Waveguide mode converter and method using same
First Claim
1. Waveguide mode converting apparatus for converting a first mode of transmission of electromagnetic power at a given free space wavelength to a second mode of transmission at the same wavelength, said apparatus including a length of circular corrugated waveguide of predetermined inner diameter and annular corrugations formed in a multiperiod periodic planar curve with a period substantially equal to 2π
- divided by the difference in axial wavenumbers of the respective first and second modes of transmission in said waveguide.
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Abstract
A waveguide mode converter converts electromagnetic power being transmitted in a TE0n or a TM0n mode, where n is an integer, to an HE11 mode. The conversion process occurs in a single stage without requiring the power to pass through any intermediate modes. The converter comprises a length of circular corrugated waveguide formed in a multiperiod periodic curve. The period of the curve is selected to couple the desired modes and decouple undesired modes. The corrugation depth is selected to control the phase propagation constant, or wavenumbers, of the input and output modes, thereby preventing coherent coupling to competing modes. In one embodiment, both the period and amplitude of the curve may be selectively adjusted, thereby allowing the converter to be tuned to maximize the conversion efficiency.
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Citations
21 Claims
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1. Waveguide mode converting apparatus for converting a first mode of transmission of electromagnetic power at a given free space wavelength to a second mode of transmission at the same wavelength, said apparatus including a length of circular corrugated waveguide of predetermined inner diameter and annular corrugations formed in a multiperiod periodic planar curve with a period substantially equal to 2π
- divided by the difference in axial wavenumbers of the respective first and second modes of transmission in said waveguide.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A tunable waveguide mode converter comprising:
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a length of circular corrugated waveguide formed into a multiperiod periodic planar curve, the periods of said multiperiod curve having a period P measured along a longitudinal axis of the waveguide, and said periodic planar curve having an amplitude A measured transverse to the longitudinal axis; first adjustment means for selectively adjusting said period P; and means for coupling electromagnetic power having a free space wavelength λ
in a first transmission mode to a first end of said length of circular waveguide;said period P being adjusted with said first adjustment means to couple power of said first transmission mode to a second transmission mode and decouple power of said first transmission mode to modes other than said second transmission mode. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for converting electromagnetic power at a given free space wavelength from a TE01 or TM02 input mode, to an HE11 output mode, said method comprising applying said power in said input mode to the input end of a length of circular corrugated waveguide of given inner diameter and annular corrugations formed in a multiperiod periodic planar curve, adjusting the period of said curve to maximize power radiating from the output end of said length of waveguide in said HE11 output mode, and adjusting the amplitude of said curve to minimize the power radiating from the output end of said length of waveguide in said input mode, thereby achieving maximum conversion to the HE11 mode.
Specification