L band multi-channel transmit/receive module for circular phased array radar

This paper presents the design and development of a high power, multichannel L band (1.2-1.4 GHz) Transmit/Receive (T/R) module. The motivation behind this development is to have the ability to gain fast electronic beam switching at the elevation plane and antenna switching at the azimuth plane by employing non-rotating circular phased array antenna architecture. 25W peak output power with a pulse width up to 100 usec at a duty of %50 is achieved at each channel of the transmit/receive module by designing class F GaN RF power amplifier. GaN HEMT is chosen as the RF power transistor to take advantage of its high efficiency, ruggedness and thermal stability features. The efficiency of %75 is obtained at the amplifier output with larger than 50 dB harmonic rejection. Cooling of the high power module is provided by conduction and natural convection mechanisms. Inter pulse waveform stability figure of 65 dB and inter channel average group delay distortion of 0.25 nsec is achieved which satisfies successful phased array radar operation.