This is my favorite antenna for mobile transmitter hunts, as it doesn’t stick up as high above the roof as a yagi (for vertical polarization). A 3-element version has better performance, but is harder to turn at speed due to to the added wind drag.
At some point I’ll get better instructions with photos added here, but for the moment you can follow this link to a text description. (Sorry, the dimensions are only given in Imperial units.)
An older version, showing construction detail. This uses a bent-wire gamma match (upper right element), which is easy to adjust, but causes the polarization to rotate about 45 degrees. Newer versions use slightly different dimensions and are fed through a quarter wavelength of 75 coax instead.2-element quad mounted on the car. The boom can be rotated for either vertical or horizontal polarization.Using a junction block to feed the quad. The element wires pass through the spreader and then into the connections on the left, which helps to hold them in place. The coax connects on the right.
