77 GHz passive millimeter wave (PMMW) imaging camera for the purpose of security is developed. In order to detect
concealed objects in clothes without hindrance to flow of people at airport security checks, video rate imaging is realized
using one-dimensional imaging sensor array of 25 elements and a flapping reflector. As receiving antennas, novel
antipodal Fermi antenna (APFA) having required characteristics for passive imaging such as broad bandwidth to obtain
enough power, axially symmetric directivity with 10dB beam width of 35 degrees to obtain optimum coupling with
dielectric lens, narrow width geometry for high spatial resolution of imaging is used. Real-time calibration (RTC)
technique is introduced to eliminate the drift of receiving circuits. Interpolation technique to improve the quality of
image and marking software for screening of suspicious objects are also developed. High spatial resolution of 20 mm is
obtained by using developed imaging camera.
Passive millimeter wave (PMMW) imaging systems have been developed at Ka-band using imaging elements with Fermi tapered slot antennas (TSA) with corrugation. The imaging elements were installed in a focal-plane imaging system and a Fresnel (close)-distance imaging system to obtain medical and bio-object images.
Optical characteristics of a circular photonic crystal (CPC) in the frequency range of 0 to 20 GHz were investigated. The sample was made by alumina rods of 2 mm in radius and 300 mm in length. The alumina rods were arrayed in the form of concentric circles with 6-fold symmetry. The transmission spectra were calculated at various radical distances. When the radical distance was 8 mm, a photonicgap was obtained around 12 GHz. The experimental results were in good agreement with the calculations. Although the lattice positions were shifted from the ones of the CPC, the same transmission spectrum was obtained in the phase-shifted CPC. Phase-shift is a useful means for eliminating translational symmetries that would often appear in the exterior part of a CPC composed of numerous concentric circles. Isotropic photonicgaps were obtained for both a CPC and the phase-shifted CPC.
Conference Committee Involvement (1)
Device and Process Technologies for Microelectronics, MEMS, and Photonics
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