Short-slot Hybrid Coupler Using Linear Taper in W-band

Abstract

-We have designed and fabricated a broadband short-slot hybrid coupler using a twostage linear taper in W-band. The coupler consists of two metal pieces split at the edge of the narrow wall of the waveguide, which makes it possible to use simple direct machining for fabrication. The electrical performance of the coupler was measured by a Vector Network Analyzer (VNA) at room temperature. The results showed excellent performance as designed: amplitude imbalance between the two output ports of ≤ 1 dB, phase difference between the output ports with respect to 90°< 3°, input return loss < -15 dB, and isolation < -15 dB across the measured frequency range of 85-110 GHz. The short-slot hybrid coupler was used in a balanced Superconductor-Insulator-Superconductor (SIS) mixer at 4 K. The noise performance was almost the same as that of the two single-ended mixers used in the balanced mixer. These results indicate that our short-slot hybrid coupler has great potential for practical applications, such as at millimeter-and submillimeter-waves.

Design of Terahertz Short-Slot Coupler With Curved Waveguide

“…This is caused by the fabrication error of 5 µm. coupler working frequency coupling coefficient coupling variation isolation Fang et al [5] 80 ∼ 100 GHz 3 dB < 1 dB > 7 dB Kuroiwa et al [6] 80 ∼ 120 GHz 3 dB < 2 dB > 10 dB Castellano et al [7] 10 ∼ 13 GHz 3 dB < 2 dB > 10 dB Liu et al [8] 325 ∼ 400 GHz 10 dB < 2 dB > 10 dB proposed coupler 340 ∼ 400 GHz 3 dB < 1 dB > 10 dB…”

“…It has achieved a coupling variation of less than 1 dB, and the isolation is greater than 7 dB. In 2013, Kuroiwa et al [6] proposed a short-slot hybrid coupler in W band using linear taper. The measured results show that the coupling variation is less than 2 dB and the isolation greater than 10 dB.…”