UK SBS SSAPS18140 CASTR System Validation Monopulse Detailed Design Study

***PLEASE NOTE THIS IS AN AWARD NOTICE, NOT A CALL FOR COMPETITION*** The STFC Chilbolton observatory operates a 25m prime focus reflector antenna in a meteorological radar system. There are increasing requirements to upgrade the radar to enable satellite tracking by implementing monopulse operation in addition to maintaining the weather radar functionality; this requires a new feed to be developed.

The objective of this study is to devise a practical monopulse feed structure given a limited available space around the current feed. The available space may be approximately bounded by a cylinder of diameter 450 mm and depth approximately 1500 mm.

The feed should feature dual orthogonal linear polarisations in the sum patterns and the difference patterns sets in azimuth and elevation. The reflector antenna is a non-offset prime focus antenna with dish diameter of 25m and f/D ratio of 0.36.

The antenna, including feed structure, is intended for both transmit and receive, with a maximum transmit mean power (input to the structure) of 800 W and a maximum transmit peak power of 100 kW. Current frequency of operation is 3.0765 GHz, but there is a desire to operate between 2.7 GHz and 3.5 GHz.

The contractor is required to: - Identify the optimal feed system to meet the above requirements and simulate the field patterns for the sum beam and error beams from the feed. - Simulate the feed with the 25m diameter reflector and show the resulting sum beam and error beam patterns and gains. This shall include calculations of the output signals from the receive ports for targets off boresight to at least ±0.1 degrees, ideally out to the point where the sum beam is 10dB down on the boresight gain. - Fabricate a prototype of the feed elements. - Test and the measure results compared with the simulations.

Any differences shall be described and where the performance does not meet the requirements an approach to correct the design shall be suggested. This contract has been awarded in alignment with PCR 32 (2) (a)where no tenders, no suitable tenders, no requests to participate or no suitable requests to participate have been submitted in response to an open procedure or a restricted procedure, provided that the initial conditions of the contract are not substantially altered and that a report is sent to the Commission where it so requests;