Path: utzoo!mnetor!uunet!husc6!mailrus!ames!pasteur!ucbvax!hplabs!sdcrdcf!trwrb!trwind!johng From: johng@trwind.UUCP (John Greene) Newsgroups: sci.electronics Subject: Re: Radio booster Message-ID: <392@trwind.UUCP> Date: 6 May 88 16:06:37 GMT References: <845@imagine.PAWL.RPI.EDU> Reply-To: johng@trwind.UUCP (John Greene) Organization: TRW Information Networks Div Lines: 34 In article <845@imagine.PAWL.RPI.EDU> snyderw@pawl22.pawl.rpi.edu (Wilson P. Snyder II) writes: > > I am a member of a club which uses Radio Shack headset walkie-talkies. >We are having a problem with the range of these units, so I replaced the >antenna with a longer, common wire which runs through several rooms. Now, >the problem is that this decreased the antenna gain, so now I need to boost >the power output of the radio. I assume that the radio was at the 100mw >FCC limit (47 MHz), but since the antenna is now less eficient, boosting >should be possible. > So, what I am interested in is a small 9Vdc circut to boost the >radiated antenna power. Thanks. > > If the antenna is less efficient now than it was before, why change it??? I think your problem is not a less efficient antenna, but a terrible impedance mismatch you introduced with the long wire. The radio is designed to have maximum gain using a 50 ohm load at the antenna, anything else is going to result in standing waves which means more power dissipated in the radio than radiated to the air. There are several ways to increase the gain of an antenna by it constuction. The easiest to implement would be to make a dipole of the proper length for 47 MHz. This may be all that you need. I don't remember the correction factor for calculating the wavelength in air but I'm sure you can find it in the library or someone on the net may have it handy to post. A properly constructed antenna may be all that you need. -- John E. Greene "People are just like frankfurters....You have to decide if you're going to be a hot dog or just another wiener" DLR TRW Information Networks Division 23800 Hawthorne Blvd, Torrance CA 90505 ARPA: johng@trwind.ind.TRW.COM USENET: ..trwrb!trwind!johng