Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: LF: Horizontally polarised radiation

To: [email protected]
Subject: Re: LF: Horizontally polarised radiation
From: "g3ldo" <[email protected]>
Date: Wed, 7 Jan 2004 20:41:27 -0000
References: <000201c3d2f3$c4fb5f40$61e4fc3e@l8p8y6> <[email protected]> <000001c3d009$acf7a620$c7e47f50@Smisan> <[email protected]> <000601c3d2c3$2bd34e70$b733f7c2@johnb5a82ea1a4> <[email protected]> <000201c3d2f3$c4fb5f40$61e4fc3e@l8p8y6> <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>

Rik, ON4YD said
-----------------------------------
It is an "idée fixe" that a horizontal wire must radiate a horizontal
polarized EM-wave.
A nice example of a mechanical horizontal construction that radiates a
vertical polarized signal is the DDRR antenna.
So a large horizontal topload close to ground will in most cases improve the
antenna efficiency (reduce the loss resistance ... footprint theory) but the
radiated signal will be nevertheless mainly vertical polarized.
----------------------------------

Very true.
Some years ago I modelled my LF antenna with losses introduced based on
measured parameters.
My antenna showed a gain of -23dBi. The 3D pattern showed a half doughnut
with a -22dBi vertical null.  Maximum radiation was indicated at 12 degrees.
Polarisation was totally vertical.

I then modelled OH1TN's antenna comprising a 500m wire, 28m high. This
antenna showed a gain of 16dBi, which was based on average ground - the
'real world' parameters were not known. This antenna showed a broad
elevation gain of 16 to 70degrees with no doughnut dip in the centre. In
spite of this there was no detectable horizontal polarisation radiation.
Judging by signal reports this antenna (and QTH) is exceptionally good as a
receiving site.

I made a rectangle DDRR antenna for 14MHz for mobile use - it looked like a
roof rack. This indicated a small degree of vertical polarisation but this
may have been radiating from the vehicle itself.

Regards,
Peter, G3LDO





<Prev in Thread] Current Thread [Next in Thread>