Transmission line equivalent circuits for 2-D active grid antenna arrays

Two-dimensional active grid arrays are being investigated for the submillimeter frequency range. The quasioptical Josephson oscillator is a large 2-D array of active antennas. Each active antenna consists of an active device integrated with a short antenna. For the active device, the Josephson function is used. Because of the extremely small power output of the single oscillator ( approximately nW), a large array of active antennas needs to be employed. The power radiated from each active antenna is quasioptically combined using the Fabry-Perot type cavity to give useful power levels. The arrays are designed for baseband operation, i.e. for the broad frequency range below the first array resonance. Several grid arrays have been measured and characterized. Of the four arrays considered, the slot array has the smallest input impedance and the dipole array has the highest. The bow-tie array represents the best combination of the wide baseband operating range and moderate driving point impedance.<>