High-Sensitivity Broad-Frequency-Response Fiber-Optic Radio-Frequency (RF) Field Sensor

摘要

Mission Research Corporation has developed a minimally-perturbing, broadband, fiber-optic RF probe for AFRL, Rome. This probe operates from 100 MHz to 18 GHz as limited by an output low-noise amplifier. Without its output amplifier, its response is flat from below 1 MHz to 8 GHz, but drops considerably from 8 GHz to 18 GHz. The probe outputs an RF signal proportional to the RF field at the probe head. This frequency response along with dipole- like antenna patterns at 2, 8, and 15 GHz were measured at AFRL, Rome, NY. The output RF voltage is approximately 10 -4 meters times the field (below 8 GHz). The noise-equivalent RF field level is tenths of mV/m times the square root of the noise bandwidth of the read-out device (e.g., the resolution bandwidth of a read-out spectrum analyzer). Advantages of the probe include very low perturbation of the fields being measured, a single fiber to the probe head (separate input and output fibers are not needed), and control of sensitivity stability from the data-room end of the fiber.