POS version 6 released!

A total makeover has made the POS look-and-feel similiar to GRASP. This represents a major break-through in the user-friendliness and efficiency of the program, just as it ensures compatibility with the new GRASP project structure. The user already familiar with GRASP can therefore easily understand the interface, while newcomers will find the learning curve very short, assisted by a library of already-solved cases that reflect many of the conceptually different applications of POS. Needless to say, new projects are readily exchanged between POS and GRASP.

GUI features

In addition to being modern and inviting, the GUI provides an intuitive way to control antenna parameters. All antennas and feeds are accessible by selecting the component on the drawing, and users of the previous version will be glad to see that the object editor for e.g. a reflector, now also provides access to all referenced objects, e.g. coordinate systems, rims etc.

On start-up the user is presented with a choice of options, including launching the auxillary program COBRA, which is still “old-school” but provides the antenne designer with a convenient tool to define coverages on earth as seen from space, and subsequently generate a POS project. It is also possible to select worked-out examples from a library that includes. amongst other, single-feed single shaped reflector, direct-radiating array and shaped reflector with feed array.

Automatic convergence estimate for PO

The well-proven GRASP method of estimating the appropriate density of the PO current sampling is now available to the POS user as well. It is a long-awaited feature in POS, and particularly useful since, for highly-shaped reflectors, it is not “just” the aperture size and the location of the file points that influence the integration; also the shaping itself has an effect and all fine details must be captured in the PO integral.

Least-squares optimization

We have added a least-squares optimizaton engine to POS, creating an alternative design feature that may allow better average performance of a contoured-beam antenna while not fulfilling the optimizaiton goals on e.g. the edge of coverage. To achieve this, the choice of algorithm is a one-sided least squares, such that only stations where the goals have not been achieved are included in the sum-of-squares.

Other enhancements:

• Individual calculation of the optimized field for each optimization task, with the choice of different grid-types than the standard (u,v) and various polarization options
• Individual selection of Zernike modes as expansion functions, such that the modes are not tied to a specific range in the m- and n-indices
• More general selection of edges for which PTD is calculated, resulting in improved compatibility with GRASP