All you need to build a simple VHF or UHF 1/4 wave groundplane antenna is a coax chassis connector and number 12 or larger wire scraps. Solder the vertical element to the center conductor and attach the radials with nuts and bolts to the four corners, then solder each corner.
Make the vertical element a bit longer than calculated and bend the radials down 25 to 30 degrees a short distance from the connector flange. Then trim the vertical element (in small increments) for the minimum SWR at the low end of the band in which it will be used. When the SWR begins to go back up, it should be lowest near the center of the band. If not, trim carefully until it is. Then little by little bend the radials down until you get a 1 to 1 SWR. This will be between 30 to 45 degrees, as shown below.
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