Substrate Integrated Waveguide Equalizers and Attenuators With Surface Resistance

In order to compensate for amplitude inconsistencies of components and circuits, the equalizer has been proposed and introduced. In the previous reports, the theory of equalizer is mainly based on the resonant circuit. In this article, the substrate integrated waveguide (SIW) equalizer fabricated on a ceramic substrate with surface resistance, operating in a millimeter- wave band, is presented first. The key point for SIW equalizer is the introduction of surface resistance instead of the copper layer in a particular location. The working principle of SIW equalizer is discussed in detail. Then, the design method and the procedure are given and demonstrated. A good agreement between the measurement and the simulation indicates its excellent performances. For measurement results, the return losses are better than -18.8 dB for the SIW equalizing values of 2.8, 5.6, and 9 dB over the whole Ka-band. Based on the previous analysis of SIW equalizer, an extensible application in SIW attenuator operating in a millimeter- wave band has been presented first. Measurement results show that the attenuation levels of 5.45 +/- 0.15, 10.6 +/- 0.4, 21 +/- 1, and 30.75 +/- 1.45 dB have been achieved in a band of 24.8-38.4 GHz. Besides, the return losses are better than -20 dB in the same frequency band.