### ASA 124th Meeting New Orleans 1992 October

## 1pUW6. A comparison between ray theory and normal mode theory to very high
frequencies.

**E. White
**

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M. F. Werby
**

**
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*NRL, Theor. Acoust. Codes 223 and 221, Stennis Space Center, MS 39529
*

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A new normal mode method capable of predictions to very high frequencies
is developed. The objective is to compare predictions of ray theory with the
more exact normal mode theory to determine how well and at what point ray
theory agrees with normal mode theory. The approach is to compare transmission
loss curves computed by both methods. Discussion of the discrepancies are made
and comments will be made on how improvements can be implemented. In strong
ducting problems it is shown that there is a strong association between the
lower order modes and the ray trace results.