Real-time imaging and wavevector analyses of radio waves incident to electromagnetic absorbers
Radio waves incident to electromagnetic absorbers have been experimentally visualized for the first time, which has been accomplished by the real-time visualization method for high-frequency electric field distributions: the live electrooptic imaging technique. Imaged have been electromagnetic reflections, refractions, and standing wave formations at sheet absorbers as well as gradual variations of wave fronts at a ravine plane of pyramidal absorber. Their wave properties have been clarified qualitatively as well as quantitatively by experimental mapped wave vectors.
Visualization of RF wave packets by live electrooptic imaging
An advanced concept for the visual observation of microwave signal propagations is proposed and demonstrated experimentally, where features of Fourier components included in a radio frequency (RF) wave packet are emphasized. The concept is based on the ultra-parallel measurement scheme in the space domain: the live electrooptic imaging technique. Theoretical explanation of the concept is given first and three possible procedures are discussed for its realization. Their characteristic features are also pointed out. Finally, results of experimental demonstrations for the concept are described with emphases on visualization of RF wave packets.
Hermetic sealing technique for F-band waveguides and packages
This paper presents a hermetic sealing technique for rectangular waveguides and packages to improve the reliability of systems in the F band (90–140 GHz). The technique features a new sealing structure, which is a laminate composed of two sealing plates and a spacer with a WR-8 waveguide. The sealing plate has the fused glass window and separates inside air from the ambient atmosphere. The laminated structure with the two sealing plates provides larger passband width than that with one sealing plate and is suitable for broadband wireless systems. The insertion loss of the fabricated sealing structure is 0.35 dB at 125 GHz. From 116 to 136 GHz, the return loss and a variation of group delay are better than 15 dB and 10 ps, respectively. We verified that the sealing structure has good simulation fidelity and that packages sealed with this technique meet the hermetic-seal standard in MIL-STD-883.