Date: Wed, 16 Feb 94 04:30:11 PST From: Ham-Ant Mailing List and Newsgroup Errors-To: Ham-Ant-Errors@UCSD.Edu Reply-To: Ham-Ant@UCSD.Edu Precedence: Bulk Subject: Ham-Ant Digest V94 #35 To: Ham-Ant Ham-Ant Digest Wed, 16 Feb 94 Volume 94 : Issue 35 Today's Topics: Antenna size vs frequecy? Belden 8214. Wat is it? Help - MacMininec antenna modelling R7 vertcal antenna for trade... Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Ant Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-ant". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: 14 Feb 94 19:25:54 GMT From: yuma!galen@purdue.edu Subject: Antenna size vs frequecy? To: ham-ant@ucsd.edu In article <1994Feb14.152504.27926@ncsu.edu> Shane Trent writes: >Hello, Hi yourself. >I read years ago that the optimum length of an antenna is 1/2 wavelength >of the frequency being received, this article was talking about >commercial FM. Is this true (no equations needed)? For the infamous 1/4 wave dipole, yes (2-1/4 wave halves). There are better antennas, but they aren't as simple. >Also, would this apply to a dish antenna? What size microwave (900 MHz) >should be used? >Thanks for your help, >-shane A dish is simply the reflector, the antenna is actually at the feed point. There are many ways to get a signal from a dish, like the 1/4 wave dipole, a resonant cavity, crossed dipoles... It depends on what kind of signal you're trying to get, like if it's linear or circular polarization, if you want to demodulate it or if you're just interested in the strength... The dish size is what determines the gain, bigger dish=more gain. If the dish is not solid, the size of the holes limits the upper freq the dish will reflect, I think the cutoff is around 0.1 the wavelength. Try the ARRL antenna book, or the RSGB VHF/UHF handbook, or 'Tools of Radio Astronomy' by Kristen Rolfs. Good reading for antenna folks. Galen, KF0YJ ------------------------------ Date: Mon, 14 Feb 1994 14:33:14 GMT From: agate!library.ucla.edu!csulb.edu!csus.edu!netcom.com!henrys@ames.arpa Subject: Belden 8214. Wat is it? To: ham-ant@ucsd.edu I have some Belden 8214 Coax at the house. Does anybody know what the characteristics are? Is it 50 Ohm? Thanks, Smitty, NA5K -- ----------------------------------------------------------------------- | Henry B. Smith - NA5K henrys@netcom.com | | Dallas, Texas | | | | "I'm not sure I understand everything that I know" | ----------------------------------------------------------------------- ------------------------------ Date: Mon, 14 Feb 1994 16:18:41 GMT From: swrinde!cs.utexas.edu!howland.reston.ans.net!EU.net!uknet!pipex!bbc!ant!boyer@network.ucsd.edu Subject: Help - MacMininec antenna modelling To: ham-ant@ucsd.edu Russ Renaud (ae517@FreeNet.Carleton.CA) wrote: : Can anyone offer any advice on how to model an inverted-vee antenna using : either MacMininec or Mininec for dos machines? : MacMininec offers several examples for straight dipoles, a trap antenna, : as well as a yagi, but I have had little luck in getting it to model an : antenna which is not straight. : Yes, I know, I shouldn't be so cheap and buy Elnec :-) : any help would be greatly appreciated. : de VA3RR/AA8LU : -- I haven't used mininec, but I use NEC on a regular basis. The way I would modle a vee is to make a really short wire of say 1segment the drive point & then connect the two sloping sides to this. NEC is avail via ftp from netcom.com in the pub/rander/NEC directory. Have fun John B john.boyer@rd.eng.bbc.co.uk ------------------------------ Date: 14 Feb 1994 16:17:07 GMT From: pa.dec.com!src.dec.com!src.dec.com!estrella@decwrl.dec.com Subject: R7 vertcal antenna for trade... To: ham-ant@ucsd.edu ********************************************************* Posting for my brother who doesn't have an account... I have a cushcraft R7 vertical antenna I want to trade for a good working HF solid state transceiver; I can make up some cash with the antenna if necesary. I can be reached at ( 408 ) 279-6028 evenings and weekends. Luis Estrella KD6VTZ !!! TRADE ONLY !!! ********************************************************** Or you can send me e-mail and I will give Luis your message. John Estrella ------------------------------ End of Ham-Ant Digest V94 #35 ****************************** ******************************