Antenna Tips

kevin
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Antenna Tips

Postby kevin » Sun Aug 30, 2015 6:35 am

Some antenna tips. I started with a blade when I rebuilt 45WE because of interference with the GPS when I used the built in antenna. After complaints of poor reception from ATC and range more limited than I am used to, I decided to try the com antenna built into the tail. I added 2 chokes, replaced almost all of the antenna cable with RG400, and removed all of the loops. Now I can transmit and pick up the ATIS from almost 100 miles from 6000 feet. Could easily talk to Jax Center from Tampa's airspace.

http://www.express-builder.com/documents/Antenna%20Tip%201.pdf
http://www.express-builder.com/documents/Antenna%20Tip%202.pdf
http://www.express-builder.com/documents/Antenna%20Tip%203.pdf
http://www.express-builder.com/documents/Antenna%20Tip%204.pdf
http://www.express-builder.com/documents/Antenna%20Tip%205.pdf

LarryK
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Joined: Wed Dec 31, 2014 11:09 pm

Re: Antenna Tips

Postby LarryK » Sun Nov 01, 2015 11:42 am

Did you ever take any pictures of the installations? I don't have the preinstalled antenna in the vertical, and don't thing adding one now would be prudent.. I have picked up 2 advanced electronics antenna's for com and nav, I have a TEDS ADSB antenna from aircraft spruce.. Now the question is where to mount them. I also have a GTN650 and that antenna will go up on top, but keeping away interference from all the others shouldn't be an issue but locations are tricky... any suggestions?

kevin
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Re: Antenna Tips

Postby kevin » Wed Nov 25, 2015 7:21 am

The manual section 6 has the antenna info. Its not critical where it is, here is what you need to know:
Coms are vertically polarized meaning the antenna sticks up. Navs are horizontally polarized meaning they lay flat.
One of my airplanes was started by others, and the antenna in the tail didn't work. Probably a bad solder joint. Here is what I recommend. The average frequency of our coms is 125 mhz. The ideal antenna length at 1/2 wave for this frequency is 3' 9". Go to Lowes or Home Depot in the masonry department. Look for copper flashing. Doesn't have to be thick, just normal copper flashing. Cut this into 2 strips 1 inch wide and 23 inches long. Take your RG58 or RG 400, trim off about 2 inches of the outer insulation and separate the inner shielding from the center conductor. Solder the shielding to one piece of copper, and the core to the other. Glass these into the SIDE of the fuse toward the aft, as vertical as you can make it and in a V shape about 60 to 80 degrees apart. I just put 1 4" piece of glass tape over the foils to keep them in place. Works well.
Make the same for your navs, just glass it into the bottom of the fuse to make it horizontal.

The localizer uses the Nav, the GS is on a different frequency, average 332 mhz. Cut 2 more foils about an inch wide again, but this time 9 inches long. Solder another piece of RG400, glass it at 60 degrees into the bottom and connect it to the GS antenna of your radio. Mine works from 20 miles out.

If you have marker beacon, its a little different. Make it from 2 foil strips 19" each, but glass these in lined up from front to back in a straight line not a V, I put mine beside the cable tunnel under the back seat. It has to be this way because the MB antennas are directional straight up and very low power so that you have to be directly over it to get it.

KA

LarryK
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Joined: Wed Dec 31, 2014 11:09 pm

Re: Antenna Tips

Postby LarryK » Sat Nov 28, 2015 2:23 pm

Great tips. I will try this and see how they work out... And these are mounted inside guessing, or outside of the fuse?

kevin
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Re: Antenna Tips

Postby kevin » Thu Jan 14, 2016 6:24 pm

All of the antennas are mounted inside the fuse. I will try to remember to take a pic tomorrow when I get to the airport. As an avionics tech and a Ham radio operator we build our own antennas all the time. Its not hard to do.

The length of the conductors is based on frequency and a little based on the angle of the V that it forms. If you need more let me know, and send me an email too in case I am out and cant check the forum.

KA

LarryK
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Joined: Wed Dec 31, 2014 11:09 pm

Re: Antenna Tips

Postby LarryK » Wed Mar 30, 2016 5:39 pm

Any pictures of the antennas and their locations? Things are starting to close up for me. do you have to have the Transponder antenna mounted on an outside surface?

kevin
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Re: Antenna Tips

Postby kevin » Sat Apr 16, 2016 9:42 pm

The transponder antenna must be mounted outside with some shielding between you and it. It operates on 1090 mhz, which is in the microwave band.
Mine is in the center of the fuse directly underneath the box behind the firewall. This keeps the transponder antenna lead short for lower losses. I have an 8" square piece of aluminum that the antenna is mounted through that acts as a ground plane and a shield.
Even with this, I get a little bit of clicking through my headset from the transponder. Not bad, but its there. Our composite airplanes do not block any RF radiation, so I had to deal with interference from the radios to my AHRS and a few other issues.

LarryK
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Joined: Wed Dec 31, 2014 11:09 pm

Re: Antenna Tips

Postby LarryK » Tue May 17, 2016 10:29 pm

I bought the Advanced Aircraft Electronics Transponder version. 6" long. Haven't figured out a good mounting location yet but. wished I had installed on in the wing box before I bolted in the wings. My other thought is below the Flap actuator. Where did you put your Static port?

kevin
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Re: Antenna Tips

Postby kevin » Fri Jul 29, 2016 8:36 pm

On one plane I have the Piper pitot/static port combo. It reads low indicated but the pitot is on the front of it and the static is on the back. On the other plane I installed static ports behind the baggage door that I put in - essentially about 12" behind the bulkhead one on each side and tied together.

This is the arrangement that I see most often on certified aircraft except for Pipers with the combo unit.

KA


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