In the last decade the application of beam steering antennas and arrays to microwave and millimeter wave imaging for breast cancer detection, contactless security check and brain stroke monitoring has become important. Some of the reasons for this are due to its non-ionizing radiation nature, low cost and potential for fast reconstruction imaging.

Phased-array antennas, which offer beam scanning capabilities by tuning the phases of individual radiating elements, are most commonly used in these applications. Mechanical scanning is unsuitable for high-speed scanning applications and therefore electronic scanning, based on tunable phase shifters, is currently the most suitable approach. However the tunable phase shifters utilized are limited by the continuity of the phase shift and thei...[ Read more ]

In the last decade the application of beam steering antennas and arrays to microwave and millimeter wave imaging for breast cancer detection, contactless security check and brain stroke monitoring has become important. Some of the reasons for this are due to its non-ionizing radiation nature, low cost and potential for fast reconstruction imaging.

Phased-array antennas, which offer beam scanning capabilities by tuning the phases of individual radiating elements, are most commonly used in these applications. Mechanical scanning is unsuitable for high-speed scanning applications and therefore electronic scanning, based on tunable phase shifters, is currently the most suitable approach. However the tunable phase shifters utilized are limited by the continuity of the phase shift and their cost. In contrast, frequency beam steering offers a more economical and convenient solution for a number of applications, such as imaging, spectrum analysis and radar.

In the first contribution, beam steering rate is defined and enhanced technology based on a dispersive element is proposed. The dispersive element is used to engineer the slope of the dispersion curve of the unit cell in periodic leaky wave antennas. Though having a flat response in its dispersion curve, the beam steering rate is enhanced.

In the second contribution, glide symmetry is utilized to suppress the open-stopband in leaky wave antennas. The gilde symmetry structure has a closed open-stopband at ę = ęÐ in its dispersion curve. When loading the slow wave glide symmetry transmission line periodically, the closed point could be shifted to ę = 0 in its dispersion curve, and this corresponds to the broadside direction.

In the third contribution a dispersive feeding network is proposed to realize an arbitrary frequency beam steering array antenna. Through engineering the frequency dependent phase difference by a dispersive network, the desired steering relation can be achieved.