Miniaturized High-Performance Cube-Shaped Filter Made Up of Quasi-TM₀₁₀ Mode Dielectric-Loaded Cavities

Abstract

In this paper, a compact quasi-TM 010 mode dielectric-loaded bandpass filter with 8th-order pseudoelliptic filtering function and symmetric positioning of 4 transmission zeros is analyzed and designed. The resonant frequency and field components of quasi-TM 010 mode of a cylindrical dielectric resonator (DR) were first calculated and simulated. Compared to the pure TM 010 mode, the unloaded Q factor of quasi-TM 010 mode can increase by 3000 to more than 8000 and then the dimensions of the single DR at 2.595GHz are π ×34 2 ×20 mm 3 (using ε r = 45). The magnetic coupling and electric coupling between dielectric-loaded cavities are studied and the dielectric window is innovatively proposed to generate electric coupling and to avoid the use of metallic probes that are cumbersome to assemble. In final, a quasi-TM 010 mode doublelayer filter with two pairs of symmetric transmission zeros is designed according to the cubic-like topology and fabricated and tested which exhibits close agreements between the simulated and measured results demonstrating the advantages of low insertion loss, very close-to-band rejections and compact configuration. The proposed filter has great potential for development in 5G mobile communication systems and microwave radar communication systems. INDEX TERMS Quasi-TM 010 mode, dielectric resonator, dielectric filter, elliptic filter, transmission zeros.

A dielectric resonator bandpass filter using printed circuit board technology for wideband application

“…The first technology as shown in Figure 1A is using individual dielectric ceramic as resonator loaded in the metallic cavity to realize single-ended bandpass filter [9][10][11][12][13] and balanced bandpass filter, [14][15][16] which is difficult to integrate with other planar circuits. For easily integrating with other planar circuits, the second technology as shown in Figure 1B [17][18][19][20] using individual dielectric ceramic as resonator mounted on the low dielectric constant substrate in the metallic cavity is proposed.…”