Zong Hua

A planar printed quasi-Yagi antenna with a parabolic reflector for WLAN

The simplicity and intuitive design of traditional planar printed quasi-Yagi antennas has led to its widespread popularity for its good directivity. In this paper, a planar printed Quasi-Yagi antenna with 3 directors and 1 concave parabolic reflector, operating in S-band, is proposed. The impedance and radiation characteristic are simulated with CST-Microwave Studio, and the antenna is fabricated and measured. The measured results indicate that the antenna which operates at 2.25-2.63GHz can achieve an average gain of 9.45 dBi within the operating frequency range, especially a highest gain of 10.3dBi at 2.45GHz, which can be widely used in WLAN.

A low-profile vertical polarized omnidirectional radiated and broadband printed antenna

In this paper, a low-profile vertical polarized omnidirectional radiated and broadband printed antenna was proposed. This antenna forms a transmission lines structure similar with parallel lines by using metal vias and coaxial feed inner conductor. Then the distributed inductances and capacitances of transmission lines are used to yield resonance with loaded capacitance of antenna itself. Therefore, this structure can realize wide range of working frequency and has omnidirectional radiation characteristics. The simulated results by CST Microwave Studio software indicate that the reflection coefficient of the antenna is less than -10dB and relative bandwidth is up to 49% from 2.40GHz to 3.95GHz. Also, the corresponding omnidirectional gain is up to the range from 1.3 dBi to 4.2 dBi. The dimension of this vertical polarized antenna is 10mm on the polarization direction, which is only 8% of the lowest working frequency corresponding to the wavelength. Hence, the antenna achieves well low-profile effects. The working frequency band covers WLAN/WiMAX bandwidths.

Array antenna pattern synthesis method based on intelligent algorithm

The paper introduced the basic theories of intelligent algorithms, equally spaced linear antenna array and antenna pattern synthesis principle, also introduced the related omni-directional antenna. The procedure, parameter settings, characteristics of genetic algorithm and the neural network algorithms were demonstrated that used in the pattern synthesis, then the simulation programs were given. In the experimental stage, three groups of three different DOA of interference signal were applied to the antenna array model, respectively. The genetic algorithm and neural network algorithm were applied to the array pattern that simulated, then the simulation results were statisticed to compare their accuracy and robustness. At the same time, the linear antenna array model was established by the FEKO simulation software, whose antenna element is omni-directional COCO antenna whose center frequency is 1.8GHz. The weight coefficient produced by genetic algorithm and neural network algorithm were applied to the excitation voltage of every array elements, whose amplitude and phase is controlled by the weight coefficient. Then the results were analyzed which came from the two intelligent algorithms with different interference signals.