Antenna characterization techniques are often expensive and time-consuming. NASA’s Glenn Research Center developed a highly versatile and automated system to perform characterization of single or multiple small circuit antennas, printed on-wafer or on other substrates, by measuring the antenna’s near-field radiated power.
This technology is designed specifically for the fast characterization of miniaturized printed circuit (MPC) antennas fabricated on dielectric, semiconductor, or membrane substrates. It also characterizes active antennas that are difficult to test in traditional antenna-testing ranges because of the antennas’ relative fragility or small size, the severity of direct current bias, or the test-fixture requirements. This break-through allows users to analyze data obtained from near-field characterization to determine the antenna’s far-field properties and optimize the performance of the antenna system.
In this scanner system, radio-frequency (RF) signals and DC-biased voltages and currents are supplied to an antenna under test (AUT) through an RF feed and DC probe that are integrated into the system. The mechanisms for scanning the open-ended waveguide probe are a three-axis slide mechanism and a rotation mechanism that, under computer control, positions this probe to acquire data at prescribed grid points on a plane very close to the AUT. This near-field scanning scheme eliminates the need for special fixturing. It captures a maximum amount of energy radiated by one or multiple small antennas while they are DC-biased.
Glenn’s desktop-sized scanning system makes data acquisition and analysis easy. The system is controlled by user-friendly commercial software. The user has great control of the system, with the dimensions of the near-field scan area and the distance between grid points specified by the user. After each scan, the data analysis software processes the measurement data and displays the far-field radiation pattern of the AUT, computed from the near-field measurements. With minor modifications, the system can also be adapted for far-field measurements, as well as for diagnostic and imaging applications.