[TowerTalk] 4-Square Configurations

[K3BU@aol.com]

In a message dated 8/16/2000 1:04:32 PM Eastern Daylight Time, 
w8ji@contesting.com writes:

> 
>  That's one of the MANY reasons I avoid small numbers of elevated 
>  radials Yuri.
>  
>  The radial system radiates a considerable amount in the nearfield 
>  area, the strength of induction fields is very large around the 
>  radials. They produce strong electric and magnetic fields, the fewer 
>  the radials the stronger the fields near each radial.
>  

and they make that vertical over ground screen or at the ocean front work 
more efficiently, no losses in spreadout and dumpened in ground radials. I 
agree with you if you are talking about inland, inclear vertical 
installation, but that special case as 6Y2A proved works and is worth it!

>  Because of that, they induce lots of unwanted signal into any other 
>  conductor near the radials. If that conductor happens to be another 
>  antenna, and if the transmitter has poor output filtering, you can 
>  generate mixing products in the output device that re-radiate.
>  

True in small lot installation or congested area. No concern in contest setup.

>  A second problem is common mode currents. As far as feedline 
>  currents, small ground systems on Marconi antennas really 
>  aggravate the problem. It often requires multiple chokes on the 
>  feedline to clean the system up. It doesn't take much common 
>  mode current to screw up a modern radio, in particular because the 
>  microphone grounds and keyer grounds are often not grounded at 
>  all at the case entrance of the radio.
>  

Ditto as above. Actually I am shooting for two radios on the same band setup, 
where I can (with 2nd RX) get close to my CQing freq while transmitting.

>  ***The same problems can occur center feeding vertical dipoles, 
>  where a single choke at the feedpoint often isn't enough. 
>  It doesn't surprise me that they had problems in a multi-multi.
>  

That WAS a problem with two antennas being too close. 

73 Yuri  <A HREF="http://members.aol.com/k3bu/index.htm">K3BU</A>

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