6 METER LFA ANTENNA



I have always wanted to try EME on any band, but especially on 6 meters where I'm trying to make 100 countries. A new type of yagi has been developed by G0KSC called the LFA or Loop Fed Array. This antenna is reported as being lower noise than conventional yagis, so I started assembling parts. W6QUV offered to give me the 32 foot boom off an old antenna, so the hard part was done.

The element to boom clamps were made from some "Z" extrusion that was noched on the ends to allow hose clamps. Plastic insulators were made on the lathe and split to allow tightening on the .50 and .375 inch diameter elements. The reflector and all the directors were made of .375 inch aluminum tubing that were joined in the middle with a 6 inch piece of .25 tubing that was pop rivited in place. Standard 2 inch antenna clamps were used to attach to the boom.

The driven element is a horizontal loop attached at 2 points to the boom and fed at the rear position. The loop is made of .50 tubing with the 2 connections on the ends being made of .50 flat stock with .375 solid rod extending into the element ends. Six inches of tapped rod were used to allow for adjustment .




The mast is a telescoping tube system that was part of the military AS-2236/GRC equipment and supports the antenna at 20 feet. Due to the restrictions of my back yard, the antenna needed to look between the guy wires. The guy wires were replaced with insulated Phillystran. Smaller Phillystran is used for the vertical supporting guys.



The antenna only needs to be rotated about 80 degrees to the East. A heavy flat steel plate has a Rohn trust bearing mounted in the middle. An 18 inch actuator arm moves a 6 inch stand off channel to do the rotation. A fixed pully was made of plastic to operate a flat belt. The belt drives a 500 ohm pot to do direction monitoring and has a 2 to 1 gear reduction for better resolution.


The antenna has up to 60 degrees of elevation. The same type of 18 inch actuator is used for the elevation. The mast plate holds the actuator and the boom plate hangs on a pivot pin. Another arm operates an elevation pot.



Complete dimensions with conversion to inches is here.

An enhanced version of this antenna is here.




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