Install an over-the-range microwave oven.... Most OTR microwaves are just under 30 in. wide; heights vary from about 10 to 18 inches and depths vary from 12 to about 18 inches. You need to choose a model that allows adequate clearance above the range but can be installed at a comfortable height.
How to Make Your Microwave Blend Seamlessly into Your Kitchen
Create new space in your kitchen. Free up counter space by swapping your countertop microwave for an over-the-range model. Then turn a slice of cabinet space above the microwave into an attractive display shelf.