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Jagadis Chandra Bose

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ANTENTOP- 02- 2003, # 003

Jagadis Chandra Bose

 

Oscillation is produced by sparking between 2 hollow hemispheres and the interposed sphere. There is a bead of platinum on the inside surface of each hemisphere. For some experiments, a lens of glass or of sulphur was used to collimate the radiation - the first waveguide-lens antenna. The lens was designed according to the refractive index measured by Bose at the wavelength in use. Figure 3(b) shows Bose's drawing of such a radiator; the sparks occur between the two outer spheres to the inner sphere, at the focal point of the lens L at the right. Bose was able to measure the wavelength of his radiation with a reflecting diffraction grating made of metal strips [7].

Figure 4(a) is a photograph of one of his radiating antennas; part of the spark oscillations are generated inside the overmoded circular waveguide. A polarizing grid is built into the antenna, clearly visible at the radiating end of the waveguide. Figure 4(b) shows a closeup of the dual spark gaps used for the transmitter; the sparks are generated between the 2 outer spheres and the inner sphere. Figure 4(c) shows both a transmitting antenna (left) and the receiver (right), with a dual prism in between set on the experimental rotating table.

Figure 3(b)

 

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Figure 3 Bose's diagrams of his radiators. (a) shows the radiator used to generated 5-mm radiation, while (b) shows the arrangement with a lens L at the exit of the waveguide [2]. In some designs the mounting stems for the outer spheres could be inclined to adjust the dimension of the spark gaps.

 

 

Figure 4(a)

One of Bose's transmitter antennas (being held on the right of the picture). Note the polarizing grid; the spark gap is just visible behind the grid. In the background behind this antenna part of the high voltage equipment used to generate the spark can be seen. At the left of the picture is a receiving horn.

 

Figure 4(b): A closeup of the spark gaps normally mounted inside the transmitting antenna

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