  Noise parameters are a set of four measurable quantities which determine the
noise performance of a radio-frequency device under test. The noise parameters
of a 2-port device can be extracted by connecting a set of 4 or more source
impedances at the device's input, measuring the noise power of the device with
each source connected, and then solving a matrix equation. However, sources
with high reflection coefficients cannot be used due to a singularity that
arises in entries of the matrix. Here, we detail a new method of noise
parameter extraction using a singularity-free matrix that is compatible with
high-reflection sources. We show that open, short, load and an open cable
("OSLC") can be used to extract noise parameters, and we detail a practical
measurement approach. The OSLC approach is particularly well-suited for
low-noise amplifier measurement at frequencies below 1 GHz, where alternative
methods require physically large apparatus.
