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Nearfield anechoic chamber and farfield on-site antenna calibration pattern comparison of an S-band planar phased array radar

April 27, 2022
  |
Conference Paper
Author:
Christine F. Parry
…
Published in:
IEEE Annual Conf. on Wireless and Microwave Technology, WAMICON, 27-28 April 2022.
Topic:
antennas
R&D area:
R&D group:

Summary

The Advanced Technology Demonstrator (ATD) is an active, S-band, dual-polarization phased array radar developed for weather sensing. The ATD is an active electronically scanned array (AESA) with a 4-m aperture comprised of 4,864 individual transmit/receive (T/R) modules. The antenna was calibrated at the element, subarray, and array levels. Calibration, validation, and verification testing was completed in two main stages, first in an anechoic chamber and second after it was installed on site in its permanent location. This paper describes the procedure used to collect antenna patterns at each stage and compares three key performance metrics: beamwidth, mean-squared sidelobe level (MSSL), and integrated sidelobe level (ISL).
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Summary

The Advanced Technology Demonstrator (ATD) is an active, S-band, dual-polarization phased array radar developed for weather sensing. The ATD is an active electronically scanned array (AESA) with a 4-m aperture comprised of 4,864 individual transmit/receive (T/R) modules. The antenna was calibrated at the element, subarray, and array levels. Calibration, validation...

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Nearfield anechoic chamber and farfield on-site antenna calibration pattern comparison of an S-band planar phased array radar

Effect of a wet spherical radome on the reflected power for an S-band planar phased array radar antenna

October 24, 2021
  |
Conference Paper
Author:
Christine F. Parry
…
Published in:
2021 Antenna Measurement Techniques Association Symp., AMTA, 24-29 October 2021.
Topic:
antennas
R&D area:
R&D group:

Summary

An active S-band dual-polarized multifunction phased array radar (MPAR), the Advanced Technology Demonstrator (ATD), has recently been developed for weather sensing and aircraft surveillance. The ATD is an active electronically scanned array (AESA) with 4864 transmit/receive (T/R) modules and was installed in a spherical radome. Simulations and a novel phased array measurement technique have been explored to assess the impact of high reflectivity from a wet radome during rain that can potentially induce voltages exceeding the transmit amplifier breakdown voltage. The measurement technique uses array elements radiating one at a time to illuminate the radome, and uses superposition to quantify the received signal power in a reference antenna on the face of the array. It is shown that when the radome surface is wet and highly reflective, certain electronic steering angles sum to a large reflected signal focused on the array face. This measurement technique can be used prior to high-power phased array radar operation to monitor the magnitude of reflections and help avoid element transmit amplifier failures.
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Summary

An active S-band dual-polarized multifunction phased array radar (MPAR), the Advanced Technology Demonstrator (ATD), has recently been developed for weather sensing and aircraft surveillance. The ATD is an active electronically scanned array (AESA) with 4864 transmit/receive (T/R) modules and was installed in a spherical radome. Simulations and a novel phased...

READ MORE
Effect of a wet spherical radome on the reflected power for an S-band planar phased array radar antenna

HF vector sensor for radio astronomy: ground testing results

September 13, 2016
  |
Conference Paper
Author:
Mary Knapp
…
Published in:
AIAA Space 2016 Conf. and Exposition, 13-16 September 2016.
Topic:
sensors
R&D area:
R&D group:

Summary

The radio sky below ~10 MHz is largely unexplored due to the inability of ground-based telescopes to observe near or below the ionospheric plasma frequency, or cut-off frequency. A space-based interferometric array is required to probe the portion of the electromagnetic (E-M) spectrum below 10 MHz with sufficient angular resolution and sensitivity to be scientifically useful. Multi-spacecraft constellations scale quickly in cost and complexity as the number of spacecraft increases, so minimizing the number of required spacecraft for an interferometric array (while maintaining performance) is critical for feasibility. We present the HF (High Frequency, 3 to 30 MHz) Vector Sensor as a high performance spacecraft instrument in a future space-based interferometric array. The HF Vector Sensor is composed of three orthogonal dipoles and three orthogonal loop antennas with a common phase center. These six elements fully measure the E-M field of incoming radiation. We present the design of two prototype HF Vector Sensors, ground-based data collection at frequencies above the ionospheric cut-off, and imaging results using several different algorithms.
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Summary

The radio sky below ~10 MHz is largely unexplored due to the inability of ground-based telescopes to observe near or below the ionospheric plasma frequency, or cut-off frequency. A space-based interferometric array is required to probe the portion of the electromagnetic (E-M) spectrum below 10 MHz with sufficient angular resolution...

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HF vector sensor for radio astronomy: ground testing results

Vector antenna and maximum likelihood imaging for radio astronomy

March 5, 2016
  |
Conference Paper
Author:
Mary Knapp
…
Published in:
2016 IEEE Aerospace Conf., 5-12 March 2016.
Topic:
simulation
R&D area:
R&D group:

Summary

Radio astronomy using frequencies less than ~100 MHz provides a window into non-thermal processes in objects ranging from planets to galaxies. Observations in this frequency range are also used to map the very early history of star and galaxy formation in the universe. Much effort in recent years has been devoted to highly capable low frequency ground-based interferometric arrays such as LOFAR, LWA, and MWA. Ground-based arrays, however, cannot observe astronomical sources below the ionospheric cut-off frequency of ~10 MHz, so the sky has not been mapped with high angular resolution below that frequency. The only space mission to observe the sky below the ionospheric cut-off was RAE-2, which achieved an angular resolution of ~60 degrees in 1973. This work presents alternative sensor and algorithm designs for mapping the sky both above and below the ionospheric cutoff. The use of a vector sensor, which measures the full electric and magnetic field vectors of incoming radiation, enables reasonable angular resolution (~5 degrees) from a compact sensor (~4 m) with a single phase center. A deployable version of the vector sensor has been developed to be compatible with the CubeSat form factor.
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Summary

Radio astronomy using frequencies less than ~100 MHz provides a window into non-thermal processes in objects ranging from planets to galaxies. Observations in this frequency range are also used to map the very early history of star and galaxy formation in the universe. Much effort in recent years has been...

READ MORE
Vector antenna and maximum likelihood imaging for radio astronomy
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