Here's a simple broadband yagi antenna that can be built on a 4 foot boom and used for portable ATV, SSB, or satellite work on the 70-cm band. It's a scaled down version of the 144 MHz ultra wideband yagi produced by Rutland Arrays. The antenna design was optimized for broadband performance using YAGIMAX software.
The antenna should be built on a non-conducting boom, such as a wooden ferring strip or dowel. The elements are #10 solid copper wire (with insulation removed). The driven element is matched to a 50 ohm unbalanced feed using a `T' match and a half wavelength coaxial balun.
Approximate dimensions of the driven element and delta match that provide a low SWR across the lower portion of the 70-cm band. Multiply dimensions by 2.54 to obtain lengths in centimeters. Balanced feed is obtained across the 0.5 inch gap in the lower portion of the delta match.
Actual antenna performance closely matches the computer simulation shown here.