Waveguide element
AssigneeRaute Oyj
InventorsPete Ristola, Jaakko Vilo, Jerzy Piotrowski
Life of this patent
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Abstract
The invention relates to a microwave waveguide element for matching a standard waveguide input port (31) to an enlarged waveguide output port (37). In the waveguide element, a plurality of intermediate waveguide segments (B-E) is cascaded in the propagation direction of the microwave energy to first split the waveguide element into two symmetrical waveguide branches (34,36:34′,36′) and then combine the branches at the output port (37). Thus, the width of the waveguide element is gradually enlarged and the input port is matched to the output port. The intermediate waveguide segments are preferably dimensioned such that respective characteristic impedances are approximately matched with each other for the fundamental mode.
Claims9
A waveguide element, wherein the waveguide element is in form of a rectangular pipe made of electrically conducting material, the waveguide element comprising
- an input port having a standard rectangular cross-section with the width of the input port being bA in direction of the electric field of the fundamental mode,
- an output port having an enlarged rectangular cross-section, the width of the output port being C*bA in direction of the electric field of the fundamental mode,
- a plurality of intermediate waveguide segments cascaded in the propagation direction of the microwave power and arranged to split the waveguide element into two symmetrical waveguide branches which are again combined at the output port, the waveguide branches terminating to symmetrical horn-shaped waveguide segments of width C*bA/2 which are arranged to open to the output port, and wherein the splitting waveguide segments comprise
- a first intermediate waveguide segment having width bB in direction of the electric field of the fundamental mode, wherein bB>bA,
- a second intermediate waveguide segment having width bC in direction of the electric field of the fundamental mode, wherein bC>bB,
- third and fourth intermediate waveguide segments located in parallel to each other with a spacing bG to form first segments of said parallel branches, the third and fourth intermediate waveguide segments each having width bD in direction of the electric field of the fundamental mode, wherein said 2*bD+bG>bC.
An apparatus for microwave heating of a planar product, said apparatus comprising
- i) a first waveguide element in form of a rectangular pipe made of electrically conducting material,
- the first waveguide element further comprising
- an input port having a standard rectangular cross-section with the width of the input port being bA in direction of the electric field of the fundamental mode,
- an output port having an enlarged rectangular cross-section, the
- width of the output port being C*bA in direction of the electric field of the fundamental mode,
- a plurality of intermediate waveguide segments cascaded in the propagation direction of the microwave power and arranged to split the waveguide element into two symmetrical waveguide branches which are again combined at the output port, the waveguide branches terminating to symmetrical horn-shaped waveguide segments of width C*bA/2 which are arranged to open to the output port, and wherein the splitting waveguide segments comprise
- a first intermediate waveguide segment having width bB in direction of the electric field of the fundamental mode, wherein bB>bA,
- a second intermediate waveguide segment having width bC in direction of the electric field of the fundamental mode, wherein bC>bB,
- third and fourth intermediate waveguide segments located in parallel to each other with a spacing bG to form first segments of said parallel branches, the third and fourth intermediate waveguide segments each having width bD in direction of the electric field of the fundamental mode, wherein said 2*bD+bG>bC,
- ii) a feeding waveguide having said standard rectangular cross-section and being connected to said input port of the first waveguide element, and
- iii) a heating cavity having said second rectangular cross-section and being connected to said output port of the first waveguide element.
Dependencies are inferred from the claim text.