Low Cost/Insertion Loss Substrate-Integrated Waveguide Equalizer Based on Absorbing Materials

In this article, a new design method of substrate-integrated waveguide (SIW) equalizer is proposed. Different from the previous SIW equalizers using Tantalum Nitride (TaN) as the resistive element, the absorbing materials are introduced into SIW equalizer for the first time. The relationships between insertion losses and working frequencies, which is different from (Peng
et al.
, 2020), are all negative proportions. The equalizers in this work can be realized on the traditional printed circuit board (PCB) with lower cost and lower insertion loss (especially under larger equalizing values). The simulation results and measurement results show good agreements. The test results show that: over the entire
Ka
-band, the equalizing values are 2.94, 6.55, 9.74, 14.90, 20.39, and 24.01 dB, respectively, while the return losses are all better than −14.6 dB. Correspondingly, the insertion losses at the maximum frequency point (40 GHz) are only 2.32, 2.30, 2.77, 3.61, 4.60, and 5.34 dB, respectively. The ratios of insertion losses (RIL) at the minimum and maximum frequency point can be up to 2.27, 3.86, 4.52, 5.14, 5.43, and 5.56, respectively. The cost of SIW equalizer in this work, achieved on traditional PCB, is much lower than that of ceramic substrate in previous studies.