| 摘要 |
<p>A waveguide structure composed of circular waveguide cavities resonant in the TEo11 mode is capable of realizing the most general bandpass filter characteristics with significant decreases in filter loss and gain slope. In addition to the commonly used Tchebychev and Butterworth functions, the structure can realize general transfer functions, including the elliptic function. In its simplest form, the structure is composed of four cylindrical cavities which form a building block for more complex filters. The first and second cavities and the third and fourth cavities each have their side walls in contact and their end walls in common planes. The third and fourth cavities are superposed to the first and second cavities with their adjacent end walls in a common plane, but the second and third cavities are offset so that they overlap at one-half diameters. The first and second cavities are coupled by means of a centrally located side wall slot, as are the third and fourth cavities. Coupling between the second and third cavities is by means of a radial slot in their adjacent end walls, and the first and fourth cavities are similarly coupled. However, to generate the most general class of coupled transfer functions, the sign of the coupling between the first and fourth cavities and between the second and third cavities must be different. This is accomplished by the offset of the second and third cavities.</p> |
