Problems Encountered in High-Frequency Surface-Wave Devices.

摘要

Propagation loss and pattern resolution are well recognized as serious impediments to the realization of practical surface-wave devices at frequencies greater than 1 GHz. In addition, a number of lesser-known problems become critical. Both propagation loss and dispersion are strongly affected by the character of the substrate surface. Damage layers on LiNbO3 with a thickness of only a few tens of angstroms cause velocity dispersion of the order of 0.001 at 1 GHz. This dispersion introduces troublesome phase errors in surface-wave devices. Phase errors also result from the limited accuracy of electron-beam and interferometer-controlled pattern generators. Dynamic range is restricted by the occurrence of acoustic non-linearities at relatively modest input powers. The magnitude of these effects can be estimated and, in many cases, special techniques are available for alleviating these problems and achieving successful high-frequency devices. (Author)