Abstract:Abstract-An advanced aspheric and asymmetric large aperture dielectric lens antenna is proposed firstly here for high resolution at Wband frequency. Large aperture and aspheric lens provides minimum focusing error and high resolution in millimeter wave quasi-optics application. To the best of the authors' knowledge we design first time 500 mm large aperture lens for W-band quasi optics application. Near field radiation pattern, beam size and focal length of the lens are obtained theoretically and experimentall… Show more
“…Many authors have demonstrated their design theories and experiment results of lens antenna for various applications [6] [7]. In this paper, the design of a W-band quasi optical lens antenna for short-range passive imaging is presented.…”
A quasi-optical dielectric lens used for W-band focal plane array passive imaging has been developed. The imaging system requires the lens to form beam spot with 3 dB width less than 35 mm at distance of 3500 mm. The powerful optical design software ZEMAX was utilized to design the contours of the lens, and numerical method based on ray tracing and Huygens' Principle was processed to verify the design result. Measurement result shows that the 3 dB width of the beam spot formed by the lens is 34 mm at distance of 3460 mm, and the beam pattern on imaging plane are equally arranged and the intensity decreases only 0.55 dB while the object lateral deviation increases to 300 mm.
“…Many authors have demonstrated their design theories and experiment results of lens antenna for various applications [6] [7]. In this paper, the design of a W-band quasi optical lens antenna for short-range passive imaging is presented.…”
A quasi-optical dielectric lens used for W-band focal plane array passive imaging has been developed. The imaging system requires the lens to form beam spot with 3 dB width less than 35 mm at distance of 3500 mm. The powerful optical design software ZEMAX was utilized to design the contours of the lens, and numerical method based on ray tracing and Huygens' Principle was processed to verify the design result. Measurement result shows that the 3 dB width of the beam spot formed by the lens is 34 mm at distance of 3460 mm, and the beam pattern on imaging plane are equally arranged and the intensity decreases only 0.55 dB while the object lateral deviation increases to 300 mm.
“…When compared with active imaging, MMW radiometric imaging does not radiate any form of radiation, and it offers the advantages of imaging covertly, eliminating specular effects and avoidance of interference with other systems [2]. Additionally, due to the superior capability of imaging through natural and manmade obscurants, MMW radiometric imaging has attracted increasing attention in broad areas ranging from precise guidance to concealed contraband detection [3][4][5][6][7].…”
Abstract-The existence of reverse radiation noise in the millimeterwave (MMW) radiometric imaging system with a superheterodyne receiver seriously affects the imaging experiments carried out at short range, thus leading to the degradation of MMW radiometric images and difficulty in recognizing targets. Based on the generation mechanism of reverse radiation noise, the specific influence on imaging for relative radiometry is investigated in this paper, and some methods of eliminating or reducing this noise are proposed. Then, two series of comparative imaging experiments are conducted with a 3 mm band radiometric imaging system. Both theoretical analysis and experimental results are presented to validate the actual existence of interference-like stripes imposed by the reverse radiation noise. Moreover, it is proved that adopting an isolator in the MMW receiving front-end can effectively reduce the reverse radiation noise and significantly improve the imaging performance.
“…For instance, small bandwidth of high-order mode dielectric [9,10] and microstrip patch antennas [23,24] can constrainedly meet the lowest requirements of the 60-GHz WLAN. Although there are also wideband operations reported, they are limited by either the bulky dimensions [12,25,26] or omni-directional radiation patterns [27].…”
Abstract-Although many directive antennas operating in a narrow band of millimeter (mm) waves were reported, e.g., antennas for 60-GHz wireless local area network (WLAN), their wideband counterparts are still unpopular. Cavity-backed antennas (CBAs) are widely developed and reported in microwave frequency bands, but handful of literatures can be found about mm-wave CBAs in spite that their many properties are quite suitable for mm-wave applications. This paper presents a wideband unidirectional CBA with a bowtie exciter, operating in a frequency band of 40 ∼ over 75 GHz, and it is carefully analyzed in terms of influences of all components on the radiation patterns, broadside gains, and reflection coefficients of the proposed antenna. Then, the antenna prototype is built by generic printed circuit board (PCB) technologies, and measurements prove the validity of simulations.
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