APAS

Is a sophisticated phased array simulator software package for the design and analysis of planar phased array antennas. It can accurately simulate the far-field characteristics of a large variety of planar phased array configurations in both the frequency and time domain.
The program is for its computational part coded in MATLAB^© while the graphical user interface (GUI) is completely programmed in Java Version 1.6. The program runs on any platform on which MATLAB Release R2015b or higher is installed. 

APAS offers accurate, high-speed computation of the far-field patterns of planar phased antennas, advanced far-field analysis capabilities and comprehensive 2D and 3D visualization of the simulated results. Execution time is minimized by coding the program as matrix operations and using 2-D FFT (Fast Fourier Transform) techniques for calculating the far-field patterns.  

Key Features

Aperture shape and element grid. The program can handle planar phased array antennas with the array elements sited in rectangular or triangular lattice configurations. For the array aperture, the user can specify a circular, elliptical, rectangular or polygon shape. The radiating elements may be grouped in subarrays and can have isotropic, cos(θ) or cos^N(θ) type radiating characteristics. By removing user selected elements, any aperture shape can be realized and subsequently evaluated.

Main beam scanning. Scanning of the main can be modeled by either phase shifters featuring constant phase shift or by time delay circuits inside the transmit/receive (T/R) modules. Moreover, it is possible  to use switchable time delay units (TDU) connected to a group of T/R modules. 

Tapers. In order to get low sidelobe patterns, the program offers the possibility to synthesize optimum sum and difference tapers for any aperture shape, any number of elements and rectangular or triangular element lattice. The implemented low sidelobe synthesis methods can deal with almost any user requirement even the most challenging ones. Optimum synthesis tapers are usually obtained within less than a minute total computation time.

Eight different analytical amplitude tapers for sum patterns and four analytical amplitude tapers for difference patterns are available. For the sum tapers, the choice can be made between Uniform, Triangular, Cosine on a Pedestal, Gaussian, Blackman, Kaiser, Bessel and Taylor. For the difference patterns, models are included for the tapers: odd Linear, odd Triangular, odd Taylor and Bayliss. 

Amplitude control. Binary amplitude control devices such as a controllable attenuator or a variable gain amplifier (VGA) and are part of the T/R modules, can be included in the simulations.

Computation time initial monopulse antenna design. An initial monopulse antenna design can be realized and evaluated within less than a few hours. This computation time includes the synthesis of the sum and two difference patterns on receive. Responsible for the short design and evaluation time is extremely high computation speed of 2D far-field pattern which is the order of less than 0.06 seconds for an array antenna equipped with 1000 x 1000 elements.  See Table 2-D FF Computation Times.