Is a radio frequency or microwave dryer better for drying large quantities of medicinal herbs?

I need to dry large quantities of different medicinal herbs used in native medicine. At present, they are dried under the sun over several days. I want to reduce moisture in fresh leaves, which have moisture content levels of 60 to 75%, to about 2 to 3%. Hot air drying at temperatures exceeding about 220°F (104°C) is ruled out. The dryer capacity required is on the order of 500 to about 1,500 lb/hr.

It has been suggested that either a radio frequency or microwave dryer might fit the bill. What do you suggest? - C.J.

Foods, medicines and other products intended for human consumption can be dried, cooked and processed by conveying them through a microwave oven on a conveyor belt coated with a fluoropolymer (Teflon). The conveyor belt will not heat up - only the product being conveyed will heat due to the microwave energy. The fluoropolymer coating will prevent contamination and also will keep the dried product from sticking. - Ed Kennedy, Taconic Inc., (800) 833-1805, ext. 307 or e-mail