Simultaneous Electric and Magnetic Two-Dimensionally Tuned Parameter-Agile SIW Devices

Abstract

A concept of simultaneous electric ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> ) and magnetic ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> ) 2-D tuning is presented, demonstrated, and applied for the first time through the theoretical and experimental studies of parameter-agile substrated integrated waveguide (SIW) devices. First of all, a two-dimensionally tuned SIW cavity is introduced as a building block. Considering only electric tuning with varactor diodes, no more than 1.3% of total tuning range is accomplished, while for simultaneous electric and magnetic tuning, it is extended to 7.9% with an unloaded <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> factor of better than 130. Using 0.05-0.1-pF surface mount capacitors, a total tuning range of as much as 20% is experimentally achieved at 12 GHz. Another characteristic of significant interest is that the proposed 2-D tuning not only allows changing frequency, but also simultaneously optimizing other key parameters such as the return loss or unloaded <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> factor. Second, the dual-tuned SIW cavity resonator is further accommodated to demonstrate parameter agile two-dimensionally tuned bandpass filter at 12 GHz. The proposed concept of 2-D tuning theoretically and experimentally demonstrates a simultaneous frequency and bandwidth tuning of bandpass filter. This filter can perform both frequency-tunable constant bandwidth, and constant-frequency variable-bandwidth operations. Third, a cavity backed slot antenna using the proposed dual tuning is demonstrated. The tuning not only achieves a higher frequency range, but the antenna return loss is optimized to improve the overall efficiency.