Dot and stripe arrays as surface acoustic wave reflectors

Reflective dot arrays represent a promising innovation in the field of surface acoustic wave devices. This work has investigated a simple model for uniform rectangular dot arrays. Prom this model the reflection coefficents of the dots and the correct angle for the array's reflectors can be deduced. Experimental results for these parameters are reported for some specific types of metal dot array using aluminium dots on Y-cut lithium niobate. Several different arrangements of dots within the arrays have been investigated, and their different advantages and disadvantages are contrasted. The use of specific array patterns to suppress undesired reflection modes has been investigated, and it has been shown that such suppresion can be achieved by this means. Some information has been gathered on the reflection properties of different shapes of metal dots and with different thicknesses of metal. The properties of these different dot types have been compared and their implications on a theory for the behaviour of reflective metal dots have been discussed. Experimental results have been obtained for the reflection of surface waves on YZ lithium niobate by thin metal strips at normal incidence. These results have been shown to agree with the available theoretical models for the problem. The effect of the mutual capacity of the strips on their behaviour has been shown to be important if several of them are grouped together. This part of the work is seen as a preliminary to the possible development of a model for the reflection properties of metal dots. Two inline reflective dot array devices have been made. The results reported show that the principle of these devices has been sucessful, but that more work is still needed if they are to fulfil their full promise.