Ive doubted some of the claims about fresh water swamps based only on personal experience. At a prior QTH I had them on 2 sides and extending to a mile or more and the 160 vertical "appeared" to play better then expected. All that rotting vegetation had to be good for something and it rarely froze more than a few inches in the winter.
Carl KM1H ----- Original Message ----- From: "Guy Olinger K2AV" <[email protected]> To: <[email protected]> Cc: <[email protected]> Sent: Friday, September 23, 2011 5:37 PM Subject: Re: Topband: Effect of current max not at base of vertical. > Apologize for earlier half-done post. Spastic hit on send key. > > See http://www.fybush.com/sites/2005/site-051028.html for a Franklin and a > nice article. > > For 1530 kHz, that's a *pair* of two vertical halfwaves in phase. 50 kW > gives 3545.89 mV/m for broadcasting purposes. Note the relative lack of > neighbors, and therefore lack of 24 hour miscellaneous diodic signal > demodulation, talking window screens, permanently lit florescent bulbs, > etc. > > Note that this monster is not too far from 160m. Think big and put an > only > slightly downsized 160 version out in the salt shallows somewhere on the > western side of Cheasapeake Bay. Without any controversy whatsoever as to > ground induction losses (zero) EZNEC says this would put 13.6 dbi gain > toward Europe at 3.1 degree takeoff. Order of magnitude: three element > yagi. > > Just for comparison, if I drain Chesapeake Bay and fill it with concrete > rubble and other urban debris (can do magical things in EZNEC) I get 5.0 > dbi > at 12.9 degrees. The full EZNEC preloaded table follows, filling > Chesapeake > Bay with other dirt, or turning it into a fresh water lake. These figures > are *without* any ground field copper underneath, as it is not needed for > a > current sink and I have no data on what kind of field might actually be > employed. > > Urban debris: 5.0 @ 12.9d (-5.0 dB from that angle takeoff over > seawater) > Sandy 4.8 @ 10.7d (-6.6) > Rocky, poor 5.2 @ 10.6d (-6.2) > Average 5.4 @ 9.0d (-6.8) > Forest 5.7 @ 8.7d (-6.6) > Marshy 6.1 @ 8.4d (-6.0) > Rich pastoral 6.8 @ 8.1d (-5.8) > Very rich 9.1 @ 7.1d (-3.8) > Fresh water 8.4 @ 8.9d (-3.8) > Salt water 13.6 @ 3.1d (0) > > One can dream. 73, Guy. > > On Fri, Sep 23, 2011 at 1:21 AM, Herb Schoenbohm <[email protected]> > wrote: > >> George, Are you familiar with the Franklyn antenna design? >> Some broadcasters swear by them and claim a 3 db increase over a 1/4 >> vertical radiator. >> >> Herb, KV4FZ >> >> > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1410 / Virus Database: 1520/3916 - Release Date: 09/24/11 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
