| 21. | In 1938, George Brown et al . patented a loop antenna with rhombic shape and quarterwave sides.
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| 22. | Furthermore, the loop antenna was somewhat directional.
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| 23. | The " sense coil ", another loop antenna, is placed in the area between the field coils.
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| 24. | Simple half-wave dipole antenna for VHF or UHF loop antennas that are made to be placed receiver.
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| 25. | Loop antennas are often used for reception.
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| 26. | Loop antennas are relatively easy to build.
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| 27. | This provides a considerable advantage for loop antennas which are relatively insensitive to the main interference sources encountered.
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| 28. | For reception, long wire antennas are used, or more often ferrite loop antennas because of their small size.
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| 29. | It can be as well a dipole antenna, a loop antenna, a parabolic antenna, or an antenna array.
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| 30. | WiTricity is based on weakly coupled electromagnetic resonant objects to magnetic loop antennas critically tuned to the same frequency.
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