Q.-Y. Feng

Half-Mode Substrate Integrated Waveguide (HMSIW) Filters and its Application to Tunable Filters

—In this paper, novel bandpass filter and tunable bandpass filter are designed based on half-mode substrate integrated waveguide (HMSIW) embedded with complementary resonators. Various passband characteristics are observed, and lumped equivalent circuit analysis models are developed. The configuration of the proposed bandpass filter is an open structure, and it is easy to load the active devices and build the bias/control networks on the signal plane. The tunable bandpass filter is presented based on the proposed novel bandpass filter loaded with semiconductor varactor diodes, and it has good spurious suppression characteristics and excellent out of band rejection. The prototype with overall size of 15.9 mm × 30.2 mm × 0.5 mm was designed and fabricated so as to validate the new structure. The measured central frequency is 1.538 GHz and 1.718 GHz, and the insertion loss is 5.1 dB and 3.3 dB, at 0 V and 30 V, respectively.

Bandstop Filter based on Complementary Split Ring Resonators Defected Microstrip Structure

Novel bandstop filters based on the defected microstrip structure with complementary split-ring resonators (CSRRs)/half-CSRRs etched on the microstrip surface are presented in this paper. By changing the configurations of the CSRRs, varied stop-band and pass-band characteristics are observed, and half-CSRRs is proposed to build a novel bandstop filter. A detailed explanation for the generation and variations of the stop-band and pass-band has been given. Lumped equivalent circuit analysis model is developed as well. The proposed filters exhibit compact size due to the employment of sub-wavelength resonators, and the overall size of the prototype is 12.2 mm × 28.95 mm × 0.8 mm. The measured −20 dB bandwidth of S 21 is from 2.51 GHz to 3 GHz, and the S 21 exhibits a wide spurious free response up to 10 GHz.

Substrate integrated waveguide filters and mechanical/electrical reconfigurable half-mode substrate integrated waveguide filters

In this paper, novel evanescent mode substrate integrated waveguide (SIW) and half-mode substrate integrated waveguide (HMSIW) filters are proposed, and their applications to mechanical and electrical reconfigurable bandpass filters (BPFs) are studied. SIW and HMSIW loaded with coupled complementary split-ring resonators achieve forward electromagnetic wave transmission below the waveguide cutoff frequency due to evanescent wave amplification. The half-mode configuration of the proposed SIW BPF is an opening structure, and the proposed HMSIW BPF is suitable to load with control elements. The electric/magnetic coupling effects and frequency responses reconfigurable mechanics of the proposed HMSIW structure are studied based on lumped equivalent circuit model. By using floating capacitors with mechanical switches and PIN diodes loaded on the HMSIW resonators, two one-bit HMSIW 500 MHz mechanical and 300 MHz electrical reconfigurable BPFs are demonstrated.

A Novel Microstrip Bandstop Filter and its Application to Reconfigurable Filter

Abstract In this paper, a novel bandstop filter based on microstrip LC resonators and 1-bit frequency reconfigurable bandstop filter are presented. The configuration of the proposed LC resonators has open structure and is suitable to load with reconfigurable capacitors. Lumped elements models have been developed, and the frequency tuning capability of the bandstop filter is studied, and it is shown that the filter stopband can be reconfigured by the loading capacitance. A 1-bit reconfigurable bandstop filter is designed based on the proposed novel bandstop filter loaded with two switchable 3.5mm × 6.5mm × 0.508mm Rogers 5880 single metal plane PCB capacitors. The prototype with compact overall size of 22mm × 39mm was designed and fabricated to validate the new structure. The measured stop-band central frequency is 3.04GHz and 2.513 GHz in cutoff state and connected state, respectively. 500 MHz central frequency reconfigurable capability is obtained.

A compact tri-band monopole antenna with metamaterial loaded for WLAN/WiMAX applications

An asymmetric coplanar waveguide (ACPW)-fed tri-band monopole antenna with metamaterial loaded is investigated. The designed antenna comprises of a rectangle patch radiating element, a strip, and a complementary spilt-ring resonator (CSRR)-shaped slot. By embedding a trip connected between the rectangle patch and an ACPW ground plane, an epsilon negative transmission-line metamaterial loaded is achieved to obtain a zeroth-order mode. By embedding a CSRR-shaped slot in the patch leads to another resonant frequency at high band. A prototype designed on ArlonAR350(tm) substrate with dielectric constant 3.5 occupies an overall size of 14.5 × 25 × 0.8 mm3. The measured results show that the proposed antenna operates over the frequency ranges of 2.35–2.61 GHz, 3.38–4.01 GHz, and 4.25–6.65 GHz. It is suitable for WLAN 2.45/5.2/5.8 GHz and WiMAX 3.5/5.5 GHz applications.

High Selectivity Broadband Bandpass Filter Using Stub-Loaded Quadruple-Mode Resonator

—In this paper, a compact and high selectivity broadband microstrip bandpass filter (BPF) using stub-loaded resonator is proposed. The basic block of the proposed filter is a quadruple-mode resonator consisting of a stepped-impedance resonator and three shunt open stubs. The proposed resonator can provide two even-mode, two odd-mode frequencies and two transmission zeros. The even-mode resonant frequencies can be flexibly controlled by the centre stub, while the odd-mode frequencies are fixed. The two other symmetrical stubs can both affect even- and odd- mode frequencies. The proposed filter exhibits high selectivity profiting from the two transmission zeros (TZs) near the passband created by two types of stubs. The measured –3 dB bandwidth is 1.0 GHz at the centre frequency of 2.5 GHz, and the S 21 exhibits a wide spurious free response up to 6 GHz. Measured results show good agreements with EM simulation results.

A compact composite right-/left-handed transmission line antenna with extended bandwidth

An asymmetric coplanar waveguide (ACPW)-fed antenna with extended bandwidth is investigated. The designed antenna comprises two unit cells of composite right-/left-handed transmission line (CRLH TL). The bandwidth enhancement of the designed antenna can be achieved when the zeroth-order and first-positive-order modes merge. A prototype designed on F4BM350 substrate with dielectric constant 3.5 occupies an overall size of 14 mm × 25 mm × 0.8 mm, which is approximately 0.118 λ0 × 0.211 λ0 × 0.007 λ0. The measured result shows that the operating bandwidth with 10 dB return loss is about 330 MHz (2.44–2.77 GHz), and the peak gain and radiation efficiency simulated are 1.37 dBi and 88% at 2.53 GHz, which are suitable for WiMAX (2.5–2.69 GHz) application.

RF power amplifiers behavioral modeling based on extended neural network with additional dynamic fuzzy weights

This paper presents an extended neural network (NN)-based behavioral model of RF power amplifiers (PAs) with memory effects. PA behavioral models are traditionally constructed based on the relationship between the input and output of PA, without regard to the physical mechanisms of distortions in PA however. To more accurately predict the dynamic nonlinear behavior of PA, the novel proposed NN-based behavioral model takes into account the characteristics of the amplitude modulation to amplitude modulation and amplitude modulation to phase modulation distortions that are incorporated into the behavioral model by means of additional dynamic fuzzy weights. In addition, the NN-based behavioral model employs orthonormal Hermite polynomial functions rather than commonly used sigmoid function, as nonlinear activation functions resulting in significant improvement in accuracy and convergence. Experimental results on a class-AB PA driven with the wideband Mobile Multimedia Broadcasting signals show a superior performance of the proposed extended NN-based model over the traditional NN-based ones.

A two-pole tunable filter with constant fractional-bandwidth characteristics

In this paper, a tunable filter with constant fractional bandwidth is designed and fabricated on εr = 2.2, h = 0.508 mm duroid substrates. A new mixed electrical and magnetic coupling scheme is introduced by this structure to achieve an overall constant coupling coefficient during the tuning range, which can meet the requirement of constant fractional bandwidth. A detailed analysis on the external quality (Qext) and coupling coefficient is presented. Two-chip capacitors (CM = 1 pF), using radio frequency (RF) and microwave capacitors, were used to enhance Qext. The Qext (22 ± 3) shows a relatively small variation over the entire tuning range. The tunable constant fractional-bandwidth filter shows a tuning range of 1.28–1.86 GHz, a 3-dB bandwidth of 5.3 ± 0.6% and an insertion loss of 5.11–2.69 dB. The measured and simulation results are in a good agreement.

Compact tri-band bandpass filter with good selectivity

A novel tri-band bandpass filter (BPF) based on two multi-mode resonators is presented. The even–odd-mode analysis method is adopted to calculate the resonant modes of the resonators. The formation of each passband is analysed in detail. Furthermore, introduction of seven transmission zeros adjacent to the passbands in a narrow frequency range improves the selectivity of the system, resulting in sharp skirts. Due to the small multi-mode resonator and tight coupling structure, the overall size of the proposed filter is really compact (0.19 λ0 × 0.19 λ0), where λ0 is the wavelength of the centre frequency of the first passband in the substrate. Finally, a prototype to demonstrate the performance of the proposed tri-band filter is designed and fabricated. The locations of the passbands are chosen to be 2.29, 2.81 and 3.42. The measurement shows good agreement with the simulation. The proposed tri-band BPF can be applied to F-band multi-mode RF front end systems.