The ability of XFdtd^® to generate arrays is used in this example of a three patch antenna array.

The geometry is taken from the paper “A New Design of Horizontally Polarized and Dual-Polarized Uniplanar Conical Beam Antennas for HIPERLAN” by Neil J. McEwan, Raed A. Abd-Alhameed, Embarak M. Ibrahim, Peter S. Excell, and John G. Gardiner published in the February 2003 issue of IEEE Transactions on Antennas and Propagation. The Geometry of the patch array is shown in Figure 1. The patch array is mounted on a 75 cm square metal finite ground plane covered with a 1.524 mm dielectric substrate with relative permittivity 2.55 and loss tangent 0.0024. The patches are designed to resonate at 5.0 GHz. Using the XFdtd parameters calculator the loss tangent is equivalent to a conductivity of 0.00170235 which is used to define the substrate material for this calculation.

To simplify the geometry generation, portions of the array aligned with the coordinate axes are entered and then rotated to generate the complete array. The process begins with the finite ground plane and substrate, then the vertical patch and vertical and horizontal feed lines are added. The result is shown in Figure 2. Each of these geometry elements is then used as the basis of an array using the menu shown in Figure 3. The result after generating the patch and one of the traces is shown in Figure 4. The final geometry after forming the entire patch array is shown in Figure 5. The final step before generating the mesh is to add a connecting wire between the ground plane and the center of the array feed at the feed point.

Once the geometry is generated we are ready to generate the mesh. XFdtd will suggest a cell size, but in this case we will choose a cell size of 0.19 mm since this will allow two cells across the feed lines and a more-than-sufficient 8 cells over the depth of the substrate. The resulting mesh of the patch array is shown in Figure 6.

Now that the mesh is generated we are ready to define the calculation parameters. First add a feed port at the base of the feed wire as shown in mesh view in Figure 7 to simulate a coaxial feed from the bottom of the ground plane. Then define the frequency as 5.0 GHz and save fields in several principal planes of interest. Some example field views are transient electric field in Figure 8, steady state electric field in Figure 9, and steady state conduction currents in Figure 10.

The paper provides measured radiation patterns for the three patch array. The results shown in Figures 11, 12, and 13 show good agreement with the measured patterns in the paper.