High Isolation Substrate Integrated Waveguide Diplexer With Flexible Transmission Zeros

Abstract

This letter presents a high isolation substrate integrated waveguide (SIW) diplexer using dual-mode resonators. Each dual-mode SIW resonator can generate one transmission pole (TP) and one transmission zero (TZ) for the channel filter. The frequencies of the TZs can be easily controlled by the perturbation vias. One channel filter's two TZs' frequencies are designed to cover the other channel filter's passband. Thus, high isolation performance is achieved. The proposed diplexer is designed and fabricated with lower and upper channels centered at 8.04 and 9.07 GHz, respectively. Simulated and measured results are in good agreement for the two channels with better than 49/53 dB channel isolation.

Substrate Integrated Waveguide Multiband Bandpass Filters and Multiplexers: Current Status and Future Outlook

“…6. As can be seen, various matching networks can be exploited and combined with diverse SIW single-band BPFs to develop SIW multiband BPFs and multiplexers based on this scheme, embracing multiport wideband T-junctions based on SIW [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38] or microstrip [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53] technologies, circulators [31], manifolds [32], coupling apertures [54], [55], switches [56], shared feeding ports [57],…”

Implementation of a Highly Selective Microstrip Diplexer with Low Insertion Loss Using Square Open-Loop Resonators and a T-Junction Combiner

“…Except for [2], which has a frequency space ratio R = 0.1, the proposed fabricated diplexer has the smallest FBWs of 2.23% and 2.98% (best selectivity) and the smallest frequency space ratio R = 0.105 so far. Furthermore, when compared to [2,4,6,8,9,10,11], the manufactured diplexer has the lowest insertion losses of IL = 1.25 dB / 1.22 dB and the greatest isolations of 48.99 dB / 57.02 dB at the measured frequencies f t = 1.801 GHz and f r = 2.001 GHz, respectively, with the exception of [10], which has the lowest insertion losses of 0.4 dB / 0.5 dB. In terms of fractional bandwidth, inser- tion loss, and isolation characteristics, the proposed manufactured diplexer surpasses the competition.…”

Efficient Diplexer With High Selectivity and Low Insertion Loss Based on Solr and DGS for Wimax

“…Nerveless, the multilayer structure complicates the circuit integration and processing. In [10], a substrate-integrated-waveguide (SIW) based diplexer of high isolation using dual mode resonators has been introduced; however, it still suffers from large size and high insertion loss. Recently, defected ground structures (DGS) have been developed to enhance the properties of various microwave devices, including filters [11], duplexers [12], couplers [13], and antennas [14].…”