Novel solutions to low-frequency problems with geometrically designed beam-waveguide systems

Abstract

The poor low-frequency performance of geometrically designed beam-waveguide (BWG) antennas is shown to be caused by the diffraction phase centers being far from the geometrical optics mirror focus, resulting in substantial spillover and defocusing loss. Two novel solutions are proposed: (1) reposition the mirrors to focus low frequencies and redesign the high frequencies to utilize the new mirror positions and (2) redesign the input feed system to provide an optimum solution for the low frequency. A novel use of the conjugate phase-matching technique is utilized to design the optimum low-frequency feed system, and the new feed system has been implemented in the JPL research and development BWG as part of a dual S-/X-band (2.3-GHz/8.45-GHz) feed system. The new S-band feed system is shown to perform significantly better than the original geometrically designed system.

Full-wave consistent MDS-based simulation of a beam-waveguide circuit fragment for a deep space communication or radio astronomy antenna

“…The considered geometry concept is based on the first four elements of both ESA-ECOS and NASA-JPL Goldstone's deep space communication facility feeding circuits [12], [13]. It consists of a flat mirror M1 with the size of d 1 = 11λ, an elliptic-arc fragment E1 (d 2 = 21λ), another flat mirror M2 (d 3 = 13λ) and an offset parabolic reflector P1 (d 4 = 20λ).…”

Combining microwave beams with high peak power and long pulse duration

“…Therefore, the key element for the beam combining system is the dichroic plate. Dichroic plates have been used widely for low power applications, such as deep space missions, 16,17 among others. However, the output microwave beams of modern HPM sources usually have powers of GW level and unstable phases and frequencies.…”