Phaisan Ngamjanyaporn

Signal-to-interference ratio improvement by using a phased array antenna of switched-beam elements

A phased array antenna of switched-beam elements is proposed to improve the signal-to-interference ratio (SIR). By using 1-bit phase shifters, the main beam of the array is switched to desired signal direction, and with the switched-beam patch antenna elements the null patterns are changeable. The results of radiation patterns show that the interference suppression can be improved. Moreover, the SIR measurement is also set up in multipath environment to ensure the array performance. It is found that the SIR is significantly affected by the multipath environment; however, the SIR improvement of more than 10 dB can be obtained by changing the null patterns.

A flat four-beam compact phased array antenna

This paper presents a flat four-beam compact phased array antenna. The low-cost and compact phased array antenna is designed using a circular array of four circular microstrip antennas made of low-cost material and four 1-bit phase shifters. The main beam of the antenna can be switched in four directions with the gain of about 4 dBi in each main-beam direction. More than 90/spl deg/ half-power beamwidth and over 10 dB F/B ratio are obtained. In addition, the diversity performance is considered and the diversity performance of this antenna can be provided with the envelope correlation about 0.6.

Analysis of circular array of monopole on the ground plane radiating linearly polarized conical beam for wireless LAN applications

An analysis of a conical beam antenna using circular array of monopole on the ground plane is presented. This antenna was proposed for application to the HIPERLAN system. The structure of this antenna type is simple and easy to fabricate. The radiation pattern of the antenna is calculated by combining the total fields radiated from each monopole on the ground plane. The effect of the finite size ground plane is taken into account and found that it affects the back lobe level. Moreover, it is apparent that a nondirectional azimuthal pattern is realized when the circumferential spacing is sufficiently small. The radiation patterns for various parameters such as the array radius and the number of elements are demonstrated. Antenna measurements are set up to verify the proposed principle. The theoretical and experimental results are in good agreement.

Design of a spherical array self-mixing oscillator antenna

Principle of a spherical array self-mixing oscillator antenna is discussed in this paper. Applying the injection locking technique to the spherical array, in which elements are made of simple waveguide radiators, beam steering with constant pattern in different directions can be achieved without using the sophisticated phase shifters. This antenna is designed and tested at a frequency of 10 GHz.