Abstract
In this study, photonics-based near-field measurement and far-field characterization in a 300-GHz band are demonstrated using an electrooptic (EO) sensor with planar scanning. The field to be measured is up-converted to the optical domain (1550 nm) at the EO sensor and delivered to the measurement system with optical fiber. The typical phase drift of the system is 0.46° for the one-dimensional measurement time of 13 s, which is smaller than the standard deviation of the phase measurement of 1.2° for this time scale. The far-field patterns of a horn antenna calculated from the measured near-field distribution are compared with that measured with the direct far-field measurement system using a vector network analyzer. For the angular related parameters, the accuracy of the results obtained by our near-field measurement are comparable to that of those obtained by direct far-field measurements. The sidelobe level discrepancy (approximately 1 dB) between the results obtained based on our near-field measurement and those from the direct far-field measurements are attributed to the excess noise of the probe correction data. We believe that photonics-based near-field measurements with spherical EO probe scanning will pave the way for the characterization of high-gain antennas at the 300-GHz band.
Highlights
I N recent years, the development of antennas operating in the upper limit of the millimeter-wave band or the lower limit of the terahertz (THz) band has become increasingly important due to the increasing need for high-capacity and -speed wireless communications in these frequency bands
Our system has the following features over conventional systems: (1) the probe head is small, and all the components, including the optical fiber, are made of dielectric material; the field disturbance to be measured is negligible; (2) the probe head is extremely light; the deflection of the scanner that holds the probe is negligible, enabling a high-fidelity pattern measurement; (3) the detected signal is transmitted to the measurement system via flexible and low-loss optical fibers; the system can accommodate large scan areas; and (4) the local oscillator (LO) signal is generated based on the photonics-based self-heterodyne technique [25], and the RF signal is detected based on a nonpolarimetric frequency downconversion technique [26], which is more stable than the conventional polarimetric technique [27]
We demonstrated the near-field measurement (NFM) and the far-field characterization at the 300-GHz band based on the photonicsbased system using the EO probe
Summary
I N recent years, the development of antennas operating in the upper limit of the millimeter-wave band or the lower limit of the terahertz (THz) band has become increasingly important due to the increasing need for high-capacity and -speed wireless communications in these frequency bands. Our system has the following features over conventional systems: (1) the probe head is small (submillimeter order), and all the components, including the optical fiber, are made of dielectric material; the field disturbance to be measured is negligible; (2) the probe head is extremely light; the deflection of the scanner that holds the probe is negligible, enabling a high-fidelity pattern measurement; (3) the detected signal is transmitted to the measurement system via flexible and low-loss optical fibers; the system can accommodate large scan areas; and (4) the local oscillator (LO) signal is generated based on the photonics-based self-heterodyne technique [25], and the RF signal is detected based on a nonpolarimetric frequency downconversion technique [26], which is more stable than the conventional polarimetric technique [27] It can cover several hundreds of GHz frequency band with a high phase detection accuracy without changing the EO probe head [28]– [31]. The results suggest that accurate radiation patterns can be measured by the NFM system without any probe correction if spherical scanning is used
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
