[GreenKeys] rtty 101

[Roy Norris]

Hi Gil,

A good ground system or system of radials/screen will significantly improve 
the performance of a vertical antenna.  On my trawler, copper screen is 
bonded into the roof of the pilot house and it helped significantly with 
the vertical antenna I used on marine HF SSB.  The basic rule is that the 
dimensions of the ground system (either a large number of wires radiating 
from the base of a ground screen needs to be at least 1/4 wave at the 
lowest operating frequency for best effect. ( For example, about 65 feet in 
radius for 3.5 Mhz and above or 33 feet for 7 Mhz and above. If this cannot 
be achieved, then the dimension should be as long as possible.  A 
combination of ground screen and radials will also work well.  Perhaps four 
or more radials at least 1/4 wavelength long and a ground screen as large 
as practicable.  It is important that the screen and the radials all be 
bonded together with low resistance connections.  If the screen is made of 
copper wire, then it needs to be soldered at its seams.  Radials should be 
soldered to the ground screen as well and the entire ground system 
connected to the shield of the coax feed line.  The separation between the 
base of the vertical antenna and the ground system is not critical as long 
as it is within several feet or so.

Another important consideration is to use low resistance material for the 
ground system. Copper wire and copper screen being preferable.

Good luck  -- Roy, KEEG

At 02:27 PM 2/14/2003 -0700, you wrote:
>Hi folks:
>
>Thanks to everyone who replied (on-list and many off-list).
><snip>
>After I get antenna mounting locations ready, I was thinking of just
>putting some conduit to the locations, and adding coax and ground wires
>later.  I was also considering some sort of ground under the vertical --
>discussions on radials seem to vary for number/length etc.  What about
>simply stapling some wire mesh to the ceiling joists before sheetrock goes
>up?  The "attic" is only about a foot high, so this "groundplane" would be
>almost directly under the vertical.  Or is it better to plan a proper
>radial setup for something like 20m?


<snip>

>gil
>
>
>
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