Sai-Wai Wong

Wideband Bandpass Filter Using U-Slotted Substrate Integrated Waveguide (SIW) Cavities

A wideband fifth-order bandpass filter (BPF) is proposed and designed using the U-slotted substrate integrated waveguide (SIW) cavities. The U-shape slots, etched on the SIW cavity, are used to form up a new multiple-mode resonator (MMR) in order to achieve a wide passband of operation while keeping the overall size of the filter circuit to be much compact. The proposed fifth-order SIW filter is 2.5 times in size reduction compared with the traditional fifth-order SIW filters using the single-mode SIW cavities. In order to prove the validity, one wideband SIW BPF on a single layer printed circuit board (PCB) is designed and experimentally examined. The measured results show that the filter achieves an insertion loss of 1.1 dB at 8.5 GHz, return loss of higher than 11 dB and 3 dB fractional bandwidth of 42%. The measured results are in good agreement with the simulated results.

Triple-Mode Dielectric Resonator Diplexer for Base-Station Applications

This paper proposes a novel diplexer based on triple-mode dielectric-loaded cylindrical cavities. Such two metal cavities are designed to achieve two different frequency bands, while three resonant modes of a single cavity are classified as a TM mode and a pair of hybrid (HE) degeneration modes. An off-centered dielectric resonator instead of a traditional corner cuts perturbation or screws perturbation properly perturbs the two degenerate modes in the same cavity. Extensive study is then conducted to design this proposed diplexer. Finally, a diplexer prototype is fabricated using a brass cavity and it is tested for experimental verification of the predicted results. Good agreement between measurement and simulation is achieved.

Triple- and Quadruple-Mode Wideband Bandpass Filter Using Simple Perturbation in Single Metal Cavity

This paper proposes a novel class of wideband metal cavity multiple-mode bandpass filters (BPFs), consisting of a triple-mode filter and a quadruple-mode filter. Two TE11 degeneration modes in a single metal cavity are excited by using an off-centered approach instead of a traditional corner-cut approach. They work together with the TM10 mode to constitute a three-pole wide passband with a fractional bandwidth of 30% at the central frequency of 3.2 GHz. Moreover, an off-centered metal cylinder can properly excite an extra TM11 mode in the passband. As such, this TM11 mode, TM10 mode, and a pair of degeneration TE11 modes can be simultaneously utilized to form a quadruple-mode BPF. Compared with the triple-mode BPF, the quadruple-mode BPF has better performance in term of the steepness of rejection skirt. The fractional bandwidth of this BPF can achieve up to 31%. In final, the two proposed BPFs are fabricated by using the silver plated aluminum technology. Measured S-parameter frequency response and group delay have satisfactorily matched with the simulated results.

Dual-Band Coaxial Cavity Bandpass Filter With Helical Feeding Structure and Mixed Coupling

In this letter, stepped-impedance resonators are used in coaxial cavity filter to generate dual-band response. Two key merits of the proposed filter are the helical feeding structure and the introduction of mixed coupling for coupling control and generation of transmission zero. The helical feeding structure makes it possible to conveniently control the external quality factors of two bands. To illustrate the concept, a third-order dual-band coaxial cavity filter is designed, fabricated and measured. The measured results are in good agreement with the full-wave simulation results.

U-Shape Slots Structure on Substrate Integrated Waveguide for 40-GHz Bandpass Filter Using LTCC Technology

Millimeter-wave (mmW) bandpass filter using substrate integrated waveguide (SIW) is proposed in this paper. The propagation constants of three different types of electromagnetic bandgap (EBG) units are discussed and compared with their passbands and stopbands performance. The slotted-SIW unit shows a very good lower stopband and upper stopband performance. The mmW bandpass filter with three cascaded uniform slotted-SIW-based EBG units is constructed and designed at 40 GHz. The extracted coupling coefficient (K) and quality factor (Q) are used to determine the filter circuit dimensions. To prove the validity, the previous proposed structure is fabricated in a single circuit layer using low-temperature co-fired ceramic technology and measured at 40 GHz, respectively. The measured results are in good agreement with simulated results in such frequency and the measured insertion losses at 40 GHz is 1.42 dB, respectively.

Compact Reflection-Type Phaser Using Quarter-Wavelength Transmission Line Resonators

A compact reflection-type phaser composed of quarter-wavelength transmission line resonators interconnected by alternating K- and J-inverters is proposed. A design method is also presented. To validate this method, a fourth-order example is designed and fabricated. The proposed phaser is shown to exhibit the benefits of smaller size, easier fabrication and suppressed even-order harmonics compared with previously reported half-wavelength phasers.

Triple-Mode Dielectric-Loaded Cylindrical Cavity Diplexer Using Novel Packaging Technique for LTE Base-Station Applications

This paper proposes a triple-mode dielectric-loaded cylindrical cavity diplexer by using a novel packaging technique for long term evolution (LTE) base station applications. Four metal cavities, loaded by a triple-mode dielectric resonator (DR), are designed to resonate at two different frequencies for the diplexer operation. In this context, three resonant modes of a single cavity are classified as a TM mode and a pair of hybrid degenerate modes (HE modes). The two degenerate modes in the same cavity are properly excited by employing an off-centered DR instead of a traditional corner-cut structure as a perturbation element. Finally, such a diplexer is designed and fabricated, and good agreement between measurement and simulation is achieved.

Synthesis Method for Substrate-Integrated Waveguide Bandpass Filter With Even-Order Chebyshev Response

A synthesis method for an even-order Chebyshev bandpass filter of a substrate-integrated waveguide (SIW) is proposed in this paper. The transformation of a Chebyshev polynomial is studied and applied to achieve an equal source and load termination for an even-order filtering response. This transformed Chebyshev polynomial is used to design a millimeterwave (mmW) SIW bandpass filter through electric coupling of SIW resonators or cavities. The cascaded resonators are formed by properly etching the slots on the top metal plane of a single SIW cavity, and these slots create electric coupling as desired in a filter design. The proposed synthesis procedure of coupled-resonator bandpass filter with an even-order Chebyshev response is given and discussed here in detail. The theoretical and extracted external quality factor (QE) and coupling coefficient (K) are utilized to determine the filter circuit dimensions. Two fourth-order bandpass filters are designed at 140 GHz under a Chebyshev response using magnetic coupling and electric coupling as design examples. These two filters are used to prove the correctness of the proposed synthesis method as well as the advantages of electric coupling in mmW. In order to prove the validity, the previously proposed fourth-order filter using electric coupling is fabricated. The filter is fabricated in a single substrate layer using a low-temperature cofired ceramic technology and measured in a frequency band around 140 GHz. The measured results are in good agreement with simulated results.

A Triple-mode Wideband Bandpass Filter Using Single Rectangular Waveguide Cavity

A triple-mode wideband bandpass filter (BPF) is proposed in this paper. Three resonant modes, namely, TM01 mode and A pair of TE11 degenerated modes, have been excited in single rectangular waveguide cavity. Meanwhile, a wide pass bandwidth have been realized and the fractional frequency bandwidth of about 29% is achieved at the central frequency of 3.1 GHz. Finally, a filter sample is fabricated and tested. The measured results are well matched with the simulated one.

A Quintuple-mode Wideband Bandpass Filter on Single Metallic Cavity With Perturbation Cylinders

A quintuple-mode wideband bandpass filter (BPF) on a single circular waveguide cavity with perturbation-oriented cylinders is proposed. These five resonant modes are the fundamental TM01 mode, a pair of TM11 degenerate modes, and a pair of TE11 degenerate modes. Three metallic cylinders are installed on the bottom of an intra-cavity to excite TM modes, and two coaxial feed probes are used to further separate the paired TE11 modes. A wide passband under the resonance of these five modes is achieved with 36% fractional bandwidth. To prove the validity, the proposed filter is fabricated using silver-plated aluminum metal cavity. The measured results are in good agreement with the simulated results.