Taper Synthesis 

 APAS features 5 methods for synthesizing low side lobe tapers.  These methods are labeled by the capital letters A, B, C, D and E. All five methods can be applied to planar array antennas of any size operating with a rectangular or triangular element grid and all support the synthesis of sum and difference tapers.  Each method, an iterative one,  features a very high computational speed and does not suffer from trapping and therefore does not stuck in a local optimum solution during the iterative process.

All realized tapers offer superior characteristics and are scan and frequency proof with respect to peak sidelobe level if use is made of isotropic array elements.          

Synthesis Method A

Method A is the most universal one and supports ring sector nulling and/or rectangular sector nulling. The choice can be made between amplitude-only, phase-only and complex weighting for the taper to be synthesized. 

A typical taper synthesis result obtained for 3413 elements array antenna positioned across a circular aperture using method A, is shown by the plots of the Taper Synthesis Gallery listed below.  The synthesized taper features three ring sectors with multilevel peak sidelobes and four rectangular nulling sectors. Complex weighting of the taper was used during its synthesis. The synthesized taper matches fully the user requirements and the final result was obtained after 6649 iterations.   

Synthesis Method B 

Method B is specifically intended for rectangular planar array antennas and can only be used to synthesize optimum amplitude-only tapers featuring linear Taylor like characteristics type or linear Bayliss like characteristics. A typical example is shown in the next Gallery. 

Synthesis Method C  

This method is developed for circular planar aperture aarray antennas. This method supports only the synthesis of amplitude-only tapers.

Plots showing the performance of the sum pattern on transmit with the taper synthesized for -65 dB peak sidelobe lobes. The shown results refer to a circular planar array antenna equipped with 2400 elements arranged in a square grid. The element distance is 0.5λ. The synthesis involved 1500 iterations and finished within 30 seconds. The shown results below are obtained using synthesis method C. 

Synthesis Method D 

Method D is mainly suited for planar array  antennas with a rectangular or elliptical aperture shape. Also this method supports only the synthesis of amplitude-only tapers.

The gallery below shows the synthesis results obtained for a small planar array antenna with an elliptical aperture shape and populated by 840 elements. The taper for the sum pattern on transmit is synthesized for -40 dB sidelobes in the horizontal main plane and -45 dB sidelobes in the vertical main plane.  The requirements were fully met.  Method D is presently under development. It is expected that this method will be part of APAS 1.085 which release is scheduled for the summer of 2016.    

Synthesis Method E

This method is primarily intended for planar array antennas having a non rectangular aperture shape. This taper synthesis method supports amplitude-only, phase-only and complex weighting and is exclusively based on multiple sector nulling.