A CPW-to-slotline active Gunn diode leaky wave antenna

A X-band coplanar waveguide (CPW) to slotline couple feeding active microstrip leaky wave antenna using Gunn-diode oscillator as source is demonstrated. The method to excite the first higher order mode of the microstrip leaky wave antenna is to put the CPW-to-slotline transition underneath the middle of the microstrip line, and the oscillator circuit and radiating element are separated by a ground plane. The measured angle of the maximum beam direction of active antenna is at 72/spl deg/ for the active Gunn oscillator frequency of 11.218 GHz. This prototype of active leaky wave antenna feeding by Gunn diode oscillator with CPW-to-slotline structure can be easily scaled up to millimeter wave frequency region.