A Frequency Independently Tunable Dual-Band Bandpass Filter With Large Frequency Ratio and Ultra-Wide Stopband

A dual‐band filtering crossover with large frequency ratio for microwave and millimeter‐wave applications

“…This is insufficient for the emerging 5G applications, which require to support microwave and millimeter-wave bands simultaneously. [19][20][21] In those cases, dual-band components with a frequency ratio larger than 10 are usually required. However, to the best of our knowledge, no dual-band crossover with a frequency ratio larger than 10 has been reported in the literature.…”

“…To implement such a large frequency ratio, a microstrip filtering crossover operating at microwave band and an SIW filtering crossover operating at millimeter-wave band are combined through the aperture coupling mechanism. 20,21 As the two elements almost have no influence on each other, a high degree of design freedom over two bands can be obtained. For demonstration, a dual-band filtering crossover operating at 2.4 and 28 GHz was designed, fabricated, and measured.…”

“…However, all these structures, 10–18 no matter with or without filtering characteristics, can only provide a frequency ratio smaller than 5. This is insufficient for the emerging 5G applications, which require to support microwave and millimeter‐wave bands simultaneously 19–21 . In those cases, dual‐band components with a frequency ratio larger than 10 are usually required.…”

“…Dual-band filtering crossover with a large frequency ratioTo combine the microstrip and SIW filtering crossovers, a dual-band feeding structure based on the aperture coupling mechanism20,21 is utilized. The configuration and layout of the dual-band feeding structure are shown in Figure3A,B, respectively.…”

Dual-Narrowband/Wideband Filters Using Modified Coaxial Cavities With Large Frequency Ratios

“…Recently, dual-band planar filters with a large frequency ratio based on the complementary frequency response characteristics of the stepped-impedance resonator bandpass filter and low-pass filter [1] and mode composite coplanar waveguide [2] have been proposed. In addition, a tunable dual-band filter with a large frequency ratio, combining a microstrip bandpass filter and a dielectricloaded bandpass filter, has been proposed in [3]. However, these structures are difficult to apply to the base transceiver stations.…”