A new method is described to find the dielectric parameters of non-magnetic and magnetic solids at microwave frequencies. The method is tested on five non-magnetic substances and six ferrites. The open circuit and short circuit method is also employed to compare the values with the present method. The agreement is found to be good. Advantages of this method are that it removes the ambiguity in the selection of phase factor ( beta ), accuracy is improved because of the improved accuracy in the thickness measurements due to the plunger and the curve fitting techniques. Short circuit measurements are sufficient even for magnetic substances.