Return-Path: X-Spam-DCC: paranoid 1170; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_MESSAGE,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u37M51fj029546 for ; Fri, 8 Apr 2016 00:05:01 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1aoHx5-0001oM-Ek for rs_out_1@blacksheep.org; Thu, 07 Apr 2016 22:58:59 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1aoHx5-0001oD-4a for rsgb_lf_group@blacksheep.org; Thu, 07 Apr 2016 22:58:59 +0100 Received: from nm8-vm6.bullet.mail.ir2.yahoo.com ([212.82.96.140]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1aoHx3-0008O2-C7 for rsgb_lf_group@blacksheep.org; Thu, 07 Apr 2016 22:58:58 +0100 X-DKIM-Result: Domain=yahoo.co.uk Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s2048; t=1460066336; bh=KU4aBbaEgDJUjq2WfTQ9cGJikHcuzoh6Uu7875Xhk00=; h=Date:From:Reply-To:To:Subject:References:From:Subject; b=TCfzcjmCr2BKZ0hR0lxgVX6vUVp0B/vOxNCYjZ8jIvaVDN8rugPaLNjhP3vI6NpjTuJtZMgd5t07LqAo+5qgtfewyNXYKTdjHEs48g1VQQ0RvHoyBnSbmTgamFINMj9iq6jc2OP5lbzX6vIuZHKOOoBV+Am2QYTeVkFmt/YjG8+qubbkLhsLWi2sxCS40bTFpeTKXAAcykTi+u8FLpF2KPYdeWkl4lNxe1vrGPSqUbrvelpJEcPlQApFot6ZhknJ+JTsDaQZ1Looelf6wegECgLxlUWs1qO8ASpYQb5YdXpDKNtsIDYBAdTT8ABDFciUPs8xW1l9ghHc5imLshh5jg== Received: from [212.82.98.52] by nm8.bullet.mail.ir2.yahoo.com with NNFMP; 07 Apr 2016 21:58:56 -0000 Received: from [212.82.98.102] by tm5.bullet.mail.ir2.yahoo.com with NNFMP; 07 Apr 2016 21:58:56 -0000 Received: from [127.0.0.1] by omp1039.mail.ir2.yahoo.com with NNFMP; 07 Apr 2016 21:58:56 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 65173.60740.bm@omp1039.mail.ir2.yahoo.com X-YMail-OSG: MHLWuYEVM1ktSOt3WnkdjibW7AarcudFb3cgzmbVBfwImAkxx71g0Ex7I9_HH80 l6iTQd6mVzo2nzb368vTQOFiah96Di6GLadpA5jrukJRMxFKOTUVaoAgFKHYmzxg5mRoACOObabY eoWbRIxwmdDl0Hn0MSu83DODh8gBhevQOQPE3O5wz1afkw84klIm0.nwlyS0ZgOl0kCUJV3VDwnQ OfYsZbExDHaduiBsc_H.PpdmITFRyQGbJAUSN.nz2f8atUpE4QxfWzft3.kixAWk535DebTmvAoc 05hAd4DndzKUUZGxQA9TVbpyPwrsXP3HlbRuduuKtoSno0OFHpJ8UQSdvv1ZC6IGLNNe_BLRQ8YN HjubXWwwPvu3rSVF5hy1WymgeiS1WliWg7GTwg_JvaCIghWB87Cc2ZYwEwVdbo_zdJkchV7T52PM tQsT_qCwSmApOCQFyZ6_0wROE0o0pS7HJvwP58HlBtu8bUH67mMvxx7dJS8jWccfqe_F3G9HhLz9 3hw-- Received: by 217.12.9.10; Thu, 07 Apr 2016 21:58:55 +0000 Date: Thu, 7 Apr 2016 21:58:55 +0000 (UTC) From: Chris Osborn To: LF Group Message-ID: <1840555212.2044542.1460066335241.JavaMail.yahoo@mail.yahoo.com> MIME-Version: 1.0 References: <1840555212.2044542.1460066335241.JavaMail.yahoo.ref@mail.yahoo.com> X-Scan-Signature: 61577e2058c0d3bf1737d7de6ed6eb16 Subject: LF: Field Strength Measurements Content-Type: multipart/alternative; boundary="----=_Part_2044541_173467730.1460066335236" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7609 ------=_Part_2044541_173467730.1460066335236 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable LF,=20 I've recently resurrected my old RF field strength meter as designed by PA0= SE and published in the LF Experimenters' Handbook.I've modifed it to measu= re signals in the MF band and have calibrated it with a home made Helmholtz= coil arrangement. This question may have been raised before but PA0SE gives the formula for d= eriving the transmitter power as P =3D 0.0111 (Ed)^2=C2=A0 . . .=C2=A0=C2=A0 (1) where E is the electrical field strength and d the distance I've read in other places that the power from an isotropic radiator is P =3D (Ed)^2 / 30=20 i.e.=C2=A0 0.0333 (Ed)^2=C2=A0 . . . . (2) My calculated radiated power seems rather low so I'm wondering whether I sh= ould be using formula (2) Any clarification would be most welcome. 73Chris G3XIZ ------=_Part_2044541_173467730.1460066335236 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
LF,

<= div id=3D"yui_3_16_0_ym19_1_1460064690028_2688">I've recently resurrected m= y old RF field strength meter as designed by PA0SE and published in the LF = Experimenters' Handbook.
I've modifed it to measure signals in the MF band and have calibrated i= t with a home made Helmholtz coil arrangement.

This question may have been raised before but PA0SE gives the for= mula for deriving the transmitter power as

P =3D 0.0111 (Ed)^2  . . .   (1)

where E is the electrical field strength and d the dis= tance

I've read in other places that = the power from an isotropic radiator is

P =3D (Ed)^2 / 30

i.e.  = 0.0333 (Ed)^2  . . . . (2)

My ca= lculated radiated power seems rather low so I'm wondering whether I should = be using formula (2)
=
Any clarificatio= n would be most welcome.

73
Chris G3XIZ







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