Phase Noise Induced by a Vibrating Antenna

When an antenna vibrates, it induces phase noise on the signals that it transmits and receives. This noise source is significant for microwave and millimeter-wave systems operating in high-vibration environments that require low phase noise at small frequency offsets. The purpose of this paper is to derive equations to compute phase noise from vibration parameters and to validate the equations with measurements. It is shown that the induced phase noise varies as f
_v
^-4
, where f
_v
is the frequency of vibration. The results are then compared to the phase noise induced on an oscillator by vibration to determine the oscillator g sensitivity such that the oscillator and antenna phase noise contributions are equal. For state-of-the-art low-g-sensitivity oscillators, the phase noise contribution of the antenna can dominate at vibrational frequencies up to several kilohertz. The vibrational phase noise sensitivity of the antenna is also larger than the reported vibrational sensitivity of coaxial cables up to at least 1000-Hz vibrational frequencies and bandpass filters up to 300-1000-Hz vibrational frequencies depending on the filter quality factor.