Microcontroller-based programmable phase shifter for array antenna system

This paper deals with the development of programmable phase shifter for array antenna system based on microcontroller. The array antennas in which their phases will be controlled are fed by the use of corporate feeding network. The shifting of phase for each antenna is carried out through variable capacitor (varactor) diode by changing its reverse bias voltage. Here, the microcontroller is employed to regulate the reverse bias voltage of varactor diode by controlling the output of pulse width modulation (PWM) signal. By using the optocoupler to isolate the PWM signal and the controlled voltage, equipped with the buck converter to obtain the regulated voltage for varactor diode without any external interference, the programmable phase shifter is optimized to shift the phase of each antenna independently. From the experimental result, it shows the realized prototype can produce the maximum phase shift of 85.243° and the minimum one of 0.37° at frequency of 2.4GHz.