A compact local oscillator distribution network design for Leighton Chajnantor Telescope based on a center frequency of 115 GHz

Superconductor-insulator-superconductor (SIS) receivers are widely applied in millimeter/submillimeter astronomical observations. Developing multi-beam focal plane arrays (FPAs) is an effective approach for enhancing the observational efficiency. Herein, we designed and simulated a novel local oscillator (LO) distribution network for a 1 × 3 pixel array, a key component of multi-beam FPAs, with a central frequency of around 115 GHz. Compared to SIS arrays assembled using traditional methods, this design offers superior compactness and scalability. The simulation results demonstrate that the design achieves uniform LO signal distribution across all output ports within the 107–128 GHz frequency band. The relative amplitude difference is less than 0.8 dB, with return loss and isolation better than −20 dB, and isolation between output ports exceeding −15 dB. The compactness, wide bandwidth, and high isolation of the LO distribution network provide a foundation for upgrading Leighton Chajnantor Telescope's multi-beam system.