# Optimal subreflector position determination of shaped dual-reflector antennas based on the parameters iteration approach

## TL;DR

This paper introduces an iterative parameter method to accurately determine the optimal subreflector position in shaped dual-reflector antennas, enhancing electromagnetic performance under gravity distortion.

## Contribution

It presents a novel iterative approach combining optical path difference and electromagnetic modeling to optimize subreflector positioning in shaped Cassegrain antennas.

## Key findings

- Improved electromagnetic performance after subreflector adjustment.
- Rapid numerical solution for optimal subreflector parameters.
- Effective enhancement demonstrated on a 25 m shaped Cassegrain antenna.

## Abstract

A new method based on parameters iteration technique has been developed to determine the optimal subreflector position for shaped Cassegrain antennas to improve the electromagnetic (EM) performance distorted by gravity. Both the features of shaped surface and the relationship between optical path difference (OPD) and far field beam pattern are employed. By describing the shaped dual-reflector surface as a standard discrete parabola set, we can utilize the optical features of the standard Cassegrain system in the classical OPD relationship. Then, the actual far field beam pattern is expressed as the synthesis of ideal beam and error beam by decomposing subreflector adjustment parameters using mechanical-electromagnetic-field-coupling-model (MEFCM). Furthermore, a numerical method for determining optimal subreflector position is presented. The proposed method is based on the iteration technique of subreflector adjustment parameters, and the optimal far field pattern is used as the iteration goal. The numerical solution of optimal adjustment parameters can be obtained rapidly. Results of a 25 m Shaped Cassegrain antenna demonstrate that the adjustment of the subreflector to the optimal position determined by the proposed method can improve the EM performance effectively.