Return-Path: Received: (qmail 6825 invoked from network); 25 Feb 2001 19:19:28 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by extortion.plus.net with SMTP; 25 Feb 2001 19:19:28 -0000 Received: (qmail 14295 invoked from network); 25 Feb 2001 19:19:26 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 25 Feb 2001 19:19:26 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14X6T8-00058F-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 25 Feb 2001 19:04:30 +0000 Received: from mta3-rme.xtra.co.nz ([203.96.92.13]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14X6T6-000585-00 for rsgb_lf_group@blacksheep.org; Sun, 25 Feb 2001 19:04:29 +0000 Received: from xtr743187 ([202.27.181.119]) by mta3-rme.xtra.co.nz with SMTP id <20010225190348.TTXM13669018.mta3-rme.xtra.co.nz@xtr743187> for ; Mon, 26 Feb 2001 08:03:48 +1300 Message-ID: <002801c09f5e$991f9560$77b51bca@xtr743187> From: "Vernall" To: rsgb_lf_group@blacksheep.org References: <001a01c09e42$95b26320$cb9e74d5@w8k3f0> Subject: LF: Re: Measuring resistance of aerial system Date: Mon, 26 Feb 2001 07:36:57 +1300 MIME-Version: 1.0 Content-Type: text/html; charset=windows-1252 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2919.6600 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Content-transfer-encoding: 8bit

Dick PA0SE,

Regarding your observed losses being higher in damp conditions:

It amazes me that the resistance is lower in summer than in winter. I had expected the opposite.

There are no trees near the aerial.

When it rains or in fog the resistance rises considirable, as indicates by the aerial current dropping by up to 25%.

Could that be due to water particles being heated in the field around the aerial? Or is it only caused by increased leakage via the aerial insulators and the feed-in?

You could check for leakage on the antenna wire with a "megger". You may also have induced losses in the wall of your house and loss happens to vary with moisture conditions (could be checked before and after a hosing down). A possible countermeasure is to increase the spacing of the antenna "upwire" from other objects (which reduces the field strength and induction loss in the other surface?).

73, Bob