摘要 |
A method for measuring an absorption characteristic of a sample comprises: providing a microstrip waveguide comprising a ground plane, an elongate conductive strip having a first end and a second end, and a dielectric substrate separating the ground plane from the elongate strip such that the strip extends from its first end to its second end in a plane substantially parallel to the ground plane; emitting electromagnetic radiation from a first intermediate position along the microstrip waveguide, said first intermediate position being a position between the first and second ends of the strip, such that said radiation propagates along the waveguide in a direction towards the second end; positioning a sample at a position external to the microstrip waveguide and between the first intermediate position and a second intermediate position along the microstrip waveguide, the second intermediate position being a position between the first intermediate position and the second end, such that at least a portion of the sample is exposed to the evanescent electric field of the propagating radiation; and detecting at least one characteristic of the propagating radiation at said second intermediate position. Corresponding apparatus is also disclosed.
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