{"references": ["SA Arunmozhi, SD Sairam (2014), \"A novel dual-band E and T-shaped planar inverted antenna for WLAN applications\", International Conference on Communication and Signal Processing, pp. 1922\u22121926.", "SA Arunmozhi, SC Krishnan (2014), \"Design\", International Conference on Communication and Signal Processing, pp. 1942\u22121946.", "Azari (2011), \"A new super wideband fractal microstrip antenna\", IEEE Trans. Antennas Propag., Volume 59, Issue 5, pp. 1724\u22121727.", "J Bai, S Shi, DW Prather (2011), \"Modified compact antipodal Vivaldi antenna for 4\u201350-GHz UWB application\", IEEE Trans. Microw. Theory Techn., Volume 59, Issue 4, pp. 1051\u22121057.", "Constantine A Balanis (2016), \"Antenna Theory Analysis and Design, Fourth Edition\", John Wiley and Sons,", "M Manohar, RS Kshetrimayum, AK Gogoi (2014), \"Printed monopole antenna with tapered feed line, feed region and patch for super wideband applications\", IET Microw., Antennas Propag., Volume 8, Issue 1, pp. 39\u221245.", "M Moosazadeh, S Kharkovsky, JT Case, B Samali (2016), \"Antipodal Vivaldi antenna with improved radiation characteristics for civil engineering applications\", IET Microw., Antennas Propag., Volume 11, Issue 6, pp. 796\u2212803.", "SM Nair, VA Shameena, R Dinesh, P Mohanan (2011), \"Compact semicircular directive dipole antenna for UWB applications\", Electron. Lett., Volume 47, Issue 23, pp. 1260\u22121262.", "GK Pandey, H Verma, MK Meshram (2015), \"Compact antipodal Vivaldi antenna for UWB applications\", Electron. Lett., Volume 51, Issue 4, pp. 308\u2212310.", "JY Siddiqui, YMM Antar, AP Freundorfer, EC Smith, GA Morin, T Thayaparan (2011), \"Design of an ultrawideband antipodal tapered slot antenna using elliptical strip conductors\", IEEE Antennas Wireless Propag. Lett., Volume 10, pp. 251\u2212254."]}

A compact, wideband, windmill shape ultra-wideband antenna is designed for mobile communication and a comparison is carried out among different substrate materials to investigate the most suitable substrate for the proposed antenna. UWB antennas are suitable for mobile communication due to its large bandwidth. The proposed antenna occupies a compact size of 34 mm x 30 mm. The design of the proposed antenna and the simulations are carried out in HFSS (High Frequency Structural Simulator). The antenna is designed on a polyethylene substrate with a dielectric constant (εr) of 2.25 and a thickness of 1.6 mm. This provides high return loss and gain when compared with other analyzed substrates. The antenna operates at a frequency band of 4 GHz to 10 GHz which is the recommended frequency range of UWB band by FCC. The maximum gain of the proposed antenna is 5.16 dB at 6 GHz and the directivity of the antenna is 5.27 dB with efficiency of 97.8 %. This antenna is suitable for UWB communication, with its broadband characteristics it can be utilized short-range communication.