5/8 Wave or 5/8 Colinear

Here is an easy to build and rather weather proof 2 meter amateur radio antenna.

The most important formula: x =300/fMhz (x is expressed in meters here - to get inches multply by 39.37") that a Homebrew Amateur Antenna Constructor could ever learn.


x"=49.386" for 142 Mhz
x"=48.7" for 144 Mhz
x"=48.033" for 146 Mhz
x"=47.384" for 148 Mhz
x"=46.752" for 150 Mhz

x" x 1/2" dia. rigid copper pipe.
3/4" PVC pipe encases the whole antenna.

20" Encased Coil - 70-74 turns wound on a 1/4" dia. wooden or simular material pole. #14 gauge solid copper wire no insulation. Solder each end to the inside of its respective copper pipe.

Feed Coil - Is 2" long and consists of 4 turns of #14 gauge bare copper wire wound on outside of 3/4" PVC encasement pipe. The upper end of which attaches to x" rigid copper pipe. thru 6-32x1 1/2" screw which is put thru 3/4" PVC and 1/2" x x" rigid copper pipe (hole slightly smaller than clearance this allows you to thread hole with 6-32x1 1/2" screw to make electrical contact). The lower end attaches to 6-32x1 1/2" screw which passes thru 1" x 36" aluminium pipe, 3/4" PVC encasement pipe, and 1/2" x 39" PVC filler pipe.

Coax attachment - Braid attaches to 6-32x1 1/2" screw at base of feed coil. Center of coax is soldered to second turn up from base of feed coil or center of 4 turn coil.

Base consists of 1/2"x39" PVC filler pipe inside of 3/4" encasement PVC outside of which is 1"x36" aluminium groundplane pipe.

1 piece 3/8"x72" solid aluminium rod used for radials. Divide it into 3 - 24" pieces bend each piece so it look like diagram below.

Slip the 4" portion of each into the 2- 1 1/2" hose clamps shown on the 1"x36" aluminium pipe on the bottom of the antenna the radials should be slid up as close to the matching coil as possible without touching same. Tighten hose clamps spread out the radials equal distance around 1" aluminium pipe roughly 120°.

Mounting can be done in two ways simply slip base of antenna into 1 1/4" mast mounted in tripod or at top of tower or use 1/4" thick 8"x4" aluminium plate and 4 U-clamps 2- 1 3/8" and 2- 1 1/2" drillled thru it. 2- 1 3/8" U-clamps hold aluminium plate to antenna. 2- 1 1/2" U-clamps hold aluminium palte to mast.

Secure coax to mast with electrical tape. Open coax end, 2- 6-32x1 1/2" screws, and 4 turn x 2" coil are all encased in clear RTV sealant.(silicon sealant)