Message-ID: <006d01c99846$4af8ecd0$0301a8c0@mal769a60aa920>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <fc7eccec0902260816u68aa7394lc2adc64e2440b62e@mail.gmail.com> <4A11BD1B67394BDD9B3001D8F176B76F@DR2>
Date: Thu, 26 Feb 2009 19:13:20 -0000
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Subject: LF: Re: Re: LF Antennas - back to basics
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Hi Dave.
Your sketch looks like a HORIZ LOOP which would have different 
characteristics to a VERT LOOP.
It might be considered as a VERTICAL at 30 ft and top loaded.
73 mal/g3kev

----- Original Message ----- 
From: "dave.riley3" <dave.riley3@verizon.net>
To: <rsgb_lf_group@blacksheep.org>; <andy.g4jnt@googlemail.com>
Sent: Thursday, February 26, 2009 4:53 PM
Subject: LF: Re: LF Antennas - back to basics


> Glad you asked, Andy...  Hope this one makes it past the spam filter...
>
> Back in the commercial AM transmitter biz days I buried miles of extra
> copper in to poor conductivity soil and gained little or nothing.
> Then came Bill Ashloop who proved that a small transmit loop can do quite
> well.
> http://www.wireless.org.uk/loopy.htm
> http://www.w1tag.com/XESANT.htm
>
> So I surveryed the back yard which sits on very poor conductivity soil and
> therefore makes a loop appear to me more in free space and here are the
> advantages that I have found to date:
>
> No high voltage wire ends to start tree fires. No wasted power going into
> and out of the ground...
>
> Much less wire used in a LOOP transmit antenna. This #4 stranded HV wire
> rests inside of 100' sections of garden hose and is hoisted into trees 
> with
> help of compound bow and pull line.
>
> No top loading, no radials, much less noise on RX, E-Z to tune and weather
> does not affect the tuning much such as from rain or snow, and it acts 
> like
> a good vertical regardless of being much simpler.
>
> As for the CONS, well I just don't think of any...  Somebody??
>
> It works very well from 600M to 6M and is the only real antenna that I 
> still
> have.
>
> Various feeds as noted below will let you tune it down to SAQ@17kc which I
> always hear and also makes for superb DX on 6M in 'some directions'.
>
> ref: http://www.radiocom.net/600M/LOOP109.jpg
>
> Wish I had a El-Nec printout but can't seem to fit this version in to it.
>
> QSL SURE VIA E-MAIL
> 090226 0406   1 -29  0.0   0.503869  G4JNT IO90 23
> 090226 0610   3 -29  0.0   0.503869  G4JNT IO90 23
>
> Have a quiet night and TNX from Dave @ WD2XSH/17
>
>
>
>
>
>
>
>
> ----- Original Message ----- 
> From: "Andy Talbot" <andy.g4jnt@googlemail.com>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Thursday, February 26, 2009 11:16 AM
> Subject: LF: LF Antennas - back to basics
>
>
>> Having now been encouraged by being decoded now by at least two US
>> stations,  was wondering how much improvement in efficiency I could
>> scrape out of my existing antenna.  It is a Marconi Tee, the vertical
>> element consisting of three wires from the base tapering to 200mm
>> spacing at the top.  There it is attached to the centre of a a
>> capacity hat 15m long and 200mm wide made of three parallel wires.
>>
>> The ground system is a bit haphazard in my 7m wide by 12m long garden,
>> with about 4 wires meeting at the base of the antenna meandering
>> around the garden, starting off in different directions from teh base.
>> They are all connected to substantial ground rods in heavy clay  at
>> their far points, a with a few randomly spaced rods in between (I used
>> several 1m lengths of 15mm water pipe as well as proper rods - there
>> is probably about 9 or 10 rods in total, mostly 1 - 2m in length -
>> can't remember that far back!   Some of the earth conductors were also
>> bonded to the house wiring by a couple of substantial straps, and even
>> inside the house I added more straps at strategic places.   I also
>> ensured there was a good fat cable run directly under as much of the
>> capacity hat as possible.   As a test, disconnecting the PME earthing
>> bond and measuring the DC resistance between my total set of
>> connections and the incoming conductor ground/neutral point, the value
>> was a pretty consistent 3 ohms.  Haven't done this test for a few
>> years, but at the last check it was still of this order.
>>
>> Back in the 73kHz days a number of (mostly big!) stations were
>> surprised my signal was as strong as it was for probably the smallest
>> antenna in use then; G3LDO put it down to the fact I had concentrated
>> plenty of earthing wire to run directly under the top-hat.
>>
>> But, its all 14 years old,  still OK, but hopefully there's a wealth
>> of experience now, and I wonder if there are obvious improvements that
>> could be made:
>>
>> Firstly, bearing in mind there is no scope whatsoever to raise one end
>> of the capacity hat which is defined by the apex of the house roof,
>> and the other end would also need some major sugery to raise its heigh
>> substantially, that only leaves the middle, ie the height of the
>> actual radiator.    It wouldn't be too difficult to raise this to 10m
>> or even more with a fibreglass pole, but will I be throwing away all
>> the advantage by having the top-hat drooping down to 7m?
>>
>> Secondly, pictures of other peoples antennas aften show a substantial
>> grounding plate immediately under and around the antenna base.  Just
>> how far out is is worth going with a really substantial base.   I
>> could cut more conductors into the ground; while the ground is still
>> is still soggy in March may be a good time to do this.
>>
>> Any ideas please ...?
>>
>>
>> Andy  G4JNT
>> www.g4jnt.com
>>
>
>


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