File:Southworth demonstrating waveguide.jpg
Summary
Demonstration in 1938 of the <a href="https://en.wikipedia.org/wiki/waveguide" class="extiw" title="w:waveguide">waveguide</a> before the Institute of Radio Engineers by the inventor, <a href="https://en.wikipedia.org/wiki/Bell_Telephone_Laboratory" class="extiw" title="w:Bell Telephone Laboratory">Bell Telephone Laboratory</a> scientist <a href="https://en.wikipedia.org/wiki/George_C._Southworth" class="extiw" title="w:George C. Southworth">George C. Southworth</a> (left). Behind the blackboard (right) were several vacuum tube oscillators producing 1.5 GHz (8 inch, 20 cm) <a href="https://en.wikipedia.org/wiki/microwaves" class="extiw" title="w:microwaves">microwaves</a> of different modes. He demonstrated that they could pass through the 25 ft flexible metal waveguide and be detected by a receiver consisting of a <a href="https://en.wikipedia.org/wiki/silicon_diode" class="extiw" title="w:silicon diode">silicon diode</a> coupled to an amplifier and galvanometer. He demonstrated further properties of the waves:
- Using a metal paddle reflector he created standing waves.
- Using an electric field probe he demonstrated the E field structure of the different modes.
- By using progressively smaller diameter pipe (seen at right on floor) he showed that waves would not propagate through a waveguide that was under a certain diameter, that is, each waveguide had a <a href="https://en.wikipedia.org/wiki/cutoff_frequency" class="extiw" title="w:cutoff frequency">cutoff frequency</a>.
- A brass grating in one orientation could block the waves but in perpendicular orientation allowed them through
- The propagation velocity was less than that of waves in open air.
- A soft rubber rod could also conduct the waves, forming a <a href="https://en.wikipedia.org/wiki/dielectric_waveguide" class="extiw" title="w:dielectric waveguide">dielectric waveguide</a>.
Caption: Dr. George C. Southworth and his assistant A. E. Bowen of Bell Telephone Labs show how extremely short electric waves can be guided through a flexible metal pipe
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 14:59, 13 January 2017 | | 810 × 620 (94 KB) | 127.0.0.1 (talk) | Demonstration in 1938 of the <a href="https://en.wikipedia.org/wiki/waveguide" class="extiw" title="w:waveguide">waveguide</a> before the Institute of Radio Engineers by the inventor, <a href="https://en.wikipedia.org/wiki/Bell_Telephone_Laboratory" class="extiw" title="w:Bell Telephone Laboratory">Bell Telephone Laboratory</a> scientist <a href="https://en.wikipedia.org/wiki/George_C._Southworth" class="extiw" title="w:George C. Southworth">George C. Southworth</a> <i>(left)</i>. Behind the blackboard <i>(right)</i> were several vacuum tube oscillators producing 1.5 GHz (8 inch, 20 cm) <a href="https://en.wikipedia.org/wiki/microwaves" class="extiw" title="w:microwaves">microwaves</a> of different modes. He demonstrated that they could pass through the 25 ft flexible metal waveguide and be detected by a receiver consisting of a <a href="https://en.wikipedia.org/wiki/silicon_diode" class="extiw" title="w:silicon diode">silicon diode</a> coupled to an amplifier and galvanometer. He demonstrated further properties of the waves: <ul> <li>Using a metal paddle reflector he created standing waves.</li> <li>Using an electric field probe he demonstrated the E field structure of the different modes.</li> <li>By using progressively smaller diameter pipe <i>(seen at right on floor)</i> he showed that waves would not propagate through a waveguide that was under a certain diameter, that is, each waveguide had a <a href="https://en.wikipedia.org/wiki/cutoff_frequency" class="extiw" title="w:cutoff frequency">cutoff frequency</a>. </li> <li>A brass grating in one orientation could block the waves but in perpendicular orientation allowed them through</li> <li>The propagation velocity was less than that of waves in open air.</li> <li>A soft rubber rod could also conduct the waves, forming a <a href="https://en.wikipedia.org/wiki/dielectric_waveguide" class="extiw" title="w:dielectric waveguide">dielectric waveguide</a>.<br> </li> </ul> Caption: <i>Dr. George C. Southworth and his assistant A. E. Bowen of Bell Telephone Labs show how extremely short electric waves can be guided through a flexible metal pipe</i> |
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