2.1 The Transmission Line Model

The rectangular patch antenna is very probably the most popular microstrip antenna design implemented by designers. Figure 2-1 shows the geometry of this antenna type. A rectangular metal patch of width W = a and length L = b is separated by a dielectric material from a groundplane by a distance h. The two ends of the antenna (located at 0 and b) can be viewed as radiating due to fringing fields along each edge of width W (= a). The two radiating edges are separated by a distance L (= b). The two edges along the sides of length L are often referred to as non-radiating edges.

Figure 2-1: Rectangular Microstrip Patch Geometry used to describe the transmission line model. The patch antenna is fed along the centerline of the antenna's dimension along (i.e. x = a/2). The feed point is located at ? which is chosen to match the antenna with a desired impedance. The radiation originates from the fringing electric field at either end of the antenna. These edges are called radiating edges, the other two sides (parallel to ? axis) are non-radiating edges.

Numerous full wave analysis methods have been devised for the rectangular microstrip antenna. ^{[1] [2] [3] [4]} Often these advanced methods require a considerable investment of time and effort to implement and are thus not convenient for CAD implementation.