Search

A 3D flower-shape ultra-wideband antenna array, with performance of dual circular-polarized, for the monopulse application of tracking radar has been designed and tested. The array, constructed by eight vivaldi-shape antennas, has a stable wide beam of sum-and-difference patterns on working band and gain of 10.5 dB. The sum and difference patterns can be obtained by out-phase excitations of the eight coaxial ports. The measurement results demonstrate that the working bandwidth of the proposed antenna array is up to 170%. The simulation result shows that, the 3-dB beamwidth of the sum pattern both for the E plane and H plane is more than 30° over the working bandwidth, and the null depths of the difference pattern are below -30 dB in both planes.

A S-band planar six-way power divider which uses three compact, symmetric Wilkinson [1] dividers connected to a Luzzato [2] divider is proposed in this paper. Microstrips are used in the design of the six-way power divider over a frequency range of 3.1–3.4 GHz. The substrate of the six-way power divider has been manufactured in a hexagon structure. Good agreement has been obtained between the measured and simulated results.

The traditional indoor location algorithm based on distance-loss model mostly turn received signal strength indicator RSSI into distance, and then through the location-distance algorithm to achieve positioning. These algorithms need fit the wireless signal propagation model parameters A and N through experience or large amounts of data, so they are dependent on experience and are not strong universal algorithms for location of the different environment, also low accuracy. After lots of research and analysis of radio signal propagation model and the traditional indoor location algorithm, a new indoor location algorithm uses BP neural network to fit the distance-loss model is proposed. From a number of distances between reference nodes and blind node, Taylor series expansion algorithm is used to determine the coordinates of the blind node. Finally, the experiment result shows that the new algorithm improves the positioning accuracy and universality, compared with the traditional positioning algorithms.

On the basis of Wu-King current distribution, the author extends it to the double exponential current distribution, modifies the inaccurate part of the Wu-King resistive loading profile and deduces a high efficiency non-reflecting loading profile. The electrical properties of the high efficiency non-reflecting loading antenna have been studied theoretically; the concept of lengthening coefficient is created and the optimum parameter design curve of the antenna is provided. Theoretical calculation shows that the maximum bandwidth and efficiency of antenna can be achieved with this kind of loading profile simultaneously. The impedance bandwidth of antenna is as high as 40:1, which is much greater than the 3:1 bandwidth of Wu-King profile when the voltage standing wave ratio is below 3. The efficiency of antenna is about twice of the Wu-King loading antenna.

One of the most critical hardware components for the performance of the UWB system is the antenna and the resistive loading antenna is one of common antennas used in the system. The author extends Wu-King linear current distribution to the double exponential current distribution and modifies the inaccurate part of the Wu-King loading profile and deduces an improved loading profile with high efficiency. The broadband performance of the improved resistive loading antenna has been studied; the concept of lengthening coefficient is created and the optimum parameter design curve of the antenna is provided. Numerical analysis shows that the improved resistive loading antenna exhibits better bandwidth and efficiency than Wu-King antenna. It can reduce the late-time ringing, enhance the pulse radiation characteristics of UWB antenna. The improved loading profile can be widely applied to other resistive loading antenna for UWB applications.

An effective method is presented to depress mutual coupling between patch antennas by means of a multi-layer dielectric boards structure. For simplicity, a patch array antenna with only two probe-fed rectangular patches is dealt with. By adding multi-layer dielectric boards over this original antenna, we obtain the modified model. Both models are simulated to obtain the scattering parameters and mutual impedance. Simulation results indicate that mutual coupling between two patches is greatly depressed when adding multi-layer dielectric boards over the original model.

Genetic algorithm (GA) is used to design a type of sector array antenna for smart antenna system front end. The sector array antenna is mainly applied to the base station of TD-SCDMA. Firstly, to meet the demand of smart antenna system sector coverage mode (namely broadcast mode), the arrays configuration and element weight arc obtained by the global-search GA. Secondly, element weight is optimized to simulate the tracking mode (namely working mode) by GA. The sector antenna array of practical smart antenna system is analyzed, which is meaningful for the smart antenna technology.