Zhong Liang Deng

A novel tunable band-pass filter using MEMS technology

This paper presents a band-pass tunable filter (BPF) within frequency ranges of 13-20GHz and it shows good stop rejection and sharp roll off frequency. It used a novel design to turn the resonant frequency by micro-electromechanical systems (MEMS) switch and coplanar-waveguide (CPW) structures. The DC voltage is utilized to load RF-MEMS switch as source of the tunable cells power. The simulation obtained by HFSS and ADS tool shows that insertion loss is less than 1dB in pass-band and return loss is greater than 10 in the stop band.

Ka-Band Radiation Pattern Reconfigurable Microstrip Patch Antenna Employing MEMS Switches

This article describes the design of a microstrip patch antenna with radiation pattern reconfigurable characteristic, where two monolithically integrated MEMS switches are utilized. By changing the physical dimension of the antenna, its radiation pattern could be changed. Moreover, we present detailed structures of these RF MEMS switches, whose isolation and insertion loss are-23.12 dB and-0.09 dB at operating frequency, respectively. And the resonant frequency of the antenna is 35.4 GHz and the bandwidth is 6.69%. All the results are simulated.

An Indoor Location Algorithm Based on Grid Characteristic Match by TDOA-RSSI

According to indoor wireless environment and signal propagation model, an indoor location algorithm based on grid characteristics match by TDOA-RSSI combining is put forward in this paper, in which the RSSI and TDOA parameters are combined as grid characteristic parameters to calculate the weighted Euclidean distance. The location algorithm adopts KWNN algorithms for grid matching and location estimate. Simulation results show that this algorithm has better robustness and accuracy, and can effectively solve the problem of location estimates stability in general RSSI fingerprint location system.

Design and Simulation of K Band RF MEMS Tunable Combline Filter

Tunable bandpass filters are generally preferred and are used extensively in the mobile communication systems. In this paper, a design of the RF MEMS tunable combline bandpass filter is proposed. Firstly, the theory of the RF MEMS tunable combline bandpass filter is presented. Secondly, a combline bandpass filter which have a tunable frequency range from 18GHz to 27GHz is designed and simulated by using the EDA simulation software. Its bandwidth is about 1GHz in the tunable frequency range. From the simulation results, the designed filter is not only compact and effortless to fabricate but also relatively superior in some aspects.

Research on NLOS Mitigation Method for TOA Positioning

In Time of Arrival (TOA) positioning technology based on base station (BS), besides the measurement error caused by mobile station (MS), Non Line Of Sight (NLOS) propagation become the main factor of the positioning error. Aiming to solve this problem especially in indoor positioning, we introduced the differential calculus method to linearize the positioning equations, and Mirror Image Method (MMI) to turn the NLOS propagation into LOS propagation, then we collected a small amount of feature point information in the positioning region which include the received TOAs at this point, feature point coordinates and BS coordinates or the mirror image coordinates of BS. In the following 3D scenario simulation, we took use of the differential calculus as well as Least Square (LS) method to get the position of the MS. Simulation results show that by using the whole mechanism, we can achieve a high positioning precision.

Anti-Perturbation Kalman Filter Based on Perturbation Theorem and Multiple Hypothesis Testing Theory

In this paper, an improved Kalman filter algorithm was proposed by two kinds of anti-perturbation method which were derived according to the perturbation theorem of inverse matrix. Furthermore, direction-correcting has been merged into this algorithm by using multiple hypothesis testing theory which can detect the current direction of a target. Experiments which were based on indoor positioning have shown that the improved algorithm(named IKF) has great performance.

Design and Simulation of a Ka-Band Pattern Reconfigurable Microstrip Patch Antenna

This letter presents a Ka-band(26.5GHz-40GHz) microstrip patch antenna with pattern reconfigurable characteristic. The antenna is provided with five rectangular patches and four RF MEMS (microelectromechanical systems for RF circuits) switches. The central patch and other surrounding patches are connected by the switches. By changing the states of the switches, the antenna can achieve four radiation patterns and it is designed and simulated by using Ansoft HFSS. In addition, the different states are operated at the same centre frequency of 35GHz and the gain of the main radiation direction is about 7.5dB

Design of a K Band MEMS Switch with CPW Defected Ground Structure

This paper presents a K band (18GHz-26.5GHz) shunt capacitive micro-electromechanical systems (MEMS) switch. This switch used the coplanar waveguide (CPW) Defected ground structure (DGS) which is made by etching defect structure in CPW ground line. Furthermore the beam structure of the proposed switch is composed of one girder and two supporting beams. The design of the switchs structure is benefit to the apart between the DC signal and AC signal. The simulated values of the isolation of the switch on off-states is-55 dB at18.9 GHz, and the return loss at K band is greater than-0.3 dB. The pull-in voltage of the switch is 13.3 V.

An Enhanced Weak Signal Acquisition Algorithm for Indoor Positioning Receiver

This paper focuses on the research of weak signal acquisition based on time-division CDMA-OFDM (TC-OFDM) system by using long PN sequence with low power. An enhanced weak signal acquisition algorithm is proposed to improve the ability of weak signal acquisition compared with regular algorithm which uses short PN sequence with high power. Simulation shows that the ability of resistance to white noise in weak signal acquisition is enhanced by 12dB. Further, because of the good correlation of long PN sequence, the performance of resistance to strong signal interference has also improved 6dB.

A BOC Signal Synchronization Algorithm Based on TK Operator

The binary phase shift keying (BPSK) modulation method is generally utilized for the traditional navigation satellite systems; however, the new generation of GNSS, such as modernized GPS, European Galileo, Chinese Compass, etc., will apply binary offset carrier (BOC) modulation technique, which can efficiently split the spectrums of navigation signals using the same frequency so as to reduce the interferences among different systems. But the autocorrelation function of BOC modulated signals has the drawback of multimodality, so it’s very hard to synchronize to the right peak when acquiring and tracking signals, especially under low SNR circumstances, which can decrease the positioning accuracy and even lead to wrong positioning results. A BOC modulated signal synchronization algorithm based on TK (Teager-Kaiser) operator is proposed in this article, which could eliminate all the other peaks in autocorrelation function of BOC modulated signals, and create an ideal curve with only one right peak. As a result, this method could avoid the false lock of code phase and guarantee the high precision fix results.