Some applications, such as space-based radar, require wide-angle scanning and very narrow beamwidths Hybrid antennas, which are reflector antennas fed by arrays, may provide an alternative to the use of large array antennas in these applications This paper presents a numerical method for shaping the reflector to maximize the collected energy over the desired scan range By experimenting with various feed array sizes and shapes, and using the methods presented herein to find the optimal reflector shape at each step, one may arrive at designs that minimize the feed array surface area while meeting various system design objectives such as scan range, aperture size, and aperture utilization Optimization examples are provided for several feed array configurations, along with analyses of the resulting performance over the desired scan range

Wide-angle scanning with reflector antennas: a new design technique

A Windows application for the analysis and synthesis of reflector antennas is presented. AntLab for Windows uses a fast physical optics algorithm in a graphical environment. This method presents a high degree of accuracy and spends little time, which is a key factor in a real designing process. © 1999 John Wiley & Sons, Inc. Comput Appl Eng Educ 7: 23–29, 1999

Educational software for single- and dual-reflector antennas

This paper presents a new approach to beamforming in hybrid antennas. Using a scattering matrix model for the hybrid antenna system, a bidirectional transformation is developed that relates the signals at the hybrid system feed to the signals that would be present in a planar array at the location of the reflector aperture. For example, the received fields at the feed of a hybrid antenna system may be transformed into the fields at the reflector aperture, and these reflector aperture fields may then be processed as if they were received by a planar or linear array. Similarly, the desired field or current distribution across the reflector aperture when transmitting may be transformed into the required field or current distribution at the hybrid system feed. This method allows standard linear or planar array analysis and synthesis techniques to be used with the hybrid system. Examples are provided for transmit and receive weight synthesis.

A scattering matrix-based beamformer for wide-angle scanning in hybrid antennas

A new reflector shaping technique to improve the beam scanning capability of hybrid antennas (i.e., a reflector system illuminated by a phased array) is presented. Errors between the desired scan directions and the outgoing rays' directions in the scanning range are minimized by adjusting the reflector shape. This technique can be used to decrease the active element number of the feed array during the antenna scans, or reduce the gain loss caused by beam scanning when the number of active elements is given. An offset reflector antenna system is designed and analyzed, through which the validity of the technique is demonstrated.

A novel shaping design technique for the reflector in hybrid antennas

Three different reflector antenna solutions for reception of multiple satellite DBS signals are presented and compared. The first solution is based on lightly over-sizing and shaping the surface reflector. The second one consists of using two feed arrays. The last solution proposes a feeding system based on two subreflectors.

Reflector antenna solutions for multisatellite DBS reception

A scanning dual-offset reflector antenna using the simple motion of a flat subreflector to illuminate different parts of a shaped main reflector is presented. A particular case having a 20-degree linear field-of-view (for a DBS application) with a 30/spl lambda/ aperture diameter is explored. The main reflector surface is shaped to minimize the phase aberrations across the field-of-view. Once the main reflector surface is designed, the subreflector parameters are determined to ensure optimum focusing across the field-of-view. >

M.E. Lorenzo

Papers

A shaped dual-reflector antenna with a tilting flat subreflector for scanning applications