Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mh05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 24D0B38000090; Wed, 3 Aug 2011 15:02:03 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Qoggr-0001EU-2z for rs_out_1@blacksheep.org; Wed, 03 Aug 2011 20:01:13 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Qoggq-0001EL-JE for rsgb_lf_group@blacksheep.org; Wed, 03 Aug 2011 20:01:12 +0100 Received: from mail-pz0-f42.google.com ([209.85.210.42]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Qoggn-0005aM-Lo for rsgb_lf_group@blacksheep.org; Wed, 03 Aug 2011 20:01:12 +0100 Received: by pzk37 with SMTP id 37so522218pzk.1 for ; Wed, 03 Aug 2011 12:01:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=fsq10Dl/H7U9IGHSn5JMa4c9qPcY3bh8CSA50QwW3F4=; b=b4kyCmH7e4UttJIBjZTTXsDgMSulyPbS2FqxxzPFKNeW3eeTdhAgZtiwwwYOFOhUvO J798InPRmvX//q9dGhmXNtgZKac3g8Jn/72ZITNrC+foeVmiGzW/sQsniPGORFJoKeGZ LOXEnpO8XbWh2N4pvCX7BRs5SicgzEvrFiMmA= MIME-Version: 1.0 Received: by 10.143.59.19 with SMTP id m19mr93783wfk.50.1312398061550; Wed, 03 Aug 2011 12:01:01 -0700 (PDT) Received: by 10.142.178.4 with HTTP; Wed, 3 Aug 2011 12:01:01 -0700 (PDT) In-Reply-To: References: Date: Wed, 3 Aug 2011 20:01:01 +0100 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Antennas Content-Type: multipart/alternative; boundary=001517401a44433d2004a99e7c36 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=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: G X-AOL-SCOLL-SCORE: 0:2:441887232:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d012.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d60d94e399b2b1542 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --001517401a44433d2004a99e7c36 Content-Type: text/plain; charset=ISO-8859-1 Mal You may be right about big antennas in a decent, quiet rural location but the majority of us now live close to modern civilisation with noise floors that have risen some 20-30dB or more at the lower end of the spectrum in recent years. Top Band is almost unusable here and 80m not a lot better. I am surprisingly lucky on 500kHz and 136kHz where I seem to be able to hold my own on receive with my loop antenna in its favoured directions. Many get very good results with PA0RDT type E-field probe antennas with careful location and after efforts to minimise noise pick-up. In the end S/N is all that matters so having a large antenna which increases both wanted signal *and* noise has no benefit as long as the S/N is as good as it can be. With more and more difficult noise environments in most urban and semi-urban locations I can see many people giving up amateur radio below 432MHz. I am tempted more and more to move up to the UHF and microwave region to get my next challenges and I live on the edge of a village where the noise must be far less of an issue than for my city friends. A little more understanding of the plight of many LFers in busy cities and some *encouraging* words and ideas would be good Mal. 73s Roger G3XBM On 3 August 2011 19:08, Chris wrote: > ** > Hi Mal and LF, > Well, all I can say is that here the signal to noise ratio on RX is better > on my PA0RDT than it is on my long wire (inverted 'L'). I have always > thought this a bit strange, quite often weak signals that cannot be seen on > the wire are perfectly copied on the PA0RDT. This applies from 136kHz to > 3.8MHz. I cannot see what else it can be other than local noise/QRM level. > 80m is another prime example where the noise has gradually got worse over > the years here. > Vy 73, > Chris, G4AYT, Whitstable, Kent. > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm https://sites.google.com/site/sub9khz/ --001517401a44433d2004a99e7c36 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Mal

You may be right about big antennas in a decent, quiet rural loc= ation but the majority of us now live close to modern civilisation with noi= se floors that have risen some 20-30dB or more at the lower end of the spec= trum in recent years.

Top Band is almost unusable here and 80m not a lot better. I am surpris= ingly lucky on 500kHz and 136kHz where I seem to be able to hold my own on = receive with my loop antenna in its favoured directions. Many get very good= results with PA0RDT type E-field probe antennas with careful location and = after efforts to minimise noise pick-up. In the end S/N is all that matters= so having a large antenna which increases both wanted signal and no= ise has no benefit as long as the S/N is as good as it can be.

With more and more difficult noise environments in most urban and semi-= urban locations I can see many people giving up amateur radio below 432MHz.= =A0 I am tempted more and more to move up to the UHF and microwave region t= o get my next challenges and I live on the edge of a village where the nois= e must be far less of an issue than for my city friends.

A little more understanding of the plight of many LFers in busy cities = and some encouraging words and ideas would be good Mal.

73sRoger G3XBM



On 3 August 2011 19= :08, Chris <c.ashby435@btinternet.com> wrote:
Hi Mal and LF,
Well, all I can say is that here the s= ignal to=20 noise ratio on RX is better on my PA0RDT than it is on my long wire (invert= ed=20 'L'). I have always thought this a bit strange, quite often weak si= gnals that=20 cannot be seen on the wire are perfectly copied on the PA0RDT. This applies= from=20 136kHz to 3.8MHz. I cannot see what else it can be other than local noise/Q= RM=20 level. 80m is another prime example where the noise has gradually got worse= over=20 the years here.
Vy 73,
Chris, G4AYT, Whitstable,=20 Kent.



--
http://g3xbm-qrp.blogspot.com/http://www.g3xbm.co.u= k
http://www.= youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/

--001517401a44433d2004a99e7c36--