I copied the following diagram from a 1917 booklet called
Practical and Economical Methods of Keeping Vegetables, Fruits, and Meats.
It points out that even if your resources are limited, you can still dehydrate foods for next to nothing in the sun. Use several layers of cheesecloth stretched between frames pounded into the ground (or put on a stand of some sort, however you can manage it).
The spikes might be nails pounded into the underside of a narrow board to hold the cheesecloth in place.
Of course, this works best in a sunny, arid climate.
Linda's Note: My recommendation would be to drape an additional layer of cheesecloth across the top bars of your racks so that they hang down below the cloth supporting the food. This should help prevent flying insects from landing on it.