Antenna with electro-optical modulator
First Claim
1. A wideband, passive detector of electromagnetic fields comprising:
- an electro-optic modulator having first and second surfaces with electrodes attached thereto and third and fourth surfaces intersecting an optical path;
an antenna means having a first electrode connected to said first electrode of said modulator and a second electrode connected to said second electrode of said modulator for converting electromagnetic fields intercepted to a voltage signal to be applied to said first and second electrodes of said modulator;
a light source located above said optical path, for transmitting light into said modulator through said third surface;
said modulator modulating the light entering through said third surface, as it traverses said modulator, with said voltage signal impressed upon said first and second surfaces by said antenna means; and
a detector means located along said optical path for detecting said modulated light along said optical path as it exits from said modulator through said fourth surface whereby weak electromagnetic fields may be detected in free space with a negligible perturbation.
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Abstract
A wideband, passive detector of electromagnetic fields in free space is disclosed. The apparatus is especially designed to minimize amplitude perturbations of the electromagnetic field being monitored. The apparatus includes an electro-optic modulator having first and second surfaces with electrodes attached thereto and a third and fourth surfaces intersecting an optical path. An electrically small dipole or loop antenna has a first electrode connected to the first electrode of the modulator and a second electrode connected to the second electrode of the modulator, for converting electromagnetic fields intercepted in free space to a voltage signal to be applied to the first and second electrodes of the modulator. A loading resistor may be added in parallel with the electrodes to improve system bandwidth. A light source is located along the optical path, for transmitting light into the modulator through the third surface. The modulator modulates the light entering through the third surface, as it traverses the modulator, with the voltage signal impressed upon the first and second surfaces by the antenna means. An optical detector is located along the optical path for detecting the modulated light along the optical path as it exits from the modulator through the fourth surface. In this manner, weak electromagnetic fields may be detected and their amplitude, phase and frequency measured with a minimal perturbation due to a lack of metallic wires attached to the antenna as in conventional field measurement systems.
44 Citations
17 Claims
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1. A wideband, passive detector of electromagnetic fields comprising:
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an electro-optic modulator having first and second surfaces with electrodes attached thereto and third and fourth surfaces intersecting an optical path; an antenna means having a first electrode connected to said first electrode of said modulator and a second electrode connected to said second electrode of said modulator for converting electromagnetic fields intercepted to a voltage signal to be applied to said first and second electrodes of said modulator; a light source located above said optical path, for transmitting light into said modulator through said third surface; said modulator modulating the light entering through said third surface, as it traverses said modulator, with said voltage signal impressed upon said first and second surfaces by said antenna means; and a detector means located along said optical path for detecting said modulated light along said optical path as it exits from said modulator through said fourth surface whereby weak electromagnetic fields may be detected in free space with a negligible perturbation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification