Computer controlled gain adjustable microwave amplifier design and analysis of the prototype application results

Studies in the field of microwave technology are important in many applications, especially in communication systems. Adjustable-gain microwave amplifier designs are frequently used in antenna array systems. In this study, a microwave amplifier whose gain can be adjusted digitally was designed and realized as a prototype. Employing the SPF5189Z as the monolithic microwave integrated circuit (MMIC), an amplifier design operating in the 50 Hz - 4000 MHz range, whose gain can be adjusted by computer control, has been realized. The designed microwave amplifier system was first installed on a breadboard. After verifying that the circuit works properly, PCB drawings were made and prototype production stages were completed with a circuit scraping machine. Different PWM values that change the supply voltage between 0.58 and 1.78 volts were applied under computer control for the implemented microwave amplifier system and then the S-parameters of the amplifier were measured with a vector network analyzer (VNA). According to the measurement results, a microwave amplifier design with gain adjustment between -2.31 dB and 9.02 dB at 2.4 GHz frequency was obtained.