Antenna Impedance Analysis And Measurement

Today, as wireless communications and electronic technology development, the frequency of use increases. In circuit design, the extent of the matching circuit is increasingly demanding, especially antenna impedance matching circuit is more and more important when design circuit. Therefore, it is necessary to know more precise antenna input impedance, and explore the antenna impedance matching. Not all the antennas will be accurately calculated, and calculation antenna model is often ideal model, therefore, a quick antenna input impedance measurement program is a necessary foundation to circuit design.The purpose of this thesis is to design an antenna input impedance measurement programs aiming at the Agilent 4396B network analyzer, and certificate that the program is feasible. To compare measurements, Papers analyze and calculate the line antenna (Dipole Antenna and monopole antenna) input impedance, and against the two antennas, respectively, take the analytical method, Improved equivalent transmission electro circuit method and the finite difference time domain method. The results of calculation by a variety of methods and measurement results were compared to verify the feasibility of measuring programs. In this paper, I measured the laboratory standard antennas and two homemade antennas.This thesis carefully analyzes the broadband antenna matching network design methods, and discuss the two calculation methods of matching network elements -direct optimization and VSWR method. This paper presents two methods of matching algorithm, and optimizes matching networks components values basing on the matlab development platform. This paper innovational develope the least square algorithm of optimization objective function. This paper makes a loop antenna and measure the antenna input impedance and VSWR. and calculate the antenna VSWR ,which further tests measurement program is feasible. Based on this optimal design matching network components values, connect circuits, and measure the antenna VSWR which matching network is connected. Comparing both results, matching method improved VSWR values, and the matching degree.