A design theory on broadband patch antennas with slot

Design assumes a set of required properties and then finds a physical structure as the design solution. The solution is nonlinear and frequently non-unique, and is therefore time consuming procedures have to be used. The time required may be greatly reduced, if a theory can be found to arrive at the design rules and, thus, an initial solution which is close to the final solution before the adjustment iterations begin. With the possibility of final iterations, the design theory needs not be very accurate. The theory, however, has to be simple and clear so that the effective parameters for adjustments can readily be identified. The set of such parameters are small to ensure rapid iteration. Since the solution is non-unique, a small number of parameters are usually sufficient to reach the desired solution within the usual engineering tolerance. Since high accuracy is not needed, the theory can be based on small matrices and simple mathematics, and then be synthesized from experiments and/or detailed numerical analyses plus, of course, physical insight. It is known that an antenna patch with a U-slot is broadband, unlike the ones without slots. The design rules and theory, however, have not been clear. This paper clarifies these based on the principle stated above. With the design rules and mechanism understood, other shape patches and slots such as a W-slot can be synthesized and give similarly good results.