Directional Power Sensor 200MHz-4GHz, 30mW - 120 (300)W, R&S ID 1165.2305.02 The R&S FSH-Z44 is a Directional Power Sensor designed to be used with the R&S FSH handheld spectrum analyzer for simultaneous measurement of forward and reflected power. The R&S FSH-Z44 offers a frequency range from 200 MHz to 4 GHz and a measurement range from 30 mW to 300 W.