On Study Of Microstrip Antennas For Personal Communication

The operation principle and design method of microstrip antenna used for personal communications are described, based on transmission line theory and equivalent theorem, in this paper. Using the formula of far field radiation from electric currents and magnetic currents that are on any shapes of curve surface, we calculated the radiation patterns of microstrip antenna element and array. For the impedance changes with the frequency very sensitively, usually, the microstrip antennas bandwidth is narrov. We studied the method of extending the bandwidth of microstrip antennas. The microstrip antenna element and microstrip antenna array are made by author have a wide bandwidth for 17.8% relative value to the center frequency. Within the operating bandwidth, which from 1860MHz to 1960 MHz, the maximum voltage standing wave ratio (VSWR) is 1.29. This fit the specifications in the proposal, which is below 1.5, very well. In this paper, we present the designing of single microstrip radiator and four-element microstrip antenna array. The feeding methods could be found in many papers and books. We present a kind of special feeding method. This method, using the special relation between the radiant resistance and characteristic impedance, realize the wide-banded matching. And the gradual change transmission line was used in this matching. When calculating the parameter and direction patterns of antennas, plotting them, the MATLAB program is used. When we design the antenna array, a power distributor would be used. This paper presents an adaptive power distribution network. In the bandwidth of 20% relative to the center frequency, the input VSWR value of the network is 1.04. So, this kind of adaptive network gives a favorite base for the designing of antenna array. The testing and analysis of testing results is the important part, too. This part not only present the fitness and unfitness between the testing result and designing parameter, but also gives the advise for improve design. At the final part, we give some proposal about designing new types of the base station antennas. It could resolve the problem of non-circle degree, which occurs in the Omni- directional antennas.