Griffin K. Gothard

Design of a Simultaneous Center-Fed X/Ka-Band SATCOM Reflector Antenna with Replacable C-Band Option

A 1.5m tri-band (C-, X- and Ka-band) center-fed SAT-COM terminal has been designed for shipboard applications. The terminal has two independent replaceable feeds; C-band and simultaneous X/Ka-band. Offset prime-focus and dual-reflector designs are optimum from a performance standpoint for a reflector of this electrical size, however the scarcity of real estate and other mechanical considerations on shipboard drives the design to a center-fed type. Of the available center-fed reflector types, a shaped ring-focus configuration was chosen since the ring-focus reflector has several advantages over Cassegrain/Gregorian types for reflectors in this electrical size range. The reflector antenna shape is derived numerically utilizing GO shaping techniques while the feeds are designed using the BOR MoM and PO methods. The resulting antenna has been constructed and tested, and results are presented.

A center fed multi-band antenna for simultaneous satellite communication at C and Ku bands

As the Navy requires increased data throughput via satellite communications at sea, the need for a vessel based SATCOM multi-band antenna operating at both C and Ku-bands is on the rise. The design of a compact, high performance, simultaneous C and Ku-band antenna and feed presents many technical challenges. Such challenges include mechanical packaging of the feed components with short focal length optics, broadband axial ratio that is less than 0.75 dB, and broadband high efficiency. This paper describes the design and testing of a multi-band coaxial antenna subsystem as part of the Navy Commercial Broadband Satellite Program (CBSP). The subsystem includes capability to switch among linear and circular polarization at C-band as well as adjustable linear polarization at Ku-band. Both software simulations and test data are presented for the antenna performance.