characterization of extreme weather phenomena. Data and results from the APAR platform will lead to better forecasting and estimation of heavy precipitation and potential economic impacts for the nation. APAR is a dual-polarized active electronically scanned array (AESA) antenna consisting of several thousand of individually controlled radar elements mounted on the National Science Foundation (NSF)/NCAR C-130 scientific research aircraft. NCAR generated a set of AESA requirements to ensure APAR mission success. UCAR/NCAR has funded Ball Aerospace to develop the AESA subsystem that can be both manufacturable and cost effective, and that will remain scientifically relevant over the intended 20 year lifetime of the APAR system.
The APAR AESA development program can be divided into three main phases: the preliminary design review (PDR) phase of yesterday, the critical design review (CDR) phase of today, and the AESA fabrication, test and calibration of tomorrow.
There were two efforts within the PDR phase of the AESA development program, with the “schematic design” effort running from July 2020 to December 2020 and the final “PDR effort” running from March 2021 to August 2021. The “schematic design” effort concentrated on top-level design for the AESA subsystem. This phase involved trade studies that produced requirements on array performance, prime power, size and weight, and cooling. These requirements resulted in a subsystem architecture that included components such as the radiating system and support structure, RF electronics, array control units (ACU), digital receiver exciters (DREX), AESA cooling system (ACS) and power distribution system (PDS). The end of this program resulted in a PDR-level design package that forms the basis for the CDR phase.
Today, the APAR program is in its CDR phase, which started in June 2023. The first major milestone is the development, construction and delivery of a prototype subarray panel or SAP together with design documents for the full AESA. At the end of this phase, the AESA subsystem will be at a CDR level and will be ready for procurement. The Ball team is currently performing system engineering to define and flow down requirements to individual subsystems. The team has been working on specification decomposition, calibration procedures and verification testing plans to ensure that the system meets the demanding requirements of weather radar. There will be two iterations of the SAP design to ensure high performance, manufacturability, and reliability. This phase of the program started in mid-June of 2023, and is expected to continue through the end of 2024. Details of the current status will be provided.
The future procurement phase of the APAR AESA program involves construction, testing and delivery of first one and then three additional AESA panels, with associated electronics, cooling and support equipment. Attention will be paid to the identification and early procurement of long lead time parts, and parallel construction schedules to meet the program timeline. This phase will see the performance full AESA subsystem performance measurements. There is also interest from NOAA for the APAR system for their Hurricane Hunter fleet.
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