Simulation Design Of Planar Antenna Tuning

With the recent advances in wireless communications, there is an increase need for tunable and reconfigurable antennas to cover several frequency bands with the same structure. This eliminated the need to have many antennas, thus reducing the required area for the antennas and effects of co-site interference. In recent years, the interest in the use of ferroelectric materials in the manufacture of microwave components has grown tremendously, such as varactors, voltage tunable filters, phase shifters and voltage controlled oscillators. Thin films of ferroelectric materials can be developed to present very few losses and add no significant weight to the antenna structure. The permittivity of these materials changes with an applied DC voltage; and this change can be used to control the resonant frequency of an antenna. But nowadays the research works about the tunable antenna are still underway, and there is still no report about practical product of it. So it is necessary to do deeper research works about it.This thesis presents the theoretical analysis about the design of the tunable antennas with multilayered structure theory and microstrip antenna's analytical methods. And it improves three typical kinds of antennas, and uses the voltage controlled ferroelectric materials. We analyze the tuning features of the antenna by simulation under the condition of different permittivity of the ferroelectric materials, and discuss the feasibility of improvement from microstrip antenna to tunable antenna. At last we make a conclusion about design methods of tunable antenna that could be a valuable reference to practical work.