Return-Path: Received: from mtain-dh05.r1000.mx.aol.com (mtain-dh05.r1000.mx.aol.com [172.29.65.25]) by air-de01.mail.aol.com (v129.4) with ESMTP id MAILINDE014-5ea54ca0d955112; Mon, 27 Sep 2010 13:50:13 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh05.r1000.mx.aol.com (Internet Inbound) with ESMTP id BA1C838000133; Mon, 27 Sep 2010 13:50:11 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1P0Hoo-0002l2-F7 for rs_out_1@blacksheep.org; Mon, 27 Sep 2010 18:48:50 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1P0Hoe-0002k5-0A for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 18:48:40 +0100 Received: from out1.ip01ir2.opaltelecom.net ([62.24.128.237]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1P0Hoc-00058K-Vw for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 18:48:41 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AlsFADd1oExOk8J1/2dsb2JhbACQJAOGSosmcckkhUQEgVyLcoJM X-IronPort-AV: E=Sophos;i="4.57,244,1283727600"; d="scan'208,217";a="325326987" Received: from unknown (HELO xphd97xgq27nyf) ([78.147.194.117]) by out1.ip01ir2.opaltelecom.net with SMTP; 27 Sep 2010 18:48:33 +0100 Message-ID: <007701cb5e6c$33047480$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Mon, 27 Sep 2010 18:48:31 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: Loops on TX Content-Type: multipart/alternative; boundary="----=_NextPart_000_0074_01CB5E74.94994100" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE 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-global-disposition: S X-AOL-REROUTE: YES x-aol-sid: 3039ac1d41194ca0d953704c X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0074_01CB5E74.94994100 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable In the past, experiments on antenna test sites indicate a vertical loo= p performs best if the bottom wire of loop is about 7 ft above ground.= =20 VE2CW I think did comprehensive tests with such antennas, as an alt th= ere is the grounded loop, half the size at natural resonance is above= ground and earth acting as the other half. Small loops in relation to freq on TX are inefficient, but acceptable= for RX All this info has been documented over the years, some research will= reveal results de g3kev ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Monday, September 27, 2010 6:24 PM Subject: LF: Loops on TX Good to see the reflector back again. For the last week or so I've been running my vertical "fully in the= air" TX loop (1mm diameter wire, 80m sq area) on both 137 and 500kHz.= Now, the bottom of the loop is laying right on the lawn with no attem= pt to raise it off the ground. Weather has been mixed and yesterday it= rained all day. Results on 500kHz suggest it is every bit as good (ac= tually better) than my top loaded Marconi used last winter with best= DX so far with 2mW ERP being LA3EQ last evening (heavy rain all day= and evening). Results on 136kHz with <20uW ERP have been encouraging= too with 6 different WSPR reports out to 148km. I clearly know that= improving the wire diameter will improve the ERP simply as a result= of reducing resistive losses. What I'm less clear about is why people= say all of the loop should be raised above the ground. My questions are these: a.. What additional losses, if any, do I suffer having the loop on= the ground (even wet ground)? How do these arise? b.. Could I bury the return part of the loop wire in the ground an= d maybe gain a few more square metres of area?=20 c.. Is there anywhere where I can get a simple explanation of loop= losses due to ground presence and foliage presence? In the last year a lot of accepted theory/beliefs, for example on ea= rth electrode antennas, has proved to be questionable and I am wonderi= ng if the "loop must be in the air and away from foliage" is another= accepted "fact" which needs to be questioned. 73s Roger G3XBM --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 ------=_NextPart_000_0074_01CB5E74.94994100 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
In the past, experiments on antenna= test sites=20 indicate a vertical loop performs best if the bottom wire of loop is= about 7 ft=20 above ground.
VE2CW I think did comprehensive tests= with such=20 antennas, as an alt there is the grounded loop, half the size at natur= al=20 resonance is above ground and earth acting as the other half.
 
Small loops in relation to freq on TX= are=20 inefficient, but acceptable for RX
All this info has been documented ove= r the years,=20 some research will reveal results
de g3kev
 
----- Original Message -----
Sent: Monday, September 27,= 2010 6:24=20 PM
Subject: LF: Loops on TX

Good to see the reflector back again.

For the= last week=20 or so I've been running my vertical "fully in the air" TX loop (1mm= diameter=20 wire, 80m sq area) on both 137 and 500kHz. Now, the bottom of the lo= op is=20 laying right on the lawn with no attempt to raise it off the ground.= Weather=20 has been mixed and yesterday it rained all day. Results on 500kHz su= ggest it=20 is every bit as good (actually better) than my top loaded Marconi us= ed last=20 winter with best DX so far with 2mW ERP being LA3EQ last evening (he= avy rain=20 all day and evening). Results on 136kHz with <20uW ERP have been= =20 encouraging too with 6 different WSPR reports out to 148km. I clearl= y know=20 that improving the wire diameter will improve the ERP simply as a re= sult of=20 reducing resistive losses. What I'm less clear about is why people= say all of=20 the loop should be raised above the ground.

My questions are= these:
  • What additional losses, if any, do I suffer having the loop on= the=20 ground (even wet ground)? How do these arise?
  • Could I bury the return part of the loop wire in the ground an= d maybe=20 gain a few more square metres of area?=20
  • Is there anywhere where I can get a simple explanation of loop= losses=20 due to ground presence and foliage presence?
In the last= year a lot=20 of accepted theory/beliefs, for example on earth electrode antennas,= has=20 proved to be questionable and I am wondering if the "loop must be in= the air=20 and away from foliage" is another accepted "fact" which needs to be= =20 questioned.

73s
Roger G3XBM

--
http://g3xbm-qrp.bl= ogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM   GQRP=20 1678    ISWL G11088
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