Raytheon Polarimetric X-Band Phased Array Radar: Single and Netted Radar System

Raytheon is in the development and test phase of a low cost Polarimetric X-Band Active Phased Array pencil beam radar (RXPAR) solution that is capable of both target and weather detection, and which incorporates Raytheon's product line ASR (Air Surveillance Radar) radar processing, wind turbine mitigation processing, and enhanced tracking, combined with advanced weather processing features developed under the National Science Foundation sponsored Collaborative Adaptive Sensing of the Atmosphere (CASA) program. The basic building block for the RXPAR is an active front-end based on a modular sub-array architecture. This air-cooled assembly utilizes a SiGe chip-set to achieve T/R functionality at nominal 70 mW per radiating element, and each T/R channel has independent phase and amplitude control. The dual-polarization radiating element at each T/R channel has gain and cross-polarization performance selected from a market and technology assessment of available options. 128 T/R channels are incorporated into a single Line Replaceable Unit (LRU) and multiple LRUs are arranged into arrays transmitting tens of watts average power. The array length and height can be altered between 50 cm and 1.5m by changing the number of LRUs.

The RXPAR has a maximum operational range of nominally 30km, an azimuth electronic scan capability of ±45º, and an elevation electronic scan capability of ±15º. This radar is designed to be operated in a network environment using wireless links, and can be mounted on existing infrastructure such as mobile phone towers, turbine structure, or buildings. It outputs standard ASTERIX (aircraft tracker) and NetCDF4 (weather products) data formats that can be merged with radar data of any other radar type.

Among many customer and CRADA (Cooperative Research and Development Agreement) based demonstrations used to evaluate the system capabilities in 2013 and 2014, our RXPAR supported wind turbine mitigation testing during the April 2013 U.S. Interagency Field Tests and Evaluation Trials (IFTEs) conducted by MIT/Lincoln Laboratory and Sandia National Labs on behalf of the DoD, DHS, DoT/FAA, and DoE (NOAA). The IFTEs are designed to evaluate selected technologies or approaches for mitigation of wind turbine interference. The evaluation demonstrations have not been limited to single radar array, Raytheon deployed a network of two radars with a single array panel each in the Dallas Fort-Worth region with the goal of evaluating radar overlap performance in the context of hard target detection and weather phenomenon collection.

In October 2014, tests will be conducted using the radar to detect wake vortex of aircraft approaching Boston Logan International airport in conditions of light rain. High temporal and spatial resolution X-band data and the use of specific design waveforms can provide improved detection of vortices in this type of weather. Test conduct description and results will be included in the presentation.

Networking together a cluster of these radars in an asynchronous multi-static adaptive collaborative manner provides coverage out to significantly longer ranges, offering a straightforward path to migrate the medium range non-cooperative Primary Surveillance Radar (PSR) mission to X-band. Raytheon has been developing the concept of a Netted X-band, a network of Raytheon X-band Phased Arrays, to simultaneously perform both weather and air surveillance functions, thereby addressing the missions of multiple agencies using a common infrastructure.

The RXPAR is designed to address multi-missions in a low cost, low profile package. This paper will discuss the system architecture of both the standalone radar and netted radar systems. Specific test case examples of the standalone and netted radar demonstration data will be presented. A companion paper details the advantages of a distributed multi-panel system operation in comparison to a large long range radar for the retrieval of high resolution, fast update, vector wind and dual polarization retrieval.