[TowerTalk] QST switchable antenna

[K8RI]

On 11/18/2011 4:50 PM, Jim Lux wrote:
> Well, I've got part of the model in.  Copied the dimensions from the QST
> article and the developer's MA presentation..
>
> Not getting a good match yet, nor the F/B... but it's probably some
> little fiddling needed with dimensions, etc.
>
Check the antenna handbook.  There's been one of these in there for 
years although I don't know if it was in the last one or not.  I'll have 
to check.

IIRC they bring the individual feed lines back to a remote antenna 
switch mounted on the mast.  The feedlines are a quarter wave with an RF 
Choke just before the antenna switch.  I don't remember if they ground 
the connections other than the active one or not.


73

Roger (K8RI)
>
> CM QST switchable
> CM Ashraf Abuelhaija design
> CM dimensions taken from slides Vortrag_MA_Abuelhaija_Ashraf.pdf
> CE 20m
> SY L = 5.3'wire length
> SY DR = .00021 ' wire radiu   (0.14 mm2)
> SY Hc = 7   ' height of center
> SY HE = 4.35    ' height of wire ends
> SY Y=4          'distance to side of antenna middle elements (fore aft Y=0)
> SY X1=4.62/2    'distance fore/aft for middle elements
> SY X=4
> SY CL = 120  ' pf Load
> GW	999	1	0.05	-0.05	HC	0.05	0.05	HC	DR	'feedpoint
> GW	10	50	0.10	0	HC	X	0	HE	DR	'wire #1
> GW	950	1	-0.05	-0.05	HC	-0.05	0.05	HC	DR	'loaded element feed
> GW	20	50	0.05	-0.05	HC	X1	-Y	HE	DR
> GW	30	50	-0.05	-0.05	HC	-x1	-y	HE	DR
> GW	40	50	-0.10	0	HC	-x	0	HE	DR	'wire #4, directly aft
> GW	50	50	-0.05	0.05	HC	-x1	y	HE	DR
> GW	60	50	0.05	0.05	HC	x1	y	HE	DR
> GE 1
> LD	5	0	0	0	58000000
> LD	0	950	1	1	0	0	CL*1e-12
> EX	0	999	1	0	1.0	0.0
> GN 2 0 0 0 13.0 .005 0.0 0.0
> FR 0 1 0 0 14.15 0.0 0.0 0.0
> EN
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