Inventors:
Krishna Pande - Gaithersburg MD 20878
Guobao Zheng - Oakhill VA 20171
Tho Nguyen - Chantilly VA 20151
Lee Phelps - Frederick MD 21702
Ali I. Bawangaonwala - Germantown MD 20874
Sunil M. Nagabhushana - Centreville VA 20121
Eric Funk - Annapolis MD 21401
International Classification:
H04H 100
US Classification:
455 301, 455 76, 455 81, 361688, 361704
Abstract:
The complete outdoor radio unit for LMDS is a light weight, compact transceiver featuring planar circuitry. The transceiver uses cross polarization through an orthomodal transducer and frequency offset between transmit and receive to provide isolation between the transmitter and receiver. The transceiver includes three printed circuit boards directly attached by thermally conductive epoxy to a heat sink which forms part of the antenna dish/transceiver housing for effective heat transfer. Two of the waveguides are used as receiver and transmitter transmission lines into the orthomodal transducer, and two of the waveguides are used as bandpass filters. The transceiver also includes a DCâDC converter in the power supply which is modified to connect the base plate to the heat sink for compactness and improved heat transfer, and a frequency synthesizer with a phase locked loop hardwired to a single reference frequency for compact size.