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## Re: [TowerTalk] horizontally polarized antennas and salt water

 To: , "Pete Smith" Re: [TowerTalk] horizontally polarized antennas and salt water "Jim Lux" Tue, 18 Jan 2005 11:41:22 -0800
 ```----- Original Message ----- From: "Pete Smith" To: "Jim Lux" ; "Stephen Reichlyn" ; Sent: Tuesday, January 18, 2005 11:00 AM Subject: Re: [TowerTalk] horizontally polarized antennas and salt water > At 11:21 AM 1/18/2005, Jim Lux wrote: > > >Pete Smith wrote: > > > > > > It does, but not a bunch. > > > > > > I quickly modeled a 40m yagi at 104 feet over average ground versus salt > > > water. Forward gain went from 11.86 dBi (avg) at 18 degrees to 12.45 dBi > > > (salt). Takeoff angle, interestingly, went up one degree for the better > > > ground plane. Moving the antenna down 6 feet over salt water moved the > > > takeoff angle up 1 more degree, from 19 to 20 degrees. > > > > > > >Just as an idle question.. I wonder if the gain change is due to a pattern > >shape change (narrower main lobe), or due to a reduction in losses. The > >average gain number would tell you, since it's integrated over all look > >angles. > > It appears to be reduced losses. The average gain over salt water is -0.06 > dB; over average ground it is -0.96 dB, per NEC-2. Very interesting...In fact, the directivity is less with the salt water... The difference in foward gain is about 0.5 dB, but the difference in loss is 0.9 dB, so the "extra" 0.4dB must be going into making the main lobe "fatter". All in all, though, such a small difference that you'd never see it in real life. Jim, W6RMK _______________________________________________ See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread [TowerTalk] horizontally polarized antennas and salt water, Stephen Reichlyn Re: [TowerTalk] horizontally polarized antennas and salt water, Pete Smith Re: [TowerTalk] horizontally polarized antennas and salt water, Jim Lux Re: [TowerTalk] horizontally polarized antennas and salt water, Pete Smith Re: [TowerTalk] horizontally polarized antennas and salt water, Jim Lux <= RE: [TowerTalk] horizontally polarized antennas and salt water, Juan M. Chazarra EA5RS Re: [TowerTalk] horizontally polarized antennas and salt water, Terry Gerdes Re: [TowerTalk] horizontally polarized antennas and salt water, Jim Lux Re: [TowerTalk] horizontally polarized antennas and salt water, Alan Zack