[TowerTalk] Unique Inv L...Help!

[Donald Chester]

> From your description of your LW, you must have about 160 feet of 
>antenna horizontal and about 100 feet vertical.  That's a total of about 
>a half wave on 160, a very bad length to try and match.  
> 
>Jerry, K4SAV

What is so difficult about trying to match a half wave antenna, fed at one end?  I have done this many times without difficulty, by using a parallel tuned circuit, with one end connected to the ground system and the other end connected to the antenna.  It can be fed by tapping the transmission line a few turns from the bottom end of the coil, or by winding a coupling link at the bottom end of the coil.  With proper placement of the tap or by carefully adjusting the number of turns on the link, a perfect 1:1 match to the transmission line can be achieved.

An alternative is to wire the transmission line in series with the bottom end of the coil, with the shield of the coax connected to the ground system and the centre conductor connected to the bottom end of the coil. This forms a simple L-network. A perfect match can be had by adjusting the number of turns on the coil along with the setting of the variable resonating capacitor.

Don, k4kyv


 

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