Millimeter-wave near-field antenna measurements

Paula Irina Muntianu

Research output: Book/ReportPh.D. thesisResearch

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Abstract

A 60 GHz first-order dual-polarized probe for spherical near-field antenna measurements based on a switch has been developed and antenna diagnostics for a Standard Gain Horn (SGH) were investigated at 60 GHz. In millimeter-wave near-field antenna measurements, first-order dual-polarized probes possess several advantages over other types of probes. In particular, they ensure an accurate and efficient near-field to far-field transformation scheme using only one full-sphere scan of the antenna under test (AUT). A dual-polarized probe based on a 27 dB gain conical horn, an Orthomode Transducer (OMT) operating in the 50-75 GHz frequency range and a SPDT (Single Pole Double Throw) switch working in the 600 MHz-67 GHz frequency range has been developed. The probe components were individually tested. The OMT and switch show measured values better than 40 dB for the isolation. The probe was designed to have a high gain, in order to compensate for the high path loss at 60 GHz, which is 83 dB for a 6 m distance. The probe was calibrated at DTU Planar Near-Field (PNF) Facility and DTU-ESA Spherical Near-Field Antenna Test Facility including pattern, polarization and channel balance calibration. In general, the dual-polarized probe shows a high performance at 60 GHz. The calibration process is challenged by the sources of uncertainties, which at 60 GHz become more significant. The dual-polarized probe was tested as a probe for the measurement of a SGH and of a 60 GHz offset dual-reflector antenna. It was found that the co-polar component of the tested antennas show results in good agreement with reference measurements. It was noted, that the switch contributes to the dynamic range reduction and affects the low radiation patterns levels of the tested antennas. Overall, it was shown that accurate dual-polarized probe measurements can be conducted, but they are challenged by the switch technology at 60 GHz.
An investigation on antenna diagnostics at 60 GHz was conducted for a 25 dB SGH. This includes the magnitude and phase of three rectangular components of the electric and magnetic fields, as well as Poynting’s vector components obtained from the DTU PNF setup without external frequency conversion. The aperture fields and power flow are computed by Inverse Fourier Transforming (IFT) the Plane Wave Spectrum (PWS), which is obtained from the complex measurement of the radiated near-field. It was found that the diagnostics results are affected by physical effects. The results showed, that the magnitude and phase and also the Poynting’s vector components contain additional information of the aperture field. The research addressed the challenges to conduct 60 GHz accurate dual-polarized probe spherical near-field measurements as not so much experience exists on this topic. The work also concerned, the investigation of antennas diagnostics at 60 GHz for quantities not exploited previously.
Original languageEnglish
PublisherTechnical University of Denmark
Number of pages152
Publication statusPublished - 2020

Projects

Millimeter-wave Near-Field Antenna Measurements

Muntianu, P. I., Breinbjerg, O., Breinbjerg, O., Arslanagic, S., Sierra-Castaner, M. & Le Coq, L.

Technical University of Denmark

15/11/201412/08/2020

Project: PhD

Cite this

Muntianu, P. I. (2020). Millimeter-wave near-field antenna measurements. Technical University of Denmark.