A Fixed-Beam Leaky Wave Antenna With Coupling Elements of Multiresonance

A novel technique is proposed for the fixed-beam design of leaky-wave antennas (LWAs) by periodically loading multi-resonance elements. The single-resonance elements can generate phase shift with negative slope in a narrow band for phase compensation, which are used to design an LWA with fixed-beam. Furthermore, the fixed-beam bandwidth can be expanded by loading a set of different resonant elements. A design of fixed-beam microstrip LWA using the multi-resonance technique is demonstrated and investigated. The antenna consists of a main microstrip line that is periodically loaded with a set of L-shaped coupling patches of different sizes on both sides. The patches have different resonant frequencies, which act as radiators to generate leaky-wave radiation and as resonant elements to compensate for dispersion in a wide operating band. A prototype of the antenna designed for radiating at -14° is fabricated and measured. Measurement results show that the antenna has only a 2.9° beam-squinting in the operating band from 14.2 to 15.7 GHz (with a fractional bandwidth of 10.1%), with a peak gain varying from 11.6 to 14.2 dBi. The bandwidth is almost 4 times that of the LWA with single-resonance elements loading.