We present a new measurement technique of quantifying noise temperature based on temperature and time. A single pole double throw (SPDT) ultra-fast switch combines signal from outputs of two synchronized electromechanical (EM) switches. The input ports of EM switches are terminated by one unknown noise source, one known cold noise source, and two known noise references at ambient temperature. The magnitude of the combined noise signal can be adjusted by the duty cycle of the transistor-transistor logic (TTL) pulse that controls the fast switch. The measurement approaches the balanced mode by regulating the TTL duty cycle in order to minimize the difference between the combined noise signal and the ambient noise reference. In comparison to conventional total-power radiometers, this new instrumentation is more efficient and potentially provides a wider dynamic range.
Conference on Precision Electromagnetic Measurements