

Can you clarify where you mounted the Stratux box?


Here's what i have done on my -9 and it has worked well for the past 13 years (5 with ADS-B), which may or may not work for your -6:

1) Comm = Just forward of the spar with the aft two screws bolted through the spar flange.
2) GPS puck = mount on glareshield - I have four GPS pucks mounted on my glairshield and have had no issues. Simple and short wire runs.
3) Transponder = On the belly, just aft of the firewall, on the right side, just inboard of the fuel vent. (same as you)
I have a SkyView setup so I have the Transponder antenna and one ADS-B antenna, which is identical to the transponder antenna
4) ADSB = On the belly, just inboard of the left fuel vent. (same as you)
5) ADSB in Strautux = see above.
6) ELT = I have a tip-up and mounted it just behind the roll bar with the antenna held in place with an adel clamp that secures the top end of it to the roll bar and keeps it from moving around.

All of the above works great, including the ELT, which I had activated and didn't notice until I got "the call".

With the above locations, all of your cable runs are short and easy to do with none of them going through the limited holes in the spar.
 
I wouldn't be too concerned with mounting any of the GPS antennas, black pucks or glossy white OMG official exterior ones under the cowl on a firewall shelf. Including those with built-in GPS receivers like the mentioned Stratux compatible Vk-162 remote USB or the UAvionix SkyFX-EXT. Lots of experience out there and more time being logged every day. Plus the Vk-162 is only $12 so why not give it a whirl on the firewall.
 
Bill,

Can you clarify where you mounted the Stratux box?

I don't have a Stratus system as I'm running a SkyView with their integrated ADS-B.

I did mount the Dynon ADS-B box on the side of the left panel support rib. To mount the SkyView backup battery, I formed some aluminum into a "hat" section "_|--|_" that would fit over the ADS-B box and attach with the same screws, added some plate nuts to the underside of it, and screwed the battery box to the top of it.

Does that make sense?

I could have mounted other things to that hat section but I did it as a retrofit and only had to find a place to mount the battery box.

If you are going to go with that white receiver, I would just mount it on the glair shield and cover it with black cloth so it doesn't reflect on the windscreen.
 
Last edited:
I wouldn't be too concerned with mounting any of the GPS antennas, black pucks or glossy white OMG official exterior ones under the cowl on a firewall shelf. Including those with built-in GPS receivers like the mentioned Stratux compatible Vk-162 remote USB or the UAvionix SkyFX-EXT. Lots of experience out there and more time being logged every day. Plus the Vk-162 is only $12 so why not give it a whirl on the firewall.

I do like the idea of the external VK162. I have a fair amount of experience with remote GPS on my RC helicopters....But.....I would need to learn and read up on the mod needed to disable/remove the GPS in the Stratux. If you have a link to read up on that I would appreciate it.

I am absolutely fine with 2 GPS pucks on the glare shield. It is the actual Stratux white box up there I am not real excited about. Which is why the VK162 does intriuge me.

I also am considering putting the Stratux vertically behind the roll bar but on a bracket so it fits against the plexiglass....

Thanks you
 
Bill

Yes, Thank you,

I don't have a Stratus system as I'm running a SkyView with their integrated ADS-B.

I did mount the Dynon ADS-B box on the side of the left panel support rib. To mount the SkyView backup battery, I formed some aluminum into a "hat" section "_|--|_" that would fit over the ADS-B box and attach with the same screws, added some plate nuts to the underside of it, and screwed the battery box to the top of it.

Does that make sense?

I could have mounted other things to that hat section but I did it as a retrofit and only had to find a place to mount the battery box.

If you are going to go with that white receiver, I would just mount it on the glair shield and cover it with black cloth so it doesn't reflect on the windscreen.
 
Charlie,

Take a look at your Stratux. There are 4 or 6 screws holding the box together. Remove them and have a look under the hood. The GPS/USB thingy should be intuitively obvious. Just pull the GPS module out of the USB hub and then insert the Vk-162's USB plug right back in the same USB slot. It takes more time describing it than doing it. It would be analogous to going to your computer and unplugging a USB key chain drive and then plugging in a USB printer cable in its place. There is a small pass through hole in the white Stratux housing for the GPS cable to exit. Woola.

You will see in that same Stratux USB hub two radio receiver modules, for each frequency. They each have a RG 316 coax pigtail coming from them for the antenna connectors. There is also an AHRS module for attitude in one of the USB ports. It's all a very modular design.
 
Last edited:
I don't actually have it yet...I'm on holding out for a Sun-N-Fun break in cost for the Echo, skyfyx and Stratux but....Yes, I absolutely will do that and thanks a ton for the tips!!!

Charlie

Charlie,

Take a look at your Stratux. There are 4 or 6 screws holding the box together. Remove them and have a look under the hood. The GPS/USB thingy should be intuitively obvious. Just pull the GPS module out of the USB hub and then insert the Vk-162's USB plug right back in the same USB slot. It takes more time describing it than doing it. It would be analogous to going to your computer and unplugging a USB key chain drive and then plugging in a USB printer cable in its place. There is a small pass through hole in the white Stratux housing for the GPS cable to exit. Woola.

You will see in that same Stratux USB hub two radio receiver modules, for each frequency. They each have a RG 316 coax pigtail coming from them for the antenna connectors. It's all a very modular design.
 
Back
Top