Chuck, please explain how you are measuring - 6 dB null width. The entire back half of the antenna pattern is down at least 10 dB from beam peak with a DKAZ when measured at a typical elevation angle of 15 deg.
73 KAZ -----Original Message----- >From: Chuck Hutton <[email protected]> >Sent: Aug 21, 2015 5:01 PM >To: "[email protected]" <[email protected]> >Subject: Re: [IRCA] [NRC-AM] DKAZ Antenna > >Modelling numbers for a 20 x 140 DKAZ to back up what I said: - best null >is -42 dB and the -6 dB null width is 72 degrees. - lower the termination >by 80 Ohms and the best null (straight off the back) is only -29 dB but the 6 >dB null width jumps up to 106 degrees. >Chuck > >From: [email protected] >To: [email protected] >Subject: RE: [IRCA] [NRC-AM] DKAZ Antenna >Date: Fri, 21 Aug 2015 21:41:51 +0000 > > > > >This is a repeat of my earlier comment to Nick, where I guessed / thought that >the minima does not really move. >Ad I see it, the issue here is that the best null is the sharpest (narrowest) >null. If you want a null to cover something off to the side a bit, you can >indeed "mis-terminate" and get a wider null that hits the off-to-the-side >station. The price you pay is a degraded null in the backwards direction. >The way to prove this is to record termination and signal strength data for >someone directly in the null and someone off to the side. That's tough to do >from Grayland is you choose to face the antenna west for DX - there are few >stations directly in the eastward null. Unfortunately for testing purposes, it >would be better to face the antenna SW or SSW. >Chuck > > > >_______________________________________________ >IRCA mailing list >[email protected] >http://montreal.kotalampi.com/mailman/listinfo/irca > >Opinions expressed in messages on this mailing list are those of the original >contributors and do not necessarily reflect the opinion of the IRCA, its >editors, publishing staff, or officers > >For more information: http://www.ircaonline.org > >To Post a message: [email protected] > _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
