How do I use CST Microwave Studio for simulating the radiation pattern of a patch antenna?

Using CST Microwave Studio for simulating the radiation pattern of a patch antenna involves creating the antenna geometry, defining the excitation, setting up the simulation boundaries, running the solver, and post-processing the results to obtain the antenna's radiation pattern, gain, directivity, beamwidth, and input impedance. The simulation setup is: create the antenna geometry (model the patch element as a rectangular or circular conductor on one side of the dielectric substrate, with a ground plane on the opposite side; include the feed structure: microstrip feed line, coaxial probe feed, or aperture-coupled feed; dimension the patch: for a resonant rectangular patch at frequency f: patch length L approximately lambda_d/2 = c/(2f x sqrt(Er_eff)), patch width W approximately 1.2L for good radiation efficiency), set the substrate properties (define the dielectric material with Er and loss tangent at the simulation frequency; common substrates: Rogers RT/duroid 5880 (Er=2.2), Rogers RO4003C (Er=3.55), FR-4 (Er=4.3)), define the excitation (for a microstrip-fed patch: use a waveguide port at the edge of the microstrip line; for a coaxial-probe-fed patch: use a discrete port or waveguide port at the coaxial feed point), set the simulation boundaries (use open (perfectly absorbing) boundary conditions on all sides of the simulation volume to model the radiation into free space; the boundary must be at least lambda/4 from the antenna edges to minimize boundary reflections; CST's open boundary automatically applies the Perfectly Matched Layer (PML) absorber), run the time-domain solver (CST's transient solver is the standard choice for antenna simulation; it excites the antenna with a broadband pulse and computes the time-domain response, then Fourier-transforms to obtain S11 and the radiation pattern across the entire frequency band in a single run), and post-process (view S11 to determine the resonance frequency and impedance bandwidth, the 3D radiation pattern (gain versus theta and phi), the 2D patterns (E-plane and H-plane cuts), the directivity, the radiation efficiency, and the surface current distribution on the patch).