    AN-SOF ANTENNA SIMULATOR
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This array consists of two resonant monopoles, each approximately 1/4 of a wavelength in height, and they are spaced by 1/4 of a wavelength. 

The simple feed system comprises two 75 Ohm transmission lines. One end of each transmission line is connected to a common voltage source, while the other end is connected to a monopole base. 

To achieve a relative phasing of 90 between the two vertical elements, one of them is fed with a line that is 90 electrical degrees longer than the other. When calculating the electrical lengths and phase differences, please consider that the velocity factor of the transmission lines is 0.66. 

This configuration results in a cardioid radiation pattern. However, the maximum radiation direction is not at ground level, but at a zenith angle of theta = 65 (or 25 of elevation). 

This array and simple feed system represent the simplest method to obtain a directional radiation pattern with a cardioid shape.
