Antenna position

Any thoughts on the best position for the COM antenna? I'm thinking of placing it inside the fuselage, behind the baggage bay. Any reason why an internal antenna wouldn't work in the Kitfox 3?

Dave,
I'm no RF expert but from what I understand locating the antenna inside the steel cage would seriously compromise both receive and transmit performance. All the later model Kitfoxes have tabs welded to the structure under the cabin area for both transponder and comm antennas. Personally, I'd locate your antennas either on the belly or on the top of the rear fuselage. Hundreds of installations in these areas show they work well.

YMMV,

from my experience with CB's ,..(knowing that the wave length is different between aircraft and Citizen band,).. a ground plane at the base of the antenna works best,.this can be the fuselage , like mentioned ,..the newer models have the tabs welded in place for the antenna's,..the length of the ground plane( fuselage) will be the strongest signal,..side to side the weakest,..to help this so you have a more even signal pattern you can place a very light sheet of aluminum between the fabric and the antenna base,(on the inside of the aircraft) I have used newspaper print press plates,..which are very thin sheets of aluminum. I'm thinking .003...if you want to go one step further ,..on the ground side of your radio power supply,..attach a .05 capacitor from the hot wire to the ground in conjunction with your normal ground,..this will eliminate a good ammount of any static you get from other electrical devices on board. I think the .05 capacitor is 25 cents at radio shack.

placing the antenna inside of the fuselage might reduce some of your recieve capability ..but it will definately reduce your broadcast ability,..
antenna's work off a wave length,..each mode of radio communication has it's own wave length ..hence a 10 meter radio has a 10 meter wave length,..CB radios have a 36 foot wave length ..etc..if the antenna is "caged" let's say installed inside the fuselage ,..when you key the mic ..the RF is bounced back to the antenna ..creating feed back which can fry your radio finals,..once this happens ..only someone who is right next to you will hear your broadcasts,.someone at geater then a couple hundred feet will barely hear you ..and someone at 1/2 a mile ..forget it ..your broadcast won't even be a static bolt..
Scenerio .non-towered field.your 1.5 miles out ,..you hear traffic on the frequency for the airfield your approaching,..the traffic is announcing their intentions "claremont traffic Baron N-000FasterPlane 2 miles out at 2000ASL for straight in on 2-9",..and waits for other traffic to respond before commiting,..you responded ..but he couldn't hear you ..your response was .."claremont traffic Soontobewrecked
N-000RadioFinalsFried ,1 mile out at 1500ASL for straight in on 1-1" your looking for the baron ..he hasn't got a clue that your there,..let's hope he isn't practicing IFR approaches.

There have been several planes that have the COMM antennas in the tail. They work just fine.

I placed two COMM antennas in mine as the picture shows, however I did drop them down a couple ribbs so I could work with the terminals after the tail was covered. This is how Steve Kellander has his and he has no problems sending or receiving.

Attachment 485

Probably best to mount the comm outside the structure. I personally have my comm mounted inside the vertical stabilizer and it works well enough. An option only if you are recovering and adding wood formers to the tail.
Would it work better on the turtle deck or on the belly? Most likely yes. I would pass on mounting inside the fuselage structure. The antenna's you see mounted inside by the baggage area are for the ELT. Not probably as critical as the comm unless of course you have an "incident". I also have my ELT mounted inside along the baggage compartment. Again my comm works OK but I have no quantifiable evidence to say how much the signal is degraded by my antenna's location. So far no complaints from any towers or flying mates. I does make for a nice look with no external antenna's.