Another ¼ λ Ground Plane for 70 cm

The elements of this antenna are cut from 3/8" aluminium tubing. The length of the driven element is 6½" and that of the the radials 6¾".

The connector is SO-239.

Another ¼ λ Ground Plane for 70 cm

The radials are fastened to the connector flange after their mounting ends are flattened and drilled. They are then bent, making an angle of 30 degrees to vertical, with the connector flange corners taking the bend.

The driven element is fixed to the SO-239 centre terminal using a brass bush. A plastic sleeve makes the joint water-tight. The open end of the driven element is then sealed with rubber compound.

SWR at 435MHz is 1.5:1.

Related post: Twin-Radial ¼ λ Ground Plane for 70 cm
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Twin-Radial ¼ λ Ground Plane for 70 cm

The driven element of this antenna is a telescopic whip. It is mounted in a tubular aluminium pill box using polythene end-caps as insulators. A BNC flange-type socket is mounted on the bottom end-cap, with its centre pin soldered to the whip.

Twin-Radial ¼ λ 70 cm Ground Plane

Two aluminium-strip radials are bolted on to an aluminium base plate, beneath which the driven element assembly is attached. The whip clears the base plate through a central hole.

Mounting screws ensure that the base plate and the BNC flange make contact with the pill box.

SWR at 435MHz is better than 1.5:1.

Related post: A ¼ λ Ground Plane for 70 cm
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