A Fast Method for Image Mosaicing Using Geometric Hashing

The general problem of mosaicing is to create a single seamless image by aligning a series of spatially overlapped images. The result is an image with a field of view greater than that of a single image. Traditionally this research has been aimed at stitching together images taken by aerial or satellite reconnaissance equipment. With the advancement of personal computing equipment, the creation of image mosaic has entered the consumer market. Thus, automation of the process is an important issue. This paper proposes a new method for automatic generation of mosaics using Geometric Hashing. This speeds up the matching process. We show the application of our method on two important cases namely, rigid planar motion and panoramic mosaics. We provide experimental results in support of our proposed method.

Space efficient meta-grid lines for mutual coupling reduction in two-port planar monopole and DRA array

Traditionally used mutual coupling (MC) reduction techniques such as electromagnetic bandgap structures, isolators and neutralization lines require extra space between radiators. Besides, metamaterial-based techniques require multi-layer arrangements. However, the proposed meta-grid lines overcomes the above demerits by integrating meta-grid lines in the ground plane itself. As a proof-of-concept, two-port CPW-fed monopole antenna array (TPCFMAA) and two-port DRA array (TPDRAA) are designed, fabricated and tested. It has been observed that the TPCFMAA has mutual coupling below -20 dB for frequency between 2.6 to 4.4 GHz. The envelope correlation coefficient reduces from 0.072 to 0.026 by integrating meta-grid lines in the ground plane of the TPCFMAA. At 3.5 GHz, the inter-element distance between the antennas is noted to be 0.015λh (λh= highest operating wavelength). The TPDRAA's operating frequency can be tuned by changing the parameters of the annular ring slot in the excitation patch. The bandwidth of TPDRAA can be further increased by merging the two resonances of the two annular ring slots in the excitation patch. For TPDRAA, the measured -10 dB impedance bandwidth is from 5.65 to 6.55 GHz. The mutual coupling between the antenna elements is seen to be below -16 dB for an inter-element spacing of 4.8 mm, which is 0.090λh. The measured gain of TPDRAA within the bandwidth is from 4.17 dBi to 5.2 dBi. The TPCFMAA can be used in 3.5 GHz Internet of Vehicles (IoV) multi-user MIMO service, whereas the TPDRAA can be used for satellite communication in the 5.925 to 6.425 GHz frequency band, WiMAX in the 5.7 to 5.85 GHz band, ISM in the 5.725 to 5.85 GHz band, and WLAN in the 5.8 GHz band.Published versionThis work was supported by the Indian Institute of Technology Guwahati, Guwahati, India

A Highly Efficient Low-Mutual Coupling Partial π/8 SIW Cavity Based 8-Port MIMO Antenna

 A sector-shaped compact π/8 partial substrate-integrated waveguide cavity antenna from the TM220 diagonal mode of the SIW cavity is presented. A 61% size miniaturization is achieved compared to the SIW rectangular cavity in its complete mode configuration. The compact cavity radiator is used as an element of a compact 8-port multiple-input multiple-output (MIMO) antenna. The 8-port MIMO antenna occupies the entire full cavity with slots loaded on the top and bottom layers. The fabricated prototype has a -10 dB impedance bandwidth (BW) from 6.006-6.143 GHz. The mutual coupling within the BW is less than -21 dB. The presented MIMO antenna has an envelope correlation coefficient (ECC) less than 0.0027, and a percentage diversity gain reduction below 1.73%, which makes it a suitable candidate for use in MIMO-based wireless communications (This paper has been accepted for publication in  IEEE Antennas and Wireless Propagation Letters )</p