Optimum source admittance matching for low-noise receivers without transformer

The noise behaviour for various connections of two 2-ports has been theoretically considered previously. A generalisation of the results yields an equation for the noise factor of n parallel 2-ports. It follows from this equation that the optimum source admittance for low-noise receivers can be matched without a transformer, a fact which may be very useful in the v.h.f. and u.h.f. ranges, where lossless impedance transformation is difficult.