Ghassan Yassin

Abstract:

We present preliminary measured responses of a planar superconducting on/off switch centred at the 220 GHz. The superconducting switch, comprising three niobium nitride (NbN) bridges, deposited across the slotline section of a backto-back unilateral finline, made of a similar superconducting material. The transmission characteristics of the superconducting switch illuminated by a sub-millimetre source were measured using a superconductor-insulator-superconductor (SIS) chip as direct detector. The NbN bridges were switched from the superconducting state to the normal state by a bias current exceeding the critical current of the bridges. With this arrangement, we have measured a switching dynamic range of ∼ 13 dB at 245 GHz, demonstrating the successful operation of the multiple NbN bridges planar superconducting on/off switch.

Abstract:

We describe near-field tests and results of an 8 pixel close-packed feedhorn array that will be a key component of an 8 pixel prototype 350 GHz SIS mixer array receiver prototype under construction at SAO. We have fabricated an array of smooth walled multiple flare angle feedhorns by direct drilling into a single block of aluminum. Testing of the feedhorns was carried out using a nearfield scanner and a vector network analyzer based on custom built transmitters and receivers and an HP vector voltmeter. The vector nearfield data is transformed to the farfield radiation pattern using Python code based on the NF2FF Matlab script[1].