Broadband metal-dielectric near-field antenna
Klein, N., Lahl, P., Poppe, U., Kadlec, F., Kuzel, P
published in Journal of Applied Physics
98 (2005), 14910
Terahertz, spectroscopy, near-field imaging, pulsed broadband electromagnetic radiations, submillimetre wave antennas, submillimetre wave imaging, submillimetre wave spectroscopy, microwave photonics, dielectric materials
We present an antenna-based approach to near-field imaging and spectroscopy, which can be used for both continuous-wave and pulsed broadband electromagnetic radiations from microwave to terahertz frequencies. Our near-field antenna consists of a rectangular-shaped block of low-loss dielectric material sharpened to a pyramidal tip which is partially metallized and terminated by a micron-sized plane facet. At this facet the entire energy of the incident wave is concentrated as a very high but strongly localized electric field, which can be used as a sensitive near-field microprobe for electromagnetic radiation. Currently, experiments in reflection geometry with pulsed terahertz radiation and continuous-wave radiation near 80 GHz reveal a frequency-independent spatial resolution of about 20 µm corresponding to /200 at 80 GHz, which is only limited by the size of the facet terminating the tip.
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