½ λ End-fed Sleeve Antenna for 70cm

One of the well-known end-fed ½ λ vertical antennas is the J-Pole. It's ¼ λ stub may be closed and fed at the point of lowest SWR or be kept open and fed at the ends (ARRL Handbook). A closed stub is first choice as it ensures DC ground and static-free operation. The sleeve variant of this is the Sperrtopf Antenna.

Notwithstanding the above, ease of construction prompted homebrewing of an end-fed sleeve antenna with an open-stub.

OE7OPJ OM Peter's plans for a 'Beer Can Antenna' fitted the bill.


 The 19¼" long driven element is cut from a length of 3/16" scrap copper tubing. A 2" diameter aluminium can, 6½" long, is used for the sleeve. Two PVC door buffers with 3/16" bores are used to hold the driven element centrally insulated from the can. One is press-fitted into the mouth and the other fastened with screws to the base of the can. A BNC socket is similarly fixed after it's centre pin is soldered to the driven element pushed out through a hole in the base of the can.

70 cm End-fed Sleeve Antenna
A tapered bakelite tube and a plastic end-cap complete the picture.

SWR at 435MHz is around 1.5:1.

Related post: A ¾ λ Ground Plane for 70cm
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Sleeve Dipole Antenna for 2m

The elements for this Sleeve Dipole Antenna are cut from copper tube scrap (3/16" diameter for the driven element and 5/8" for the sleeve).

2m Sleeve Dipole Antenna
The driven element is pushed into a 2" long rubber hose and fitted 1" deep into the sleeve. A tapered bakelite tube gives rigidity to the joint. For an overall length of ½ λ (39" at 145MHz), the sleeve is 19½" long and the driven element 20½".

2m Sleeve Dipole Antenna details
The ends are closed with plastic caps. A BNC socket is mounted on the sleeve end-cap and wired with RG-59/U coaxial cable. The centre conductor is soldered to the driven element and the braid to the sleeve. Care is taken to ensure that the BNC socket does not touch the sleeve.

A good weekend project, awaiting tests for effectiveness.

Related post: Wire Slim Jim for 2m
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