A Low-Scattering Pixelated Dielectric Rod Waveguide Probe for Near-Field Measurement

A 3.4-3.7 GHz dielectric rod waveguide probe for near-field measurements is proposed for applications on the 5G sub-6 GHz band. By implementing a dielectric-filled waveguide, the probe achieved a higher resolution and low scattering characteristics through a miniaturized aperture compared to the open-ended waveguide (OEWG) used for conventional near-field probes. An 8\times 8 pixelated grid structure in the dielectric launcher section of the probe is implemented to further reduce the scattering characteristics of the probe. The proposed probe is fabricated and experimentally verified. A coating of silver is applied to the dielectric during a production process. Measurement shows that the -10 dB reflection coefficient bandwidth meets 3.4-3.7 GHz requirement and that the radiation pattern shows a broadside gain of about 3.8 dBi with no null at the forward hemisphere. The results of a scattering characteristic experiment indicate decreased interferer level of 7.3 dB compared to an OEWG.