This guide explains how to run a script in Scilab to simulate a 3-element Yagi-Uda antenna and get the results as a function of the spacing between the elements. A second script allows us to plot the antenna gain versus element spacing.
2-element quad antennas are very popular due to their compact size and gain similar to a more element Yagi. In addition, they can be designed to obtain an input impedance of 50 Ohm. This design can operate at 27.5 MHz.