Re: [COUPERS] radio antina

[Claude Wheelbarger]

Hi Ken  Well it's not a difficult theory. The waves ideally travel straight out 90 deg from the antenna. So ideally if the antenna is vertical it will radiate straight out in all directions. However... since the feedpoint of the antenna (where the coax attaches) is at the base it will give a slight 7-10deg up angle of radiation creating a shallow bowl when pictured from the side. If the antenna is sloped back at say a 45deg angle then the signal will go way high in front of you and hit the ground behind you. The antennas weakest signal is towards it's own base and in the case of a sloped antenna that places your destination field in your weakest coverage area. Since there is very little drag difference between the two I'd opt for the vertical. Those who have seen my coupe have seen my antenna mounted on the bottom of my plane just forward of the tailcone. This gives me a slight down angle of radiation for 360deg coverage and since it blows rearward slightly it makes it ideal for talking to airports in my flight path. Last may I had an antenna on top of the coupe just aft of the canopy and the identical antenna on the belly at the rear. At 40 miles out heading directly towards my home field they copied the top antenna at S3 and the belly at S7-8 with a scale of 1-9 on the radios recieve meter. This relates to roughly twice the forward signal strength and in theory twice the range. I was able to talk to Steve Kish from PA in his mellow yellow coupe at 70+ miles plane to plane with the belly antenna on the way back from nationals last year no problem and all I have ever used was a Sportys JD-200 handheld with a headset and the external antenna. Since I am an RF wireless communications engineer I couldn't help but play with all the ideas <G>  Hope this helps Ken!   Claude Wheelbarger Bridgewater, VA. (SHD) 93620 ----- Original Message ----- From: Ken Carnahan To: ERCOUPE Sent: Monday, February 21, 2000 10:09 PM Subject: [COUPERS] radio antina Witch is better for to use with com radio stright or bent antina ? thanks   Ken  Mo.