Author Topic: Antenna Installations  (Read 3700 times)

Bill Poynter

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Antenna Installations
« on: January 11, 2012, 11:10:42 AM »
I believe it would be useful to discuss the type of VHF antenna we are using and how it performs relative to where it's located on the airframe.  Because of the fact that I earn my living in the two-way radio industry, I'm pretty attuned to how my aircraft radio is performing. 

For esthetic reasons, I think that most people would prefer to not have an antenna mounted on the outside of their vintage aircraft.  The antenna that was installed on my plane when I purchased it was located inside the fuselage, behind the baggage compartment.  It worked fairly well, unless I was flying directly toward the station I was communicating with.  In those instances, the range was very limited; 2-3 miles.  That made it pretty difficult to enter class D airspace without hacking off the tower personnel.  That antenna was a straight whip mounted on an aluminum ground plane in the floor of the fuselage.

I'm interested in learning what other Cadet owners have experienced with their setup. 

I'll be glad to share the results of my other antenna configuration experiments.  I've finally settled on one that seems to work quite well.

Woody

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Re: Antenna Installations
« Reply #1 on: January 11, 2012, 12:32:11 PM »
You beat me to this post Bill.  I've been looking at units that you bury in the tail or down the wing spar.  I have not talked to anyone that has them but the tail is out for me as it is sealed and I don't want to open it for an antenna.
My question  is do they work as well as the external units which I had rather not have because of drag as well as the plane being antique.

Scott Crosby

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Re: Antenna Installations
« Reply #2 on: January 11, 2012, 12:46:30 PM »
My project has what appears to be aluminum screen draped across the top underside of the fuselage for a ground plane and a hole in the top plywood skin where a bent whip antennae likely went. I need to do something different than this, too.

Bill Poynter

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Re: Antenna Installations
« Reply #3 on: January 11, 2012, 03:06:21 PM »
After I became dissatisfied with the antenna installed inside of the fuselage, I decided that if I were going to place an antenna on the outside, I would try to make it inconspicuous.  I installed a bent whip on the bottom, in the middle of the aluminum panel below the floorboards.  This location worked just so-so when flying, and performed very poorly on the ground. 

I felt that if I had to place an antenna on top, it had to look correct for the vintage of the aircraft.  To me that means a straight, rod/whip type of antenna.  I decided that the steel frame of the windshield/doors area might make an adequate ground plane for the antenna.  I installed the straight whip type antenna in the rear/starboard quadrant of the junction in that frame.  Itís just behind the windshield bow.  You can see this antenna in the big photo on the Culver Cadet website.  This setup works great.   The range is excellent.  It actually resembles the antennas Iíve seen in photos of PQ-8ís.  Iíll be happy to send photos of the mounting details, if anyone is interested.
« Last Edit: January 16, 2012, 03:56:43 PM by Bill Poynter »

Paul Rule

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Re: Antenna Installations
« Reply #4 on: January 18, 2012, 01:20:39 PM »
Looking on the Spruce website at the MicronAir M760 com radio,  the manuals available to download have a useful section on antennas for wood aircraft.

Woody

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Re: Antenna Installations
« Reply #5 on: January 18, 2012, 03:33:33 PM »
Does anyone have any info on antenna's from Advanced Aircraft Electronics?  I don't know how they would guarantee the antenna once it is sealed in the wing if it did not work.  Sure sounds good but is $150 for a pig in a poke.  I have not talked with them about their products.

Bill Poynter

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Re: Antenna Installations
« Reply #6 on: January 18, 2012, 04:58:25 PM »
In my opinion, the placement of a VHF antenna in the wing will not produce very good results.  The reason is that VHF ground stations are designed to transmit and receive a vertically polarized signal.  To obtain good performance, the antenna on the aircraft should be oriented in the same (vertical) plane as the ground station antenna.  The antenna you mentioned does not require a ground-plane, however its 43Ē length is twice as long as a ground-plane type antenna.  The length of any VHF antenna precludes mounting it vertically in the wing.  The fuselage is about the only place that this antenna will fit vertically.  Mounting it inside the fuselage produces its own set of problems though.   When I mounted the whip on the cocpit frame, I left my internal fuselage antenna in place so that I could use it for a backup handheld radio.  Thereís a pretty good FAQ on the companyís website.    http://www.advancedaircraft.com/FAQs/faqs.htm#diagram 

Bill Poynter

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Re: Antenna Installations
« Reply #7 on: June 10, 2012, 05:09:43 PM »
Here's a link to a pretty good aircraft antenna article on the XCOM website:

http://www.xcom-usa.com/education/XCOM-Aerial-Dummies-Guide.pdf