Omnidirectional Square Loop Segmented Antenna

A square loop antenna of circumference about one free-space wavelength displays an omnidirectional radiation pattern when its conductor is partitioned into five segments that are interconnected by four small capacitances. The optimization process for determining the capacitances values is described in detail. The required four capacitances are created by overlapping the conductor segments on the opposite sides of the substrate. The far field of the antenna resembles the one of an elementary magnetic dipole. At the center frequency of 956 MHz, the measured maximum gain is 2 dBi, and the measured antenna efficiency is 94%.