High power added efficiency half mode substrate integrated waveguide power amplifier with the second harmonic suppressed

In this paper, for the first time a novel 10W half mode substrate integrated waveguide (HMSIW) power amplifier (PA) with high power added efficiency (PAE) is presented. The matching network (MN) of the HMSIW PA is designed with microstrip-to-HMSIW transition and HMSIW bandpass filter. The HMSIW bandpass filter is employed in both input and output MNs to suppress the 2^nd harmonic of 2.14 GHz, according to the measurement, the insertion loss of the HMSIW bandpass filter at 4.28 GHz is 36.1 dB while at 2.14 GHz is 0.5 dB. The impedance matching for the fundamental frequency 2.14 GHz is realized by adding one inductive metalized post in the HMSIW bandpass filter. One high PAE HMSIW-based 10W PA using GaN HEMT at 2.14 GHz is designed, fabricated, and measured. Measured results show that the maximum PAE is 71.9 % with 41.4 dBm output power and the maximum gain is 16.9 dB. At the design frequency of 2.14 GHz, the size of the proposed HMSIW-based PA is comparable with other microstrip-based PAs.