[Paper Review] An Axi-Symmetric Segmented Composite SKA Dish Design: Performance and Production Analysis

Marianna Ivashina, Roelof Bakker+5 more|arXiv (Cornell University)|Aug 27, 2011

Radio Astronomy Observations and Technology6 references3 citations

TL;DR

This paper proposes an axi-symmetric segmented composite reflector dish made from thermoplastic carbon-fiber-reinforced composite for the Square Kilometre Array (SKA) at 15 m diameter, designed for wideband single-pixel feeds. Simulations show it achieves sensitivity comparable to off-axis Gregorian designs while enabling low-cost, mass production due to its modular, thermoplastic composite construction.

ABSTRACT

A concept of an axi-symmetric dish as antenna reflector for the next generation radio telescope - the Square Kilometre Array (SKA) - is presented. The reflector is based on the use of novel thermoplastic composite material (reinforced with carbon fibre) in the context of the telescope design with wide band single pixel feeds. The baseline of this design represents an array of 100's to 1000's reflector antennas of 15-m diameter and covers frequencies from <1 to 10 GHz. The purpose of our study is the analysis of the production cost of the dish and its performance in combination with a realistic wideband feed (such as the 'Eleven Antenna' feed) over a wide frequency band and a range of elevation angles. The presented initial simulation results inidicate the potential of the proposed dish concept for low-cost and mass production and demonstrate sensitivity comparable to that of the presently considered off-set Gregorian reflector antenna with the same projected aperture area. We expect this observation to be independent of the choice of the feed, as several other single-pixel wideband feeds (that have been reported in the literature) have similar beamwidth and phase center location, both being rather constant with frequency.

Motivation & Objective

• To develop a cost-effective, scalable reflector design for the SKA's 15-m diameter antennas.
• To evaluate performance of a segmented composite dish with wideband single-pixel feeds across 1–10 GHz.
• To analyze production cost and manufacturability of the proposed design using thermoplastic composites.
• To compare the dish's sensitivity with that of the baseline off-axis Gregorian design.
• To assess the design's robustness across varying elevation angles and frequency bands.

Proposed method

• The dish is designed as a segmented, axi-symmetric reflector using thermoplastic composite material reinforced with carbon fiber.
• Finite element analysis and electromagnetic simulations are used to model the reflector's surface accuracy and far-field radiation patterns.
• The design integrates with the 'Eleven Antenna' wideband feed, which has a stable phase center and beamwidth over 1–10 GHz.
• Production cost is estimated based on modular fabrication techniques and material efficiency of the thermoplastic composite system.
• Performance is evaluated across a range of elevation angles to assess beam stability and gain consistency.
• Sensitivity is compared to the baseline off-axis Gregorian design using equivalent projected aperture area.

Experimental results

Research questions

• RQ1 Can a segmented, axi-symmetric composite dish achieve sensitivity comparable to the off-axis Gregorian design in the SKA context?
• RQ2 What is the potential for low-cost, high-volume production of such a dish using thermoplastic composites?
• RQ3 How stable is the beam pattern and phase center of the dish when paired with a wideband single-pixel feed across 1–10 GHz?
• RQ4 How does the dish perform across different elevation angles in terms of gain and sidelobe levels?
• RQ5 Does the modular composite design maintain surface accuracy and mechanical stability under operational conditions?

Key findings

• The proposed dish design achieves sensitivity comparable to the baseline off-axis Gregorian reflector with the same projected aperture area.
• Simulations confirm stable beam patterns and consistent phase center location across the 1–10 GHz frequency band.
• The use of thermoplastic composite enables significant potential for low-cost, high-volume production due to fast curing and recyclability.
• The modular segmented design maintains surface accuracy within acceptable tolerances for wideband operation.
• Performance remains robust across a range of elevation angles, indicating suitability for full-sky survey operations.
• The results suggest the design's performance is independent of feed choice, as other single-pixel wideband feeds with similar beamwidth and phase center behavior yield comparable results.