A near-isotropic circulary polarized antenna for space vehicles

The theoretical design and experimental test of a simple, lightweight, and reliable circularly polarized omnidirectional antenna is reported. The gain for one sense of circular polarization, compared with isotropic, is more than -3 dB over 99 percent of the far-zone sphere. Good agreement between theory and experiment has been obtained. The antenna consists of a ring of crossed slots on a short-circuited cylindrical waveguide that is excited by two
TE_{11}
modes in phase and space quadrature.