| 摘要 |
<p>APPARATUS FOR MEASURING MICROWAVE ELECTROMAGNETIC FIELDS A microwave signal is transmitted from a transmitting antenna through a transfer medium to an electrically modulated and mechanically spun microwave scatterer. The scatterer may include an electric field responsive antenna, such as a dipole, for measurement of the electric field, or a magnetic field responsive antenna, such as a loop, for measurement of the magnetic field. An impedance within the scatterer is electrically modulated at an audio frequency, and the scat terer is mechanically spun at an angular frequency substantially below that at which it is electrically modulated. The scatterer thereby re-radiates to a receiving antenna a signal at the microwave source frequency which is modulated at both the frequency of electrical modulation and the mechanical spinning frequency of the scatterer. Signals from the microwave source and from the receiving antenna are combined to yield an output signal having a magnitude which is a function of the magnitude of the field received by the scatterer and which is phase shifted proportional to the phase shift of the microwave signal from the transmitting antenna to the scatterer and thence to the receiving antenna. The output signal may be compared with a signal coherent with the frequency of rotation of the scatterer to determine the tilt angle of the electric or magnetic field received by the scatterer.</p> |
