Abstract
A novel dualband high-temperature superconducting (HTS) bandpass filter is proposed with group delay equalization for 5G emergency communication receivers with N41 and N79 bands in this paper. The dual-folded stub-loaded stepped impedance resonator (DSLSIR) is applied to realize dualband performance. The proposed DSLSIR has miniaturized circuit size and more design freedom to independently adjust the two designed center frequencies, comparing with other reported DSLSIRs. Two cross-coupling transmission lines are added at the top and bottom parts of the cascaded sixth-order filter with DSLSIRs to flatten the group delay of the passband at both bands. A dualband bandpass HTS filter etched on the YBCO superconducting material is fabricated to verify the proposed design method. The measurement is actualized at the temperature of 77 K to make YBCO microstrip lines perform superconducting features. The results show that the first center frequency is 2.595 GHz with 6.2% bandwidth for N41 band and 0.3 dB insertion loss while the second center frequency is 4.85 GHz with 2% bandwidth for N79 band and 0.4 dB insertion loss. Meanwhile, the group delays at the N41 and N79 bands keep 2 ns fluctuations in the 60% passband. The agreement between the measured and simulated results indicates that the proposed dualband bandpass HTS filter with low insertion loss, sharp roll-off skirt and flat group delay is a promising candidate for emergency communication receiver.
Highlights
Emergency communications in catastrophic situations, such as forest fires, floods, landslides, mudslides and earthquakes, have crucial requirements of the radio frequency receiver on the sensitivity and roll-off rate for better signal covering range
Most of the multi-band bandpass high-temperature superconducting (HTS) filters are based on the modified stub-loaded resonator and modified stepped-impedance resonator
The equivalent circuit model of the proposed dual-folded stub-loaded stepped impedance resonator (DSLSIR) is displayed in Fig. 1(a), which consists of two parts: the symmetrical SIR part and the open stub part
Summary
Emergency communications in catastrophic situations, such as forest fires, floods, landslides, mudslides and earthquakes, have crucial requirements of the radio frequency receiver on the sensitivity and roll-off rate for better signal covering range. Most of the multi-band bandpass HTS filters are based on the modified stub-loaded resonator and modified stepped-impedance resonator. Both of them can be applied to adjust working. Yang et al.: Dualband Bandpass HTS Filter with Group Delay Equalization bandwidths and transmission zeros separately of the designed bands simultaneously [7]–[12] All of these multiband bandpass HTS filters as mentioned earlier have low insertion loss and sharp roll-off skirts. An experiment based on the proposed design method is implemented and the measured results prove its effectiveness This is the first reported dualband bandpass HTS filter with dualband group delay equalization to the best of our knowledge
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