Interfering and/or desensing the receiver is a valid concern. I would "enable" the 900 MHz transmitter with one of the receiver channels so that I had to have a predetermined pulse width to keep it on. If you could drop the transmit power to 100 mw or less I doubt you would notice the signal strength drop in normal RC conditions. you will lose most of the signal when the end of the antenna is toward your receiver. John Ferrell W8CCW "Life is easier if you learn to plow around the stumps" http://DixieNC.US ----- Original Message ----- From: "Zik Saleeba" To: "Microcontroller discussion list - Public." Sent: Thursday, June 21, 2007 8:55 PM Subject: Re: [EE] Feeding a dipole > Thanks John (and everyone else who responded). Thanks for the info on > your dipole simulation - I might give it a try in one of the NECs. I'm > using FHSS on the 902MHz-928MHz ISM band so the antenna shouldn't be > too narrow band. Still, even at the edges of the band the level of > loss you describe is probably fine. > > At this stage I'm a a bit more worried about radiating lots of RF down > the coax shield into my 36MHz R/C receiver and also possibly > interfering with my sensors - which include a sensitive barometric > pressure sensor, accelerometer and gyros. I'm thinking a simple sleeve > balun or transmission line balun might help here. I'm unclear on > whether it's going to be necessary though - maybe the interference > won't be an issue at all. Maybe I'll just take it out for a fly and > see if I lose control during transmissions. That always makes life > exciting. > > Cheers, > Zik > > On 6/22/07, John Ferrell wrote: >> I modeled (EZNEC4+) a dipole using 6.1 inches (over all) of #20 wire. >> SWR computed 1.62 to 1.43 over 890 to 910 mhz. >> >> My conclusion: do not worry about swr or balancing the feed. Do not worry >> about copper foil, #20 wire under any tape will work fine. >> >> IF this is a Radio Control model the telemetering transmitter is way more >> powerful than most RC transmitters. >> >> A demo copy of EZNEC will do all the dipole modeling you need. >> >> John Ferrell W8CCW >> "Life is easier if you learn to plow >> around the stumps" >> http://DixieNC.US >> >> ----- Original Message ----- >> From: "Zik Saleeba" >> To: "Microcontroller discussion list - Public." >> Sent: Wednesday, June 20, 2007 7:49 PM >> Subject: [EE] Feeding a dipole >> >> >> >I have an RF question which has been bothering me for a while. I have >> > a 900MHz 1W transceiver module which I'm planning to put in a model >> > plane for telemetry purposes. Every gram counts so rather than using >> > an off-the-shelf antenna I'm planning to make a dipole from conductive >> > foil tape stuck to the wing. I have a small amount of experience with >> > VSWR meters so I think I can get that part of the system working >> > pretty well. >> > >> >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist