抄録
In order to construct a frequency filter for water waves, an equivalent electric circuit analogous to a rectangular channel, which is considered as the standard structure, is analyzed. Features of propagation of shallow water waves in the channel show just the same properties as TE or TM electromagnetic wave transmitting in a space limited by two parallel infinite conducting plates. Namely, the rectangular channel shows the characteristics of high-pass filter for shallow water waves fundamentally. In the wave transmission region, however, it has band-pass characteristics with frequency, although they depend on several parameters of the channel dimension and wave mode. Also in the case of deep water waves, the same features as in the above case, such as the essential high-pass and the band-pass characteristics in the transmission region, are obtained. More detailed properties, however, are somewhat or quite different between both cases.
By utilizing the property of the equivalent electric circuit, a desired wave filter can be provided by series or parallel combination of such channels. A lumped element constant K-type filter is designed, and the experimental result of frequency responce of the filter coincides with the theoretical calculation.
