Microwave Beamformer Receiver Front End

Abstract

Telecommunication industry has always competed against limited resources and increasing number of users. Smart Antennas are now becoming attractive tool as they reduce the interference and maximize the bandwidth utilization. Smart antennas have, in recent times, received considerable attention for their use in communications, electronic surveillance and electronic countermeasures where it is advantageous to have a single antenna that can dynamically steer the beam to the desired angle to transmit or receive the signals. The report includes the design and analysis of a Microwave Sampling Beamformer with beam steering capability. A Microwave Sampling Beamformer consisting of four patch antennas has been developed and tested. The project consists of RF hardware, microwave hardware and control circuitry. Agilent ADS software has been used as a design tool. PIN diodes have been used as phase shifters in the design. A novel phase shifting switch design has been implemented in the structure. The control circuitry consists of four pulse generators driven by the same oscillator. PIN diode drivers have been designed to provide appropriate biasing conditions and to ensure impedance matching between the pulse generators and the diodes. The microwave part includes RF amplifier, frequency down-converting mixer, Intermediate Frequency amplifier and low pass filter. The phase shift for each of the four patch antennas is controlled through the time delay of the corresponding pulse train. The measured results show that the structure is capable of steering the beam in the range of ±45 degrees. The structure has been designed and tested to operate at a frequency of 5.8 GHz.