Recently, Dr. YANG Qingshan and Prof. ZHANG Yunhua from the Key Laboratory of Microwave Remote Sensing, the Chinese Academy of Sciences, proposed a novel left-handed transmission line with the advantages of low cost, low profile, miniaturized size and flexible design, and applied it to the miniaturized filters and novel electronic scanning antennas.

Left-handed transmission lines have always been a research hotspot and been applied to materials, circuits and antennas in the past decade due to their unique characteristics such as negative phase velocity, negative refraction, etc.

Negative phase velocity means that the phase propagates towards the source rather than the load, while the negative refraction means that the incident and refracted directions locate at the same side of the normal. It is different from what we use to think that the incident and refracted directions locate at the different sides of the normal. Figure 2 shows the propagation process of cylindrical electromagnetic waves at the interface between air and left-handed medium, and between air and regular medium. Both figures illustrate the unique characteristics of the left-handed transmission line.

The concept of waveguide slot array can be applied to design the frequency scanning antenna with full space scanning ability. According to the research team at the National Space Science Center (NSSC), the newly developed left-handed transmission line will have a promising future in radar systems requiring wide range of beam-steering. 

The relevant researches entitled Composite Right/Left-Hand Ridge Substrate Integrated waveguide Slot Array Antennas and Nagative-order Ridge Substrate Integrated Waveguide Coupled-resonator Filter were published on IET Electronics Letters and IEEE Transactions on Antennas and Propagation.

Figure 1: Novel electronic scanning antenna based on the proposed left-handed transmission line