Return-Path: Received: from rly-mf04.mx.aol.com (rly-mf04.mail.aol.com [172.20.29.174]) by air-mf03.mail.aol.com (v121.4) with ESMTP id MAILINMF033-9564795fd4dc1; Tue, 22 Jan 2008 09:27:31 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mf04.mx.aol.com (v121.4) with ESMTP id MAILRELAYINMF044-9564795fd4dc1; Tue, 22 Jan 2008 09:27:27 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1JHK5r-0005n9-Io for rs_out_1@blacksheep.org; Tue, 22 Jan 2008 14:27:15 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1JHK5q-0005n0-Vg for rsgb_lf_group@blacksheep.org; Tue, 22 Jan 2008 14:27:15 +0000 Received: from pne-smtpout2-sn2.hy.skanova.net ([81.228.8.164]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1JHK5n-0008FO-Bh for rsgb_lf_group@blacksheep.org; Tue, 22 Jan 2008 14:27:14 +0000 Received: from [127.0.0.1] (62.20.250.132) by pne-smtpout2-sn2.hy.skanova.net (7.3.129) (authenticated as u33233109) id 478BD00D00245FBF for rsgb_lf_group@blacksheep.org; Tue, 22 Jan 2008 15:27:03 +0100 Message-ID: <4795FD3B.603@telia.com> Date: Tue, 22 Jan 2008 15:27:07 +0100 From: "Johan H. Bodin" User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <000501c85c3d$4fa2f820$0b01a8c0@weazle> <20080122135712.5D7C8F3862@smtps02.kuleuven.be> In-Reply-To: <20080122135712.5D7C8F3862@smtps02.kuleuven.be> X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Fenceline longwire Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-AOL-IP: 193.82.116.20 X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_helo : n X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_822_from : n X-Mailer: Unknown (No Version) Rik Strobbe wrote: > It seems that (at least in theory) even 1200 foot is too short to be > long on 500kHz ... > Or does MMANA not work properly ? Hello Rik, MMANA works very well for free space models but since it is based on MiniNEC, it does not properly model how the "real world" ground interacts with the near field. As far as I know, it uses the ground parameters for the far field calculations only. In other words, I don't think MMANA is able to make meaningful performance predictions for small antennas close to non-perfect ground. I just put a 2000m horizontal wire into MMANA and tried different heights from 1cm to 1m on 500kHz with real ground. Both gain and impedance figures were ridiculous, >600dB gain difference and sometimes the real part of the impedance was negative! :-D Beverages rely on non-perfect ground to work so I saw no reason to trust the radiation patterns either. 73 Johan SM6LKM