Research On CTS Antenna

Nowadays, more and more attention is paid on multi-frequency technology in modern communication development, for the technique is applied in electronics system, such as public communication system, satellite communication, RFID and so on. Recently, various terminal equipments are required to supply different services. Usually the carrier wave for these wireless services is not is the same frequency-band, so antennas applied at several frequencies is developed by engineers.In this paper is an omnidirectional CTS (Continuous Transverse Stub) antenna, which is easy to be designed to supply multi-frequency, is studied and the device is low-cost in manufacture, with high radio efficiency. For those characteristics, it could be assembled in personal communication system and satellite equipment.Firstly, after an observation on CTS structure, it is known that the antenna can be analyzed in two aspects. For one thing, coaxial CTS antenna is a form of bipyramid antenna, so density of field and radiation pattern is able to be deduced with the equations for bipyramid. For the other, because of the cascade structure, the theory for microwave circuit is used to analyze CTS antenna. Through this way, the transmission and radio efficiency is got.Secondly, CTS element is calculated by electromagnetic simulation software. The relation between stub width and resonant frequency is studied, and other results, such as farfield, gain, radiation efficiency and phase difference between two ports, are given. To connecting elements two methods, matrix parameter method and matching method, are proposed. Designer use them to connect CTS elements.Thirdly, according to the simulation results above, two antennas at different frequencies are obtained respectively, and they are connected with matching method. In the optimization, no–symmetry CTS is used to get higher gain and a monopole is placed at the end of the antenna to improve radiation efficiency. The performance of coaxial CTS antenna becomes better than the mod before optimization.Finally, a coaxial CTS is manufactured, and some results, such as return loss and farfield pattern, is measured in experiment. Comparing the results from experiments and simulations, analysis for the antenna is given.