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Re: LF: Re: Re. DECCA Tx

To: [email protected]
Subject: Re: LF: Re: Re. DECCA Tx
From: "Toni Baertschi" <[email protected]>
Date: Wed, 29 Mar 2000 12:32:45 -0800
Organization: Phonak Communications AG
References: <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
A sort of passive amplifier: The low radiated power of the small antenna is 
captured
by the big antenna, maybe 100m away, mysticly amplified and then radiated again 
-
giving a much stronger signal? How does this work?

73 de Toni, HB2ASB

g3kev wrote:

Dave Brown wrote:

> Laurie,
> I think you will find that you need to remove the 300 footer before trying
> the low height antenna- otherwise mutual coupling effects will surely stuff
> things up.
>  And at 300 feet you will be getting out of 'very short vertical' territory
> anyway, even on 136.

At this frequency with both antennas resonant on 136 khz on the same site, the
induced rf from the small vertical into the larger one would distort any
meaningful tests. The antennas would need to be sited several kilometres apart,
when co located one would need to be dismantled while the other one is tested.
I have already tested this by starting off with a 60 ft vertical and progressing
to 120 ft and it certainly made a big difference for the same given rf power
output. Signal reports all over europe confirm this.
G3KEV

>
>
> 73
> Dave, ZL3FJ
>
> ----- Original Message -----
> From: LAWRENCE MAYHEAD
> To: rsgb lf group
> Sent: Wednesday, March 29, 2000 7:32 AM
> Subject: LF: Re. DECCA Tx
>
> The possibility of transmitting from an ex Decca site is very intresting I
> would like to put foreward a suggestion for an experiment.Theory has it that
> the radiation pattern for a much shortened vertical is not dependant on
> height!  Some on this reflector disagree.Would it be possible to radiate say
> 1w erp from the 300 foot antenna and  the same power from a co-sited very
> short vert similar to those being used by many people, if they used the same
> ground system all the better.Then by transmitting alternately from each
> station we could gather signal reports from many recieving stations both
> near and far,for various times of the day.
> Perhaps then we could settle this argument once and for all.. 73s Laurie.


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