Applications of the Open-Stopband Suppression in Various Periodic Leaky-Wave Antennas With Tapered Half-Wavelength Line

This paper presents applications for the suppression of the open stopband (OSB) in various periodic leaky-wave antennas (P-LWAs) using a tapered half-wavelength line. With the adoption of a slightly tapered half-wavelength line for each unit cell, the OSB can be completely suppressed. The technique is very convenient for engineering application, without the calculation of the characteristic impedance of the line. It can be applied to various structures, including planar and nonplanar structures. The design rule is generalized. Three examples are illuminated to demonstrate the applications. The first example is a series-fed microstrip patch antenna. The second one is a coaxial cable leaky-wave antenna. The third demonstrated antenna is a new substrate integrated waveguide (SIW) P-LWA with trapezium slots. The SIW antenna owns the advantages of wide-angle scanning and high efficiency. A prototype of the SIW antenna is fabricated and measured, to validate the effectiveness of the technique.