Message-ID: <00bb01ccc9ad$68c13740$0401a8c0@xphd97xgq27nyf>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <008301ccc97c$51d9fcf0$0401a8c0@xphd97xgq27nyf> <DD1655CA1C374DD9B72C8757559BEABF@JimPC>
Date: Tue, 3 Jan 2012 00:19:50 -0000
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Subject: LF: Re: Re: Antennas
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Jim
For a radio amateur you could start with a  compromise. Get a modest sized
120 ft mast and run out a V- Beam configuration say each leg 600 feet
long, each wire secured at the far ends to similar masts or if you are
lucky,  trees of a similar height. Resonate this on LF or MF and compare the
results against the hand held micro antennas. This on LF is small compared
to the real thing but certainly allows you to HEAR DX signals of sufficient
strength
to have an audible CW or SSB qso. One other benefit, it can be used as a TX
antenna.
Another approach, use the mast as a support and configure the wires into 2 x
inv L antennas in parallel, resonate and use as a TX/RX antenna something
that cannot be done with a micro probe or hand held ferrite stick.
On MF the system could be re- configured as a 1/4 wave giving respectable
results. Do not forget to lay out a few insulated ground radials to enhance
performance.
On commercial International radio point to point communications sites the
masts were hundreds of feet and in some cases ove 1000 feet high. Most have
been dismantled because the bulk of commercial radio traffic is via
Satellite. There might be some Govenment and Broadcast LF es MF large arrays
still about.
Rhombics and V-Beam arrays were very common some years ago on most
commercial sites and I never encountered anyone wobbling  ferrite sticks
about!!!!!!!!!!!!!!!!
Signals had to be AUDIBLE to be useful and were also relatively high speed
compared to the Amateur approach of QRS 60 - 6000 visible only in most cases
and not practicable to shift masses of commercial radio traffic.
You would need to Research the subject to further your education


g3kev



----- Original Message -----
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Monday, January 02, 2012 8:03 PM
Subject: LF: Re: Antennas


> Dear Mal, LF Group,
>
> >When I was in the business some years ago on LF/MF Rhombics and V-Beams
> >were the norm
> >de mal/g3kev
>
> Since rhombic and vee designs usually end up at least a few wavelengths
> long, and more than half a wavelength high, an LF rhombic would be a truly
> gigantic structure. I don't believe masts high enough to support such an
> antenna have ever been built - can you give any examples?
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
>