Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!sdd.hp.com!hplabs!hpfcso!hpfcdj!myers From: myers@hpfcdj.HP.COM (Bob Myers) Newsgroups: sci.electronics Subject: Re: Amplification of an RF signal from an antenna Message-ID: <17660133@hpfcdj.HP.COM> Date: 16 Dec 90 00:01:11 GMT References: Organization: Hewlett Packard -- Fort Collins, CO Lines: 29 > I am attempting to build an amplifier for my FM antenna to improve >reception. Does anyone out there in netland know the maximum peak to >peak voltage and current that I can put into my antenna port? Also, any >suggestions on implementation? I am considering a push-pull amplifier. >Thanks. There's no need for a "push-pull" amplifier; even if you were to build an RF push-pull, it would have no voltage gain (being essentially two common- collector amps back to back). What you want is an amp with good voltage gain and a wide bandwidth, and which can match to both the antenna and the receiver's antenna input. (By the way, there's no need to worry about both the maximum voltage and current; the impedance of the antenna input is fixed, so nail either of these down, and you've got the other.) A common-base stage, possible followed by a common-collector for impedance matching (although there would be other ways to do this), sounds like the ticket here. (Common *emitter* stages aren't usually used for RF amplifiers, as the Miller effect capacitance of this configuration limits the bandwidth over what could be acheived with the same device in the CB configuration.) So that we don't get into too much detail here, may I suggest getting a copy of the latest ARRL Radio Amateur's Handbook? It will describe a number of suitable amplifiers and the theory behind them. (Note that anything the ARRL describes for use in the amateur 2-meter band should be easily adaptable to broadcast FM.) Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not Ft. Collins, Colorado | those of my employer or any other myers@fc.hp.com | sentient life-form on this planet.