A Compact Metamaterial-Based Tri-band Microwave Power Amplifier Using Substrate Integrated Waveguides and Complementary Split Ring Resonators

This paper presents a tri-band microwave power amplifier (PA) that uses a substrate integrated waveguide (SIW) loaded with a complementary split ring resonator (CSRR) to realize a compactness by employing an evanescent mode operation. The proposed PA operates concurrently at three operation frequencies—6 GHz, 8 GHz, and 10 GHz. The measured performance of the PA at 6 GHz exhibited an output power of 36.57 dBm, a large-signal gain of 11.4 dB, and a power added efficiency of 52.2%, while these parameters at 8 GHz and 10 GHz were 35.51 dBm and 34.57 dBm, 11.3 dB and 6.1 dB, and 47.2% and 30.3%, respectively. For linearity evaluation, the designed PA was tested using a 16-Mbps Quadrature Phase Shift Keying (QPSK)-modulated signal. The results exhibited an adjacent channel power ratio better than -35 dBc and an output power of 32 dBm at 6 GHz, 8 GHz, and 10 GHz. Notably, the final printed circuit board (PCB) occupied a compact board size of 6 cm × 8 cm. Moreover, the simulations accurately predicted the measurements, thus validating the effectiveness of the proposed methodology.