The introduction of ESAs enables the exploration and enhancement of a wide variety of electromagnetic applications and missions. These applications range from broadband communications, high-resolution imaging, radar, and the cognitive multifunction domain of electronic warfare.

Modern electronically scanned arrays—including passive ESAs (PESA), active ESAs (AESA), and digital beamformers—are designed modularly with fundamental components, such as Power Amplifiers (PAs) and Transmit and Receive Modules (TRMs). The performance of these components in all environments ensures system performance, minimizes the likelihood of system downtime, and enables mission readiness.

The following figure shows a typical PESA block diagram. Through programming each element with a frequency-dependent phase offset, the individually delayed signals result in a directionally steered wavefront.

Component Characterization—Components characterization requires many RF measurements—such as Power-Added Efficiency, Noise Figure, S-parameters, Compression, Noise Figure, and others— that verify whether the device has the parameters necessary to perform in the system. The measurement also verify that the production is able to fabricate the device with the specifications. You can obtain these measurements with RFmx modules or using specific measurement libraries depending on the purpose, such as Power-Added Efficiency Measurement Library or S-Parameter Measurement Library.

Note Refer to Spectral Measurements Concepts in the RFmx SpecAn User Manual for more information about measurements available through RFmx modules.

Module Measurements—Module measurements require the use of many RF channels simultaneously controlled and coordinated with power supplies and measurement units or instruments. Obtain these measurements with trigger signals, shared Local Oscillators, and direct connection to the device for setup or state control.

Subsystem Validation—A subsystem is a collection of RF elements that can be discrete or, as is more common, integrated into one device like the Monolithic Microwave Integrated Circuit (MMIC) or Radio Frequency Integrated Circuits (RFIC).

Testing those devices require the use of digital interfaces for programming and extracting the stream of I/Q data to the device. Also, it requires indirect measurements with the intention of characterizing the RF features or end effect of the device.

To test these components, modules, or systems, the ESA Characterization Reference Architecture builds on the NI platform by incorporating the following:

• NI hardware
• Off-the-shelf measurement libraries for general use, such as RFmx Pulse or RFmx Noise Figure
• Software libraries designed to evaluate specific measurements for pulsed RF signals, such as Power-Added Efficiency or S-Parameters with external couplers

Key Features

The ESA Characterization Reference Architecture performs the following measurements:

• Pulse profile and pulse stability measurements
• Two-port S-parameter measurements
• Power-added efficiency (PAE) measurements
• Compression point (PxdB) measurements
• Gain over frequency (flatness, variation)
• Noise figure measurements
• Phase noise measurement
• Third-order Intercept (TOI)
• Many other measurements

In addition to those measurements, ESAs support digital TRMs that allow communication with the device using a digital link. The ESA can use the Digital Signal Transceiver (DST) Driver to implement generation and acquisition of I/Q signals using a similar interface used in NI-RFSG and NI-RFSA. Then, you can use the measurements for your characterization.