Phase shifter system using vector modulation for phased array radar applications

This work presents the design and implementation of a complete X-band phase shifter system using vector (polar) modulation, suitable for solid-state phased array radar applications, providing a cost effective solution which overcomes the main constraints involved with traditional systems. The performance characteristics for three intermediate frequencies (150MHz, 440MHz, 850MHz) are shown. The three cases present similar response. It was found that the errors were minimal for gain setpoints above -20dB providing a reliable dynamic range of about 20dB. The gain error is less than +/-1.5dB and the phase error is +/-17 degrees maximum. It can be observed that the lower the gain setpoint the higher the overall error, also the phase error is higher at phase setpoints near 0 and 180 degrees, likewise the gain error is higher at phase setpoints near +/-90 degrees.; The effect of the phase shifter's error in the main beam direction, beamwidth and side lobe level for a linear array is analyzed along a scanning angle of 90 degrees around broadside, using a 20 elements Chebyshev distribution. It is shown that designing for a desired SLL=-30dB, the main beam pointing direction error is almost negligible with a maximum beam deviation of 0.25 degrees. The side lobe level error is less than 5dB and the 3dB beamwidth error is lower than +/-0.2 degrees.; A four channel prototype was built to evaluate the network connectivity of the phase shifter and finally an X-band image reject mixer is added to verify its operation at X-band frequencies.