Bandwidth substitution technique for absolute measurement of power at all radio frequencies

A highly sensitive technique for making absolute measurements of power at all radio frequencies is described. This technique surmounts the primary shortcomings of the other existing techniques in that it permits absolute measurement of power at all radio frequencies, whereas all other techniques except one, the Incremental Method, are inherently frequency limited, with the current upper limit being about 75 GHz. This major advantage stems from the fact that this technique uses a direct comparison of the unknown RF power with a primary standard, whereas the other techniques (except for the Incremental Method) require a conversion of the power to heat before the comparison can be made. The main advantage of this technique over the Incremental Method is that it has much higher sensitivity, permitting absolute measurement of RF power to be made down to about -100 dBm, compared with only about -10 dBm for the Incremental Method. An additional advantage of this technique is that it permits the measurement of noise as well as coherent RF power, whereas the Incremental Method is valid only for coherent RF.