# Compact First-Order Probe for Spherical Near-Field Antenna Measurements at Low Frequencies

Oleksiy S. Kim

Research output: Contribution to journalJournal articleResearchpeer-review

## Abstract

Guidelines for designing compact and lightweight first-order probes for spherical near-field antenna measurements at frequencies below 1 GHz that exploit first-order properties of electrically small self-resonant radiators combined into superdirective endfire arrays are established theoretically, exemplified numerically, and validated experimentally. A prototype of the probe designed to operate at a central frequency of 435 MHz exhibits the impedance bandwidth of 15 MHz with a directivity of more than 9 dBi and parasitic $|\mu |\ne 1$ spherical modes suppressed to at least −42 dB. The probe height is just 343 mm above a 720-mm circular ground plane and weighs about 5 kg.
Original language English I E E E Transactions on Antennas and Propagation 65 7 3684 - 3690 0018-926X https://doi.org/10.1109/TAP.2017.2700051 Published - 2017

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## Keywords

• Probes
• Bandwidth
• Antenna measurements
• Antenna arrays
• Frequency measurement
• Dipole antennas
• Electrically small antennas
• Frequency bandwidth
• Linear arrays
• Physical bounds
• Quality factor