Controllable Phase Shifters for dynamically Steerable Antennas

The following thesis is Steerable Antenna focused on the phase shifter part for GNSS application which working from 1.55 GHz to 1.57 GHz. The purpose of this thesis is to design an Analog Phase Shifter with the capability of phase shifting in 360◦and a low return loss ratio. In this thesis, a quadratic hybrid branch line is used as the main part. The key component of the phase shifter is the Varactor Diode which its Capacitor value is varying by changing DC voltage which I used two of it. It works from 0 V to 5 V and its capacitance value is change in 12 different values. To prevent the effects of the DC voltage on the RF signal in the input and output, two Interdigital Capacitors are located on the input and output port. On the other hand, a low pass filter is connected to the quadratic hybrid branch line to block the RF signal path to the DC port. Moreover, for covering more phases, I have used 4 lines with 0◦, 90◦, 180◦, and 270◦electric lengths respectively. To pass the signal through each line, two switches are placed at the output of the Analog Phase Shifter and the end of the lines. The substrate is I-Tera with epsilon= 3.45andits thickness is 0.250 mm. Moreover, the conductor is copper with a thickness equal to 18μmBy this structure, the input RF signal is phased shifting in 48 different degrees (4lines and each line has 12 phases). The return loss of the Analog Phase Shifter for all the phases is below -15 dB in the frequency range. The Analog Phase Shifter is a low-cost phase shifter concerning the other types. Also in this thesis, it is tried to reduce the size of the Phase Shifter and decrease radiation loss.