References: <008301ccc97c$51d9fcf0$0401a8c0@xphd97xgq27nyf> <DD1655CA1C374DD9B72C8757559BEABF@JimPC> <00bb01ccc9ad$68c13740$0401a8c0@xphd97xgq27nyf>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
In-Reply-To: <00bb01ccc9ad$68c13740$0401a8c0@xphd97xgq27nyf>
Message-Id: <B5A3831D-F6D7-457C-A5D7-443EDE8198B3@gmail.com>
Date: Tue, 3 Jan 2012 07:58:12 +0000
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: Re: Re: Antennas
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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 solu=
tions will heavily depend on individual situations and space and especially l=
ocal noise.  For many, small loops and E-field probes are an excellent solut=
ion.=20

73s and a happy New Year to you.=20

Roger G3XBM

-- Via my iPod Touch 4g --

On 3 Jan 2012, at 00:19, "mal hamilton" <g3kevmal@talktalk.net> 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 t=
he
> 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 sufficien=
t
> strength
> to have an audible CW or SSB qso. One other benefit, it can be used as a T=
X
> 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 enhanc=
e
> 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 hav=
e
> been dismantled because the bulk of commercial radio traffic is via
> Satellite. There might be some Govenment and Broadcast LF es MF large arra=
ys
> 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 cas=
es
> and not practicable to shift masses of commercial radio traffic.
> You would need to Research the subject to further your education
>=20
>=20
> g3kev
>=20
>=20
>=20
> ----- 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
>=20
>=20
>> Dear Mal, LF Group,
>>=20
>>> When I was in the business some years ago on LF/MF Rhombics and V-Beams
>>> were the norm
>>> de mal/g3kev
>>=20
>> 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 trul=
y
>> gigantic structure. I don't believe masts high enough to support such an
>> antenna have ever been built - can you give any examples?
>>=20
>> Cheers, Jim Moritz
>> 73 de M0BMU
>>=20
>>=20
>>=20
>=20
>=20