[Lf] A real LF ANTENNA !

[Andre' Kesteloot]

Hello Malcolm,
an impressive set-up indeed, the details of which I am relying to our LF
group here.
The fact that you are located on the East Coast of England may not be as bad
as we thought originally, if indeed we need for the signal to bounce on the
D layer a couple of times. I suppose it will depend on the angle of attack.
73 & merry Christmas
Andre' N4ICK


malcolmg3kev wrote:

> Hi Andre. Thanks for your message about my antenna.
> My antenna is supported on a commercial 5 section telescopic tower, 100
> ft high, made by Strumech UK. The antenna system consists of 3 x inv L
> antennas. Each one is 100 feet vertical and each one has a top section
> of 250 feet. These are supported by the tower and placed out from the
> tower about 8 feet. The bottom of each inv L is connected together and
> also connected to my base loading inductor of about 1.2 mh. The bottom
> of the inductor goes to ground and my network of inuslated radials lying
> on top of the ground. The 50 ohm coax coming from my shack about 150
> feet away is matched into the base loading inductor. The coax
> shield/braid is connected to earth/radials but the centre of the coax is
> tapped up the coil to obtain a 50ohm match. I therefore have a perfect
> 50 ohm match to my TX/RX which is located 150 feet away in the house.
> The swr is 1:1. Once the system is set up and resonant is is very stable
> and seldom needs any re-adjustments except I make a large frequency
> excursion. Useable bandwidth about +or - 200 hz. I like a low swr so do
> not venture outside those limits without re-adjusting the loading
> inductor.
> The earth/radial system here consists of one earth spike at the base of
> the loading inductor, also at this point is connected 20 insulated 2.5mm
> radials each 40 metres long. I have two longer insulated radials each 80
> metres long. I might try say 3 elevated radials some time, but only
> about 1 metre of the ground. I could go higher but that would have the
> effect of reducing the virtual height of my antenna so what I would gain
> one way I would lose the other.
> I estimate my total ground loses to be around 60 ohms. My natural ground
> is clay and there is a river about 200 yards away on one of my boundries
> also the sea is about 2 miles to my east.
> Because of my type of ground it might be worth trying just a good earth
> spike and no radials giving me a virtual height of 200 ft. As the water
> table changes I might have to re-adjust more often, but it might be
> worth trying.
> I am currently running 600 watts rf out to the base of the antenna and
> understand from those that I work in EU and around the UK that I am the
> strongest signal from G-land. Apart from my installation, and as far as
> I know there are only 2 other stations with good antenna systems MM0ALM
> near Aberdeen/Scotland with two 140 feet towers and 350 watts rf out to
> his antenna. GI3PDN near Antrim/N.Ireland with one 80 ft  tower but at
> present he only runs 130 watts rf out to the antrenna.
> The others on the band do well locally and across to near europe but the
> chances of working anything beyond are remote, because of their low and
> short antennas.
> I suppose I might be in with a chance to work the USA but I am the
> furtherest away from you on the East Coast of England. GI3PDN if he had
> more power would be nearest to you, then EI0CF at Malin Head, Donegal
> Eire, but his antenna is only about 50 ft high. MM0ALM is again far away
> from you but with good antennas and reasonable power.
> I hope this information is useful and hope to hear from you again. Have
> a Merry Xmas and HNY. de Malcolm/G3KEV(Retired Radio
> Officer/Aeronautical/Marine and Fixed Services)