Re: LF: Re: Re: Antennas

["James.cowburn" <james.cowburn@virgin.net>]

Hi Mal

I wonder what your other country pursuits are?! I think Roger does a fab job with his restricted real easte and i guess on a km per erp basis he'll be up there with Anthorn-esque tower brigade!  my effective height is down at moment due to a gale bending my roach pole to 45 degrees and the inv l thrashing around! Happy new year all

Jim Cowburn

 mal hamilton <g3kevmal@talktalk.net> wrote:

Roger
You are missing the point. The argument is about small hand held antennas
versus large wire arrays fit for purpose to receive weak amateur radio
signals at AUDIO strength to enable one to have an aural QSO or exchange of
information. That is my view. The argument is NOT about who lives in a ONE
UP/ONE DOWN TERRACE OR SEMI.
Of course,  if you are interested in LF/MF and have limited space as you
state then you do the best you can and that is understood but has nothing to
do with the merits of large or small antennas.
Having been a radio amateur since the early 50's and having been brought up
on a small farm with plenty of antenna space I have likewise always owned
properties with sufficient space to accommodate radio towers, rotary beams
etc,  three at present and enough space for other country persuits.
therefore I am in a position to compare little against large. I stated
before that I had a Wellbrook loop antenna and it worked well but was poor
compared to an inv L at over 100 ft high and 500 ft long. I also built a
ferrite rod antenna and again it worked but was poor compared to the inv L
I can only report what I find and those that criticize by their own
admission are not in a position to compare the antenna to which I refer.
73 de mal/g3kev



----- Original Message -----
From: "Roger Lapthorn" <rogerlapthorn@gmail.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, January 03, 2012 7:58 AM
Subject: Re: LF: Re: Re: Antennas


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" <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
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
>>
>>
>>
>
>