  Theoretical and experimental results for in-plane vibrations of a uniform
rectangular plate with free boundary conditions are obtained. The experimental
setup uses electromagnetic-acoustic transducers and a vector network analyzer.
The theoretical calculations were obtained using the plane wave expansion
method applied to the in-plane thin plate vibration theory. The agreement
between theory and experiment is excellent for the lower 95 modes covering a
very wide frequency range from DC to 20 kHz. Some measured normal-mode wave
amplitudes were compared with the theoretical predictions; very good agreement
was observed. The excellent agreement of the classical theory of in-plane
vibrations confirms its reliability up to very high frequencies.
