| 摘要 |
<p>The level detector has a probe immersed into the container and supplied by h.f. generator with the required energy. An evaluation circuit responds to the amplitude of the h.f. signal at the probe (2). The latter is fitted with a surface wave resonator (8), extending towards the container inside. Pref. the resonator is in the form of a metal rod, whose length is a quarter of the wavelength of the energised, surface wave, or an odd multiple of the same. The metal rod may be coated with a dielectric layer (17). Alternately its surface is knurled. The probe may have a threaded member (11) for screwing into the wall (15) of the container. The member inner surface (16) supports centrally the surface wave resonator. The surface has a recess (18), retaining impedance matching circuits (9,10), coupled to the resonator via conductors (20,24).</p> |
