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By CST of America, Inc.

The design of a UWB dipole antenna with circular arms presented at ICU 2005 in Zurich has been modeled and simulated with CST MICROWAVE STUDIO (CST MWS). The dipole has been chosen for its omnidirectional radiation pattern -- a wide bandwidth is obtained by using circular arms. The special feeding removes any unwanted radiation pattern disturbances.

The dimensions of the dipole arms and strip-line feed, shown in Figure 1, were taken from the paper. Some dimensions concerning the exact transition from SMA to the stripline were not given so a rough estimate of these dimensions was made as depicted in Figure 2. It should be noted that the feeding and transition region is very critical with respect to the antenna's performance.

The antenna was parametrically modeled and embedded in an open air environment using open boundary conditions. For the calculations, perfectly conducting material is assumed for all metal parts and a lossy dielectric of FR4 applied with a tangentdelta = 0.025 at 5 GHz using a Debye characteristic. A magnetic half symmetry condition along the elevation plane was used. The inital mesh was created using the default settings. Through the implementation of the PERFECT BOUNDARY APPROXIMATION (PBA)® technique in CST MWS, the initial mesh could be kept very coarse without neglecting any small details.

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•Application Note: Ultra-Wideband Printed Circular Dipole Antenna