Kaida Xu

NOVEL DESIGN OF A COMPACT TRIPLE-BAND BANDPASS FILTER USING SHORT STUB-LOADED SIRS AND EMBEDDED SIRS STRUCTURE

A novel compact planar triple-band bandpass fllter using two sets of short stub-loaded stepped impedance resonators (SSLSIRs) and a pair of embedded stepped impedance resonators (ESIRs) has been proposed. The SSLSIRs can adjust the bandwidths of the corresponding passbands over a wide range, and the ESIRs employing non 0 - -feed coupled structure with mixed electric and magnetic coupling can obtain an extra transmission zero. The embedded resonators structure can further miniaturize the dimensions of the whole triple-band fllter. The operating frequencies of the SSLSIRs and ESIRs are designed for the applications of the WLAN (2.45/5.2GHz) and WiMAX (3.5GHz) systems, respectively. The simulated and measured results are both presented and show good agreement.

A broad W-band detector utilizing zero-bias direct detection circuitry

In this paper, a broad W-band detector utilizing zero-bias direct detection planar circuitry with high voltage sensitivity and enhanced tangential signal sensitivity (TSS) is proposed, which is intended to apply for W-band radiometer. The commercially available GaAs detector diode Agilent® HSCH-9161 is adopted to build an unamplified zero-bias direct detector, along with probe transition, broad band microstrip impedance matching network and low pass filter. Voltage sensitivity up to 1000 mV/mW from 75 GHz to 104.5 GHz (almost full W-band) is achieved. A self-manufactured video amplifier is used to set the video bandwidth (VBW) as approximately 70 Hz and the obtained TSS is better than −51 dBm in the full W-band. The whole circuit is based on microstrip circuits and is hence easy and cheap to fabricate, which satisfies the low cost requirements of assembling large passive millimeter wave imaging array.

Compact triple-mode bandpass filter using short- and open-stub loaded spiral resonator

A novel high-selectivity triple-mode microstrip bandpass filter (BPF) using short- and open-stub loaded spiral resonator is presented. Because of the spiral structure, the size of designed BPF is reduced greatly. Then the odd- and even-mode method is used to analyze resonant frequencies of the resonator. Based on the analysis, a prototype of the proposed BPF with good selectivity is designed whose center frequency is at 4.3 GHz. Finally, the measured results are shown, which are in good agreement with simulations.

SPICE model of memristor and its application

In this paper, a circuit model of the memristor using SPICE is presented, which expands the hitherto methods to solve the memristors modeling equations presented by HP lab. This kind of the memristor model can not only be encoded in SPICE and satisfy the properties of the general memristive systems, but also use few components and simulate fast. In order to further explore the nonlinear and switching characteristics of the memristor model, a directly modulated patch antenna with one memristor is designed by using finite-difference time-domain (FDTD) simulator integrated with the nonlinear SPICE circuit solver.

Nano-scale memristor SPICE implementation using ideal operational amplifier model

The conception of memristor is becoming increasingly prevalent due to its remarkable electronic properties. In this paper, a circuit model of the memristor using simple SPICE code is presented. An ideal closed-loop operational amplifier (OP-AMP) is applied to realize the feedback-controlled integrator, which expands the hitherto methods to solve the memristor’s modeling equations presented by HP Lab. The behaviors of the proposed memristor model in SPICE are investigated. The desired excitation source and initial condition of the doped state can both be easily tuned in the memristor model. Different pinched hysteresis loop i-v curves are presented through different stimulus like sinusoidal and square-wave voltage source.

A Coplanar Waveguide Fed UWB Antenna using Embedded E-shaped Structure with WLAN Band-rejection

Abstract A compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) monopole antenna using embedded E-shaped structure with wireless local area network (WLAN) band-rejection is presented. The introduction of this E-shaped structure working as the radiator can enhance the impedance bandwidth of the UWB antenna without increasing the overall size. For preventing the interference from WLAN system, a pair of L-shaped stubs are connected to the ground of UWB antenna to create the rejected band. The center frequency of this rejected band is about 5.5u2006GHz with the rejection range of 5.2~5.8u2006GHz. Good agreement can be observed between the simulated and measured results.

Miniaturized quad-band bandstop filter with controllable frequencies using multiple-mode resonator

The operating mechanism of the quad-band band stop filter (QB-BSF) with multiple-mode resonator (MMR) is introduced in this paper. Based on the design procedure, the operating stopband frequency locations of the proposed QB-BSF can be conveniently controlled. Also, the BSF features compact size and sharp roll-off skirts for transition bands. As an example, a QB-BSF centered at 1.23/1.8/2.4/3.5GHz with respective rejection levels of 22.5/47/52.1/23.7 dB has been designed.

A dual-polarized SIW cavity backed slot antenna

A novel design of dual-polarized substrate integrated waveguide (SIW) cavity backed slot antenna using three-layer substrates is presented in this paper. Two pairs of radiating slots placed orthogonally with rotated 45° are etched on the first copper layer, which will generate two orthogonally linear polarized radiation pattern at 19 GHz to implement polarization diversity technique. The TM330 mode is selected as the working mode of the resonant SIW cavity. The simulated results show that the isolation between two feeding ports is better than 40 dB and the peak gain can reach 9 dBi in broadside direction.

Planar microstrip tri-mode bandpass filter using center-stub-loaded spiral resonator

A new tri-mode banpass filter (BPF) using a half-wavelength spiral resonator center-loaded with two T-shaped open stubs has been presented. Analyzed by the odd- and even-mode method, an odd mode and two even modes of the proposed tri-mode resonator could be flexibly controlled by tuning the electrical length of the spiral resonators and T-shaped stubs. For demonstration purpose, a tri-mode filter example with passband centered at 1.8 GHz has been implemented.

Planar interdigital-coupled UWB bandpass filter with a notched band

This paper presents a planar compact microstrip interdigital-coupled notch-band ultra-wideband (UWB) bandpass filter (BPF). The proposed five high-impedance interdigital lines are employed to not only realize strong coupling as feed lines, but also create a controllable notched band in the UWB passband. A prototype of the proposed notch-band UWB BPF has been designed and fabricated. The measured results illustrate that the 3 dB fractional bandwidth (FBW) of the filter is 125%, and the insertion loss of the notched band within the UWB passband is 12 dB at 5.8 GHz.