A Periodic CPW Leaky-Wave Antenna With Enhanced Gain and Broadside Radiation

In this letter, a periodic coplanar waveguide leaky-wave antenna with enhanced gain and continuous backward-to-forward beam scanning is presented. The leaky-wave antenna is made of coplanar waveguide with two symmetric transversal slots on the ground plane. The gain of the antenna is enhanced because of the radiation of the two slots superimposing in the H-plane. The relationship between Bloch impedance and characteristic impedance of the host coplanar waveguide is then investigated. By introducing a pair of matching slots, an improved impedance matching approach is presented to remove the dramatic variation of Bloch impedance at broadside frequency. Hence, the open-stop band (OSB) can be effectively suppressed and broadside radiation is achieved. Finally, a design prototype is implemented and fabricated as an experimental verification. The simulated and measured results show a good agreement. Both the reflection coefficient and radiation patterns verify that the open-stop band of the antenna is eliminated, while the gain is enhanced.