Wide-band evaluation of communications antennas using [Z] matrix interpolation with the method of moments

An important task associated with the evaluation and comparison of broadband antennas for communications applications involves performing simulations to predict the antenna performance over a wide range of frequencies. The method of moments (MoM) is one popular simulation methodology. Since the MoM impedance matrix must be computed at each frequency, the computation over a wide frequency range can take a long time. In the paper, a method proposed by Newman [1988] is revisited and applied to complex antenna structures being considered for modern personal communications applications. With this method, the impedance [Z] matrices for several relatively widely spaced frequencies are directly computed and stored. The elements of the impedance matrix at an intermediate frequency are computed by interpolating the elements of the stored [Z] matrices. This method is particularly well-suited for the analysis of antennas for personal wireless applications. Such antennas are either small and low-profile or consist of thin wires. The paper presents the results of the [Z] matrix interpolation method applied to both type of antennas; a planar inverted F antenna (PIFA) and a helix.