Re: [HCDX] K9AY on a 7-storey building?

[Hermod Pedersen <hermod.pedersen@xxxxxxxxxxxxx>]

Karel Honzik wrote:

>does the K9AY antenna work on a flat roof of a multi-storey building (e.g. 
>a 7-storey
>one)? Is there anybody who knows more? I know that K9AY needs proper 
>grounding which
>perhaps is not possible to provide on a roof despite a grounding net is 
>installed...

Has been done quite successfully by several DXers. All that is needed is 
radials to create an artificial ground -- as described by Portugues DXer 
Carlos Goncalvez in the yahoo K9AY group:

Date: Wed Sep 24, 2003
Taking the loop so high may or
may not (I don't know) improve reception, but certainly improves noise pick
up by lowering its level, which is common theory.
That's one aspect. The other important aspect respects the way to make the
loop work in terms of nulling signals, meaning there must be a way to
(remotely) adjust the resistive termination of each loop at will. This is
normally achieved via certain components betwen one tip of the loop wire and
ground; while most users rely on a common ground connection to earth by
means of a ground rod or similar, there's also the possibility of creating
an artificial ground like for other antenna types, usually verticals that
amateurs with less available antenna space use for transmitting, and these
normally have radials, which is a "mirror", but then you must know this
stuff since you mention an amateur call-sign.
Consequentely, you can also use radials on the K9AY too to create an
independent ground system, usually termed as artificial ground: that's what
I first tested to see whether it could work, and use since then for my 2.60
m high K9AY (2 loops), i.e. the lowest part of the antenna is a set of four
4.5 m long radials that you can only reach by using a stepladder (hi!).
Those radials are my K9AY "ground." Needless to say the semi-horizontal
elements of each of the 2 loops are located even a bit higher: 2.60 + 0.5 m.
You can be sure my K9AY does work! Have a try too.
73,
Carlos,

- - - - - - - - - - - - - - - - - - - - - - - -
Hermod Pedersen, HCDX Antenna Editor
<http://www.hard-core-dx.com/nordicdx/antenna/> 

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