A Ka-band circularly polarized high-gain microstrip array

Presents a circularly polarized microstrip planar array that resonates at 32 GHz and provides a broadside beam, a minimum gain of 28 dB, and a bandwidth greater than 1 GHz. This low profile, small mass antenna is to be surface mounted on a microspacecraft that is being developed for future, deep space, NASA missions. Challenges arising from the development of this Ka-band antenna include the minimization of the array´s feed network loss and the attainment of the required bandwidth. High-gain microstrip arrays that have previously been developed for Ka-band or higher frequencies have primarily been linearly polarized (l.p.). In the case of this array, circular polarization (c.p.) is achieved by employing the sequential rotation technique in which each patch element is excited at a single feed point. This technique is employed to minimize the insertion loss that occurs in the microstrip transmission line feed network and to satisfy the array bandwidth requirement. To further reduce the insertion loss, the feed network uses a combined parallel and series feed technique. By designing the microstrip line feed network with matched impedances throughout the entire circuit, the bandwidth performance is further enhanced.<>