A compact 80-GHz band (81-86 GHz) 90° coupler using capacitively center-loaded microstrip transmission lines is proposed. The coupler is implemented in a 0.15 μm GaAs pHEMT technology and has longitudinal and transverse arms of the same characteristic impedances of 50-Ω to reduce the effect of manufacturing tolerance and to facilitate the layout. The experimental results demonstrated a phase difference close to 87° and an amplitude imbalance of less than 1 dB over the entire frequency band of interest (81-86 GHz). The measured return loss is less than 11 dB and the isolation is better than 15 dB. The proposed coupler is well suited for low-cost, high performance, ultra high data rate transceivers for E-band wireless communication systems.

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Keywords 60 GHz band, 90-degree coupler, capacitive loading, CPW transmission lines
Conference Asia-Pacific Microwave Conference, APMC 2011
Haroun, I. (Ibrahim), & Plett, C. (2011). Capacitively center-loaded transmission lines for compact E-band 90° couplers. Presented at the Asia-Pacific Microwave Conference, APMC 2011.