Dual Polarized Phased Array Antenna Simulation Using Optimized FDTD Method with PBC

It has been a goal to develop a fast, accurate and open-source pattern prediction tool for Multi-functional Phased Array Radar (MPAR). In this paper, a finite-difference time-domain (FDTD) simulation of dual polarization phased array antenna based on both regular lattice and the mirrored element configuration is presented. The numerical model is based on a sine-cosine method for periodic boundary condition (PBC) to simulate finite phased array antenna. Even though sine-cosine method can simulate phased array antenna with beam steering, it has a limitation of narrowband. It has been presented in literature, that Array Scanning Method (ASM) is one way to overcome this drawback. Array scanning method can be used to deal with non-periodic excitations and can be used in wide-band simulation of dual polarized array antenna. Similar to basic FDTD, ASM may be extended to different types of manifolds including planar and cylindrical. If a single dual polarized patch antenna simulation for N time steps is consuming T CPU time with FDTD algorithm, m×n dual polarization phased array antenna based on the regular or mirrored elements configuration consumes mnT CPU time with the same FDTD algorithm. The same regular elements configuration antenna is simulated with the FDTD algorithm in this work, which takes almost the same CPU time as single element. The mirrored element configuration with the same radiating elements may take 2T CPU time, since two elements will be required to simulate for an array with the cross polarization suppression in both H and V channels. In both simulations, memory allocation sizes for updating coefficient arrays are the same as one-element (non-mirrored case) or two-element (mirrored case) simulations. Compared to some other tools used in commercially available applications, this simulation offers a great improvement in reduction of CPU time and memory consumption. The implementation was done using ANSI C programming and used GNU GCC compiler to build and optimized the code. The program can be ported to any environment where the ANSI C compliant compiler is available. It is more than 100 times faster than the similar MATLAB code and is being extended to Graphic Processor Unit (GPU) implementations. As a validation example, micro-strip patch antennas with 3.3 GHz center frequency and 1.3741% bandwidth for VSWR < 2 are used to create an 8x8 planar array antenna with both regular and mirror configurations. Measurements of a dual-polarized 64-element (8×8) array are used to validate the FDTD simulation results, and simulations using commercially available application (ANSYS HFSS) will be used to compare the computational performance, accuracy and precision. 64-element, dual polarized phased array needs 128 TR modules for beam steering radiation pattern measurements. In order to avoid the need of TR modules, active element patterns of each element are used to generate the measured array pattern. Measurements of active element patterns are taken using a near-field range in OU and the generation of the array patterns with proper calibrations are performed using MATLAB program.