Sunil M Nagabhushana

US Patent:

20020065052, May 30, 2002

Filed:

Nov 29, 2000

Appl. No.:

09/725240

Inventors:

Krishna Pande - Gaithersburg MD, US
Guobao Zheng - Oakhill VA, US
Tho Nguyen - Chantilly VA, US
Lee Phelps - Frederick MD, US
Ali Bawangaonwala - Germantown MD, US
Sunil Nagabhushana - Centreville VA, US
Eric Funk - Annapolis MD, US

International Classification:

H04H001/00

US Classification:

455/067500, 455/003020, 455/082000, 361/688000

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 offeset beteen 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. One of the three circuit boards is a millimeter wave circuit board, which is attached to the heat sink by a millimeter ground plane. The millimeter ground plane has a plurality of cavities defined therein which form the lower portion of waveguide assemblies. 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 waveguides interface with the millimeter wave board through microstrips. The millimeter wave board is connected to the other circuit boards by a flex cable using thin film conductive strips to accommodate both high frequency and DC voltages. The transceiver also includes a DC-DC 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.