An Active Microstrip Leaky-Wave Antenna Employing Uniplanar Oscillator

In this paper we describe the design and construction of uniplanar GaAs HEMT oscillator which couples the electromagnetic energy to the microstrip leaky-wave antenna on the same substrate. The microstrip line was excited by a slotline on the opposite side of the substrate to obtain the desired first higher-order odd mode excitation. Thereby, the directional RF beam can be combined quasi-optically through the active antenna array. The active antennas were built in the form of uniplanar MICs (microwave integrated circuit), where no via holes and no DC blocking capacitance are required. The prototype active antenna was designed and tested at X-band, but it can be extended to higher frequency for quasi-optical application.