A Highly Selective HTS Bandpass Filter on Sapphire Substrate

Abstract

This paper presents a highly selective 24‐pole Chebyshev HTS bandpass filter. The filter was designed at 1748 MHz center frequency with 75 MHz bandwidth, which was suitable for the GSM base station. The filter was fabricated using double‐sided YBCO films on a 3 inch diameter, 0.43‐mm thick sapphire substrate. A novel resonator structure was proposed. The filter showed an excellent selectivity. At the band edge of the filter, the slope was about 17dB/MHz. Out of band the rejection level is better than −90 dB.