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Date: Thu, 1 Apr 2010 12:02:10 +0100
Message-ID: <o2kfc7eccec1004010402n7f00e1c3l8b88ea090c0fb8bb@mail.gmail.com>
From: Andy Talbot <andy.g4jnt@googlemail.com>
To: rsgb_lf_group@blacksheep.org
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Subject: LF: E-Field Probe calibration question
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I have a calibrated E Field antenna (Procomm AAC-1) with a quoted
antenna-factor of 0.15V into 50 ohms when placed in a field of 1V/m,

This is mounted in the centre of a car roof and fed via a bulkhead connector
to a calibrated measuring receiver inside the vehicle, which we can assume
is a Faraday cage at LF,  S0 my question is :    How is the effective height
of the antenna changed?    It was 0.15m - the specification said so - but
this would have been over an infinite groundplane.  Do I regard the body of
the car as being the other half of a dipole?  In which case, at 1.5m it adds
20dB to the received signal and makes a mockery of calibrated measurement of
the E-Field value..

Is it worth persuing this route, or better to stick to untuned loops for
calibrated E-Field measurements at LF/MF?


Andy
www.g4jnt.com

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<div>I have a calibrated E Field antenna (Procomm AAC-1) with a quoted ant=
enna-factor of 0.15V into 50 ohms when placed in a field of 1V/m,</div>
<div>=A0</div>
<div>This is mounted=A0in the centre of a car roof and fed via a bulkhead=
 connector to a=A0calibrated measuring receiver inside the vehicle, which=
 we can assume is a Faraday cage at LF,=A0 S0 my question is :=A0=A0=A0 Ho=
w is the effective height of the antenna changed?=A0=A0=A0 It was 0.15m -=
 the specification said so -=A0but this would have been over an infinite=
 groundplane.=A0 Do I regard the body of the car as being the other half=
 of a dipole?=A0 In which case, at 1.5m it adds 20dB to the received signa=
l and makes a mockery of calibrated measurement of the=A0E-Field value..</=
div>

<div>=A0</div>
<div>Is it worth persuing this route, or better to stick to untuned loops=
 for calibrated E-Field measurements at LF/MF?</div>
<div>=A0</div>
<div><br clear=3D"all">Andy<br><a href=3D"http://www.g4jnt.com">www.g4jnt.=
com</a><br></div>

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