Substrate integrated waveguide predistorted filter at 20 GHz

This work presents the synthesis, design and testing of a fourth-order Chebyshev predistorted filter centred at 20 GHz and with 300 MHz bandwidth, implemented in substrate integrated waveguide (SIW) technology. Although the dielectric material adopted in this work allows for obtaining SIW resonators with a quality factor Q=500, the use of predistortion permits to realise a filter response with an in-band flatness equivalent to a filter with Q=2000, not achievable otherwise with the adopted material in SIW technology. Additionally, this work presents the design and testing of a conventional SIW filter (without predistortion) implemented with the same dielectric material. Comparison of the measured filter responses demonstrates the benefits of using predistortion technique in SIW technology for achieving improved performance at high frequency.