> > Questions: How long is your antenna? Standard, straight antenna? > Exactly where did you choose to place your belly antenna? I'd also > second Artie's question about where you'd choose to place your > transponder antenna.
Hi Artie & Ed. The antenna is a very simple arrangement in the 1/4 wave variety we use. usually you can cut and end feed an antenna at 1/4 of the wavelength your using and get good results. The lower the frequency, the longer the antenna. I normally cut my antenna length to the freq I use the most. There is some simple math applied here. Take a calculator and use the magic number 234, now divide it by the frequency you use most like 123.05. The result is a length in feet. Then multiply that by 12 and you will have the most desireable lenght in inches. (22.8 inches in this case) Now measure from the skin of your plane to the tip and see how close it is. Most pilots have leaky coax running to their antennas, corroded connections where the wire attaches and where it mounts (it HAS to be grounded to good clean aluminum) and it KILLS the performance of their radio. With a fresh antenna, fresh coax leading to the antenna and a good grounded mount I regularly can talk to FBO's over 75 miles away with any altitude over 2000 above the average terrain and a sportys handheld. Even with a rearward leaning top mounted antenna the power of a panel mounted unit should easily do that good or better. EVERY LAST ANTENNA that I have replaced on any plane that is 15 or more years old had a totally unacceptable ground, connector and time worn coax leading to it. My close friend did not like it too much that I could contact an airport we frequent 10 miles before he could hear it. We replaced his antenna and coax and now I cannot compete with his panel radio. (ended up doing 11 planes in the next 2 weeks on my field) The bottom line was it took so many years to slowly fade away people assumed that was a normal range and went about their business. Radios sound scratchy, muffled and just plain wierd when the antenna does not match the frequency anymore due to corrosion, ground loss or leaky coax cable. If your intercom sounds different while your keyed chances are there is usually already a bad problem present. If people say your hard to understand chances are....etc etc etc. In another email I recieved someone asked if the new fiberglass antennas were better. Well (chuckle) thats a 1/4 wave antenna 'encased' in fiberglass and there is NO performance difference. It looks prettier and wont "blow" back in flight... but then again it's already leaning back (grin) so..... There might be a tube in it. a solid rod, a piece of this wire etc etc. Bottom line is a 1/4 wave is a 1/4 wave PERIOD. A 1/4 wave aircraft antenna has a more than broad bandwidth to cover most any frequency we use regardless of claims. Myself I use a steel antenna on the belly just forward of the tailcone and I can copy the 2 watt atis/awos at another airport 14 miles away no problem. Just how far does one need to talk on the ground anyway. About 1/2 way down I bent mine back at about a 45deg angle to give me a bit more runway/rotate clearance and if it occasionally hits no big deal... It's very flexable and cant be impact damaged. I mounted my transponder antenna on the belly pan between the wings. It was easy to get to the wire and mount by lifting the seat and I mounted as close to the right wing as I could to keep the water from standing on it when its wet. The water runs to the center and leaves my mount Hi and Dry! DO NOT let the antenna become oil soaked. Oil IS conductive and when it's wet from the steel to the belly it lets the signal run through the oil, right down the antenna base, straight to the plane (short) rather than radiate it. It also makes the antenna appear to be longer to the radio and this gives a bad antenna match causing all the wierd things I described earlier besides affecting your recieve range. This goes for ALL antennas, if they are wet with anything even if only a recieve antenna the performance is affected. The cheapest radio in the world with a good antenna will kick a high dollar rig and an old or corroded antennas butt. I have a WilTron antenna analyzer that I will bring to the EOC convention in july. It checks the loss in the wire, the mount, the antenna, the freq it's tuned to and it's "match" for what your using it for in general and if anyones interested we'll play around with your antennas a bit. And yes harry, I moved (grin) Claude Wheelbarger Bridgewater, VA. (SHD) 93620 __________________________________________________________________________ ______ To unsubscribe from this list please send mailto:[EMAIL PROTECTED] _____________________________________________________________ Who will win the Oscars? Spout off on our Entertainment list! http://www.topica.com/lists/showbiztalk
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