Return-Path: X-Spam-DCC: paranoid 1290; 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 u389fiZK030866 for ; Fri, 8 Apr 2016 11:41:44 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1aoSr3-00031O-Mq for rs_out_1@blacksheep.org; Fri, 08 Apr 2016 10:37:29 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1aoSr3-00031F-9g for rsgb_lf_group@blacksheep.org; Fri, 08 Apr 2016 10:37:29 +0100 Received: from nm5-vm5.bullet.mail.ir2.yahoo.com ([212.82.96.112]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1aoSqx-0001QW-Un for rsgb_lf_group@blacksheep.org; Fri, 08 Apr 2016 10:37:28 +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=1460108243; bh=x60KGmqSVMwNrFxE+9E/tRDiBnyTXA8jypvpCH2hbQQ=; h=Date:From:Reply-To:To:In-Reply-To:References:Subject:From:Subject; b=kxl0JnLERyN/2YXV7VLjGK0gCEqp+vpOf0e9YGkE5B14nq0JqEcqn5ENL2el7TCIy7NGM7ib/RtKw4YQ+OUMP4suzqNwIM//Hx97DihlXO14I4/NiWNSZq0hbk+ieU2sbSqF6BHo7QgTv45OSImuczyUE6bD2ffrzCuCW8o9GS9Q4y3LE5IWHR00dELRXSn93jH327g/9LND24aSsjIcw6iqOu0B8BVqfTDGocEuhkdvcPzn5Wf+50FR7vysb3ybfuNvYs8u5/GnDp28yOlZ6CXLzhUpmyckTTSQ1bVevJhMAmL+tKtdE+M3RvFbwUXA+Vf+QJ6PMxPhXqy/Ufm3cw== Received: from [212.82.98.125] by nm5.bullet.mail.ir2.yahoo.com with NNFMP; 08 Apr 2016 09:37:23 -0000 Received: from [212.82.98.71] by tm18.bullet.mail.ir2.yahoo.com with NNFMP; 08 Apr 2016 09:37:23 -0000 Received: from [127.0.0.1] by omp1008.mail.ir2.yahoo.com with NNFMP; 08 Apr 2016 09:37:23 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 68547.64453.bm@omp1008.mail.ir2.yahoo.com X-YMail-OSG: VSv9ghgVM1lUHQ1iZsxBWfJaBg5qX4.oADU2BtAOBZPAn5bLOsMHkCwHTQHIck. .Czaf_paL3VHWbXgQWL6z4C_wnjvZf783z5AKUI4p9oPQCeVFueKvUHBlmBx_ZoPczSWDhQPtSH3 PffkuB24f9GnfN5wPx0XyRWetYSOeD9W50Y5ku8EN9UllteUxv_GyHEBYDLCXdJ3N_D.fsd3UFQR ppIGtHy27XMxCB8rHSFm3QcBBpGQs.NUVKFcK_urLsX.NPl6_3.6e4w6xYBlUWkGMN7gJfbukmwG j9yzRguop_kQieIm8x2ckEooHA02hOWB10uei4COUHAOtu15n.OQZk0tWPrITMYLkjaa5vC8stXt gActC6IcW9._qdc.C8CvLAYh0H6J5.fTVfQJE35pdIw2THmw5BpIWyBUIayE1Dadn5Zm2WMJD3mW bucSCm5YSB9gBgJejicxn76B6A4RviI5jTDUNHUs2T45Y42T68mXoWaVplNbZodAkF0_Bze7MgjHO Received: by 217.12.9.9; Fri, 08 Apr 2016 09:37:22 +0000 Date: Fri, 8 Apr 2016 09:36:48 +0000 (UTC) From: Chris Osborn To: "rsgb_lf_group@blacksheep.org" Message-ID: <747224627.2437401.1460108208360.JavaMail.yahoo@mail.yahoo.com> In-Reply-To: References: MIME-Version: 1.0 X-Scan-Signature: 4ad75ad27eb9a353f40105f6e3872b5c Subject: Re: LF: Re: RE: Field Strength Measurements Content-Type: multipart/alternative; boundary="----=_Part_2437400_1564898869.1460108208348" 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: 7615 ------=_Part_2437400_1564898869.1460108208348 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Many thanks for the rapid replies gentlemen; they are very much appreciated= . Rik, thanks for the explanation of the two formulae and I've inserted that = ERP formula into my spreadsheet now - excellent ! Alan, I take measurements in open fields to the south of Biggleswade and at= about 1 - 1.5 km distance from the transmitter.Noted about the advantages = of higher ground measurement but we're fairly flat around here - HI !I'll l= ook at the O/S map and see what I can do. Transmitting 56 watts my ERP was calculated as being 0.38 watts which just = seemed rather low.My aerial is a 40 m long inverted 'L' at 9m mean height w= ith a reasonable ground system. Making measurments of G4GIR's transmissions with his 260 watts at 16 km ret= urned a value of 0.88 watts ERP 73Chris G3XIZ =20 On Friday, 8 April 2016, 0:24, Alan Melia w= rote: =20 #yiv7247377934 P {MARGIN-TOP:0px;MARGIN-BOTTOM:0px;}Chris two other points= 1.=C2=A0 How far from the aerial are you taking the measurement .....you ne= ed to be at least 300 to 500 metres away2=C2=A0=C2=A0 Because of ground los= s problems even the best (fully in the clear)=C2=A0amateur short aerials me= asure around 5 to 6 dB low.(that is a 136kHz observation.) Often a better r= eading is taken say a mile away on slightly elevated ground to the aerial s= ite. Jim Moritz did tests in a field adjacent to the Puckeridge Decca mast,= with a 10m high inverted L. =C2=A0AlanG3NYK=C2=A0=C2=A0 ----- Original Message ----- From: Rik Strobbe To: rsgb_lf_group@blacksh= eep.org Sent: Thursday, April 07, 2016 11:24 PM Subject: LF: RE: Field Str= ength Measurements=20 Hello Chris, =C2=A0 (1) will give you the EMRP (Effective Monopole Radiat= ed Power) (2) will give you the EIRP (Effective Isotropic Radiated Power) T= he formula P =3D 0.0203252(Ed)^2 will give you the ERP (Effective Radiated = Power) =C2=A0 73, Rik=C2=A0 ON7YD - OR7T =C2=A0 Van: owner-rsgb_lf_group@= blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Chris Osborn [g3= xiz@yahoo.co.uk] Verzonden: donderdag 7 april 2016 23:58 Aan: LF Group Onderwerp: LF: Field Strength Measurements LF,=20 =20 I've recently resurrected my old RF field strength meter as designed by PA= 0SE and published in the LF Experimenters' Handbook. I've modifed it to mea= sure signals in the MF band and have calibrated it with a home made Helmhol= tz coil arrangement.=20 This question may have been raised before but PA0SE gives the formula for = deriving the transmitter power as=20 P =3D 0.0111 (Ed)^2=C2=A0 . . .=C2=A0=C2=A0 (1) =20 where E is the electrical field strength and d the distance=20 I've read in other places that the power from an isotropic radiator is=20 P =3D (Ed)^2 / 30=20 =20 i.e.=C2=A0 0.0333 (Ed)^2=C2=A0 . . . . (2)=20 My calculated radiated power seems rather low so I'm wondering whether I s= hould be using formula (2)=20 Any clarification would be most welcome.=20 73 Chris G3XIZ =20 =20 =20 =20 =20 =20 =20 ------=_Part_2437400_1564898869.1460108208348 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Many thanks for the rapid replies gentlemen; they are very much appreciate= d.

Rik, thanks for the e= xplanation of the two formulae and I've inserted that ERP formula into my s= preadsheet now - excellent !

Alan, I take measurements in open fields to the south of Bi= ggleswade and at about 1 - 1.5 km distance from the transmitter.
Noted about the adv= antages of higher ground measurement but we're fairly flat around here - HI= !
I'll l= ook at the O/S map and see what I can do.

Transmitting 56 watts my ERP was calculate= d as being 0.38 watts which just seemed rather low.
My aerial is a 40 m long inverte= d 'L' at 9m mean height with a reasonable ground system.

Making measurments of G4GIR's t= ransmissions with his 260 watts at 16 km returned a value of 0.88 watts ERP=

=
73
=
Chris G3XIZ


<= div id=3D"yui_3_16_0_ym19_1_1460107047080_2880">


On Friday, 8 April 2016, 0:24, Alan Melia <alan.melia@btinte= rnet.com> wrote:


Chris two other points
1.  How far from the aerial are y= ou taking the=20 measurement .....you need to be at least 300 to 500 metres away
2   Because of ground loss p= roblems even=20 the best (fully in the clear) amateur short aerials measure around 5 t= o 6=20 dB low.(that is a 136kHz observation.) Often a better reading is taken say = a=20 mile away on slightly elevated ground to the aerial site. Jim Moritz did te= sts=20 in a field adjacent to the Puckeridge Decca mast, with a 10m high inverted = L.=20
 
Alan
G3NYK
 
 
----- Original Message -----
From:=20 Rik Strobbe
Sent: Thursday, April 07, 2016 11:= 24=20 PM
Subject: LF: RE: Field Strength=20 Measurements

Hello Chris,
 
(1) will give you the EMRP (Effective Monopole Radiated Power)
(2) will give you the EIRP (Effective Isotropic Radiated Power)
The formula P =3D 0.0203252(Ed)^2 will give you the ERP (Effective R= adiated=20 Power)
 
73, Rik  ON7YD - OR7T
 
Van: owner-rsgb_l= f_group@blacksheep.org=20 [owner-rsgb_lf_group@blacksheep.org] namens Chris Osborn=20 [g3xiz@yahoo.co.uk]
Verzonden: donderdag 7 april= 2016=20 23:58
Aan: LF Group
Onderwe= rp: LF: Field Strength=20 Measurements

LF,

I've recent= ly resurrected my old=20 RF field strength meter as designed by PA0SE and published in the LF=20 Experimenters' Handbook.
I've modife= d it to measure=20 signals in the MF band and have calibrated it with a home made Helmholtz = coil=20 arrangement.

This questi= on may have been=20 raised before but PA0SE gives the formula for deriving the transmitter po= wer=20 as

P =3D 0.011= 1 (Ed)^2  . .=20 .   (1)

where E is = the electrical field=20 strength and d the distance

I've read i= n other places that=20 the power from an isotropic radiator is

P =3D (Ed)^= 2 / 30

i.e.  = 0.0333 (Ed)^2  .=20 . . . (2)

My calculat= ed radiated power=20 seems rather low so I'm wondering whether I should be using formula (2)

Any clarifi= cation would be most=20 welcome.

73
Chris G3XIZ=








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