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This appears to be a slight variation on a simple dipole antenna, which works well in wooden and fiberglass airplanes. They are cheap to make, about 2 or 3 dollars for materials. For optimum performance in com usage, the antenna should be oriented as near vertical as possible since uhf com signals are vertically polarized. I have used two (that I made myself) in my Maranda (wood and fabric) for years with excellent results. Jim Weir used to have a booklet that gave easy-to-follow instructions on making dipole antennas for com, VOR, FM, etc; but, you can probably find the same info on the web. Weir does not recommend them for installation inside metal-framed or aluminum-skinned structures. For that reason I am using exterior 1/4 wave antennas for my 4-place.
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Thanks for sharing your experiences guys. AAE says they work well inside a rag and tube fuselage and the few pireps I was able to find seemed to back that. Google revealed Jim's antenna manual which I found very interesting. I might have to order his kit and try making an antenna.Scratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.
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Will all of your antenna installations result in all antennas being installed internally?....leaving no external antenna's that produce drag, exposure to damage, and exposure to injury?
Is this the manual that you referenced? XCOM Aerial Dummies Guide.pdfBrooks Cone
Southeast Michigan
Patrol #303, Kit build
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My technical knowledge of antenna function is nil. I'll offer a touch of anecdotal experience, however. I had internal (store bought) 'foil type' NAV & COMM antennas in my Glasair. They worked alright. Within 15 or 20 miles of a station, communications were fine. Much further than that wasn't great. I could hear them, but not always the other way around. This kept me very aware of situational awareness when approaching controlled airspace, covering 4 SM per minute. Like I said, they worked alright, not great. On the Patrol, external Comant antennas work great.
Please keep us informed as to the performance of these internal antennas in Bearhawks!
Bill
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Brooks, all of the potential installations will have the antenna inside.
Here is a link to the manual: http://www.rst-engr.com/rst/products...20Manual-s.pdf
Bill, thanks for sharing your experience. The performance you experienced isn't what I'd hope for. Of the few reports I found about the AAE antenna installed in tube fuselages only one mentioned range. His range was 60miles which isn't great but totally acceptable.Scratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.
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I found this paragraph in the report interesting. Not sure what "tricks we are about to develop" means.
Tube and fabric folks -- please understand this basic principle: A cagework of steel tubes is every bit as good a radio shield as a solid-skinned airplane. You CANNOT put an antenna inside
of a metal-tube structure and expect even mediocre performance. You MUST use the tricks that we are about to develop for metal planes even though to the eye your airplane is 90% fabric.
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Originally posted by Ivan View PostI found this paragraph in the report interesting. Not sure what "tricks we are about to develop" means.
Tube and fabric folks -- please understand this basic principle: A cagework of steel tubes is every bit as good a radio shield as a solid-skinned airplane. You CANNOT put an antenna inside
of a metal-tube structure and expect even mediocre performance. You MUST use the tricks that we are about to develop for metal planes even though to the eye your airplane is 90% fabric.
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I skimmed thru the Antenna Document. My goal with this post is to seek seek knowledge and wisdom in a non-judgmental way. Please forgive me if I fail at this.
The fifth paragraph on p.11 says we don't want a 12" piece of metal within 24 inches from an antenna. Here is some additional information I found about COM antennas on p.35 (which immediately follows Ivan's quote.)
1. COM antennas can be hidden in any vertical area where a 22†piece of wire or tape can be bent around as nearly vertical as possible. Remember, though, that the more metal you get near the TIP of the antenna the less it will act as an antenna. Some places clever designers have hidden the antenna have been in the dorsal fin fairing and in “droopy†wingtip plastic housings. In a droopy wingtip, put the tip of the antenna as nearly vertical to the earth’s surface as you can get it.
I cant see an antenna being installed inside a Patrol fuselage complying with the document. I rather visualize the antenna being installed in the leading edge of the vertical stab somehow....maybe balsa leading edge?If I am wrong, help me understand. A little extra work to have excellent internal antenna installations is intriguing to me.
Brooks Cone
Southeast Michigan
Patrol #303, Kit build
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Yeah, Brooks. I was having the same concern. I can't figure any place in the Patrol fuselage to put that antenna without one or both ends being within 24 inches of a 12+ inch piece of tubing. Even the leading edge of the vertical stabilizer would be right next to the leading edge tubing... I'll probably just go with standard antenna on the wing and/or belly. But I've also got plenty of time for you guys to experiment, and tell me if the "buried" antennas work or not, so I can change my mind! LOLJim Parker
Farmersville, TX (NE of Dallas)
RANS S-6ES (E-LSA) with Rotax 912ULS (100 HP)
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You guy are right, according to Mr. Weir an internal antenna on a BH won't perform well. AAE says they will, but they are trying to sell them. The Stearman restoration group seems to be satisfied with them. A couple Piper guys reported good results. So they obviously do work but how well we don't know. I'm sure it is far from ideal but how much range do we really need? I think this will be a fun, low cost, low impact experiment. If it doesn't work out I'll put a whip on top the wing as originally planned. If I had come across this info earlier I would have put an antenna in the V-stab like one of the piper guys did.Scratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.
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