Zhiya Zhang

A New Compact Filter-Antenna for Modern Wireless Communication Systems

Design, fabrication, and measurement of a new compact filter-antenna for modern wireless communication systems are presented in this letter. Two microstrip square open-loop resonators, a coupled line, and a Γ-shaped antenna are used and integrated to be a filter-antenna. The Γ-shaped antenna is excited by a coupled line that is treated as the admittance inverter in filter design. The Γ-shaped antenna performs not only a radiator, but also the last resonator of the bandpass filter. Therefore, near-zero transition loss is achieved between the filter and the antenna. The design procedure follows the circuit approach-synthesis of bandpass filters. Measured results show that the filter-antenna achieves an impedance bandwidth of 16.3% (over 2.26-2.66 GHz) at a reflection coefficient |S11 | <; - 10 dB and has a gain of 2.41 dBi.

Wideband Circularly Polarized Antenna With Gain Improvement

A wideband circularly polarized antenna with coaxial balun feed, using a broadband 90° hybrid feed network, is proposed. By introducing a narrow patch connecting the pair of bowtie dipoles as an entity that increases the effective radiation area, the proposed antenna delivers a higher gain than that of the conventional dual-fed-type circularly polarized antenna. It can achieve a measured impedance bandwidth for VSWR ≤ 1.5 of 57% and a 3-dB axial-ratio bandwidth of 51.8%. Moreover, the antenna has stable peak circularly polarized gain better than 9.0 dBi ranging from 1.1 to 1.6 GHz. For the entire half-power beamwidth, the axial ratio can be kept below 3 dB.

A Wideband Dual-Sleeve Monopole Antenna for Indoor Base Station Application

The design and enhanced bandwidth performance of a dual-sleeve monopole antenna for indoor base station application is presented. By a top-loading circular patch shorted to the ground plane through four shorting probes, the size reduction is achieved. The dual-sleeve structure is successfully employed to improve the impedance bandwidths through achieving another two resonant modes. A measured impedance bandwidth for VSWR ≤ 2 of about 137% ranging from 730 to 3880 MHz is achieved. It is very suitable for GSM900, DCS1800, PCS1900, UMTS, IMT2000, WiBro, WiMAX2350/3500, and wireless LAN (IEEE 802.11b).

Wideband Dual-Polarized Crossed-Dipole Antenna with Parasitical Crossed-Strip for Base Station Applications

A wideband dual-polarized crossed-dipole antenna with parasitical crossed-strip for base- station applications is presented. By using a pair of orthogonal crossed-dipoles, two linear polarizations (§45 - ) are obtained. A parasitical crossed-strip is introduced to improve the impendence bandwidth and enhance the isolation (S12) between the two orthogonal polarizations of the upper band. The antenna shows a wideband impedance characteristic about 34.9% for S11 • i10dB (+45 - polarization) and S22 • i10dB (i45 - polarization). High isolation (S12 • i32dB) between the two polarizations in the required band are obtained. The stable peak gain, unidirectional radiation patterns and low cross- polarization over the whole operating band are also achieved. Due to its good performance, simple fabrication technique and low cost, the antenna is very suitable for potential base station applications in mobile communication such as DCS, PCS and UMTS.

Dual-Band CP Antenna With a Dual-Ring Cavity for Enhanced Beamwidth

A dual-band circularly polarized (CP) antenna with enhanced beamwidth is proposed in this letter. Stacked cone-patches including a small patch for upper band (1561 ± 2 MHz) and a large one for lower band (1268 ± 10 MHz) are used to achieve the dual-band operation behavior. To widen beamwidth for the two operation bands, a dual-ring cavity is employed for the proposed antenna. The dual-ring cavity is formed by a large ring and a small ring, which are used to improving the beam performance for lower and upper band, respectively. Over the dual-band of interests, the impedance bandwidth (VSWR ≤ 1.5) and the axial ratio below 3 dB are both satisfied. Wide 3 dB beamwidths of about 135 ° and 112 ° at center frequencies (1268, 1561 MHz) of the two bands are obtained, respectively. The high gains at the low elevation (θ = 80°), only about -0.03 dB and -0.57 dB at the two frequency points, are also achieved. With these good performances, the antenna is very suitable for navigation systems applications.

Buried Object Sensing Considering Curved Pipeline

This letter presents design and implementation of a system solution, where light weight wireless devices are used to identify a moving object within underground pipeline for maintenance and inspection. The devices such as transceiver operating at S-band are deployed for underground settings. Finer-grained channel information in conjunction with leaky-wave cable (LWC) detects any moving entity. The processing of the measured data over time is analyzed and used for reporting the disturbances. Deploying an LWC as the receiver has benefits in terms of a wider coverage area, covering blind and semiblind zones. The system fully exploits the variances of both amplitude and phase information of channel information as the performance indicators for motion detection. The experimental results demonstrate greater level of accuracy.

A Novel Single Feed Omnidirectional Circularly Polarized Antenna with Wide AR Bandwidth

A novel omnidirectional circularly polarized (CP) antenna with single feed is proposed for 2.4GHz WLAN applications. Based on the zeroth-order resonance (ZOR) mode of epsilon negative (ENG) transmission line (TL), the antenna excites uniform vertically polarized E-fleld just as the monopole does. A modifled Alford loop with electromagnetic coupling fed by L-shaped strip consists of four curved branches, which is placed on the top of the antenna and generates an equivalent horizontally polarized magnetic dipole mode. Once the two orthogonally polarized components are equal in amplitude but difierent in phase by 90 - , omnidirectional CP wave can be obtained. The measured results show that the impedance bandwidth (S11 < i10dB) is 6% (2.38{2.53GHz), and the 3-dB axial ratio bandwidth in the azimuth plane is very wide which achieves 54% (1.60{2.80GHz). Additionally, the 3-dB axial ratio beamwidth is over 50 - for radiation pattern in elevation plane. Moreover, the antenna achieves excellent omnidirectional right-hand CP performance with a variation of 0.5dB in the azimuth plane and an average gain over 1.5dB across the operating band, which are well applied to the wireless system.

Monitoring of atopic dermatitis using leaky coaxial cable

In our daily life, inadvertent scratching may increase the severity of skin diseases (such as atopic dermatitis etc.). However, people rarely pay attention to this matter, so the known measurement behaviour of the movement is also very little. Nevertheless, the behaviour and frequency of scratching represent the degree of itching, and the analysis of scratching frequency is helpful to the doctors clinical dosage. In this Letter, a novel system is proposed to monitor the scratching motion of a sleeping human body at night. The core device of the system is just a leaky coaxial cable (LCX) and a router. Commonly, LCX is used in the blind field or semi-blindfield in wireless communication. The new idea is that the leaky cable is placed on the bed, and then the state information of physical layer of wireless communication channels is acquired to identify the scratching motion and other small body movements in the human sleep process. The results show that it can be used to detect the movement and its duration. Channel state information (CSI) packet is collected by card installed in the computer based on the 802.11n protocol. The characterisation of the scratch motion in the collected CSI is unique, so it can be distinguished from the wireless channel amplitude variation trend.

Sparsity-Inspired Nonparametric Probability Characterization for Radio Propagation in Body Area Networks

Parametric probability models are common references for channel characterization. However, the limited number of samples and uncertainty of the propagation scenario affect the characterization accuracy of parametric models for body area networks. In this paper, we propose a sparse nonparametric probability model for body area wireless channel characterization. The path loss and root-mean-square delay, which are significant wireless channel parameters, can be learned from this nonparametric model. A comparison with available parametric models shows that the proposed model is very feasible for the body area propagation environment and can be seen as a significant supplement to parametric approaches.

Dual-Polarized Crossed Bowtie Dipole Array for Wireless Communication Applications

A dual-polarized array with downtilted radiation patterns is proposed for wireless communication applications. The proposed dual-polarized antenna element achieves an enhanced impedance bandwidth and compact dimensions by introducing a parasitic circular patch and vertical metal cylinders, which is a good candidate for radiating elements in base station antennas. By optimizing the amplitude and phase distribution along the feed, a radiation pattern with a downtilted angle is obtained. The dual-polarized array antenna achieves an impedance bandwidth for VSWR 1.5, covering the frequency bands for 3G/LTE systems. Moreover, the proposed array achieves high port isolation, the stable antenna gain over the entire operating band. Therefore, the proposed array antenna is very suitable for potential wireless communication applications. A prototype has been manufactured and measured. The measurements, that match the design objectives, are also presented.