Feeding structure influence on performance of two UWB antennas near a human arm

This paper reports a study of the feeding structure influence on impedance matching and system fidelity factor of two loaded UWB antennas when placed near a human arm. To this aim, two identical dielectric loaded versions of the same UWB antenna designs with different feeding structures, CPW- and microstrip (MS)-fed, were studied and placed 3 mm away from a human arm to have the maximum expected effects of the body. Results of the considered antennas show that, in body proximity scenarios, the CPW-fed antenna detunes ~39% less than the MS-fed. Moreover, the feeding structure has minimal effect on pulse distortion with a 2% and 0.4% average system fidelity factor deviation from CPW- to MS-fed in free space and in arm proximity, respectively. Furthermore, the system fidelity factor near the arm and free-space is almost unchanged with an average deviation of 1.5% and 0.2% for CPW- and MS-fed antennas, respectively.