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RST Engineering wrote:
> "Phil" <pdl@imaginenet.net> wrote in message
> news:dtg7qt01qdr@enews2.newsguy.com...
> > Hello
> > A young friend of mine is in the process of restoring an EAA Biplane ,
> > last weekend we started working on his new engine mount , he started to
> > discuss the fact that he is installing his VHF Com. antenna inside the
> > fuselage , this experimental is the older tube and fabric design , cockpit
> > is about 24 in. wide and narrows to the tailpost , being an old HAM radio
> > operator , a lot of red flags went up , he want's to mount a standard 1/4
> > wave vertical somewhere aft of the cockpit area , width in the proposed
> > spot would be about 14 in. , all of my experience with radiating elements
> > says that it will not work , I think the element will try to couple with
> > the tube structure , SWR will go sky high and it will be a no go , I'll
> > bring an MFJ 259 to the airport next weekend and try to give him a graphic
> > demo. of my perceived doubts.
>
> Your 259 may or may not show the actual problem. The actual problem is that
> the steel tube fuselage is an excellent Faraday shield and almost all of the
> radiation will wind up warming the steel tubing. We've tried it and tried
> it every way from Sunday and it just will NOT work.
>
>
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>
>
> > I know that the guys with the glass and wood are doing OK with there
> > internal Ants. , wondering if someone else has had any luck with getting
> > RF to exit a 4130 airframe , he wants it to use in the standard 118- 136
> > portion on the band , plane has an alum. turtledeck , I told him that the
> > deck should make a good gnd. plane for the 1/4 wave vert. , he is
> > concerned about aesthetics , any thoughts would be appreciated .
>
> The steel tubing will make a better groundplane unless the turtledeck is
> electrically fastened to the tubing. Again I say unto you, getting RF out
> of a steel tube fuselage is an exercise in futility.
>
> Jim
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Re: VHF Com. Ant. for Biplane
