Hi Mal,
How do normal humans, living in semi-detached homes with tiny gardens, erect a
"modest sized" 120 foot mast with 600 foot legs? :-)
The issue is maximising RX S/N by whatever means are available, but the
solutions will heavily depend on individual situations and space and especially
local noise. For many, small loops and E-field probes are an excellent
solution.
73s and a happy New Year to you.
Roger G3XBM
-- Via my iPod Touch 4g --
On 3 Jan 2012, at 00:19, "mal hamilton" <[email protected]> wrote:
> 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" <[email protected]>
> To: <[email protected]>
> 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
>>
>>
>>
>
>
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