Wireless Pers Commun DOI 10.1007/s11277-014-2045-z Small Monopole Antenna for IEEE 802.11a and X-Bands Applications Using Modiﬁed CBP Structure Tohid Sedghi · Shahin Shafei · Arash Kalami · Tohid Aribi © Springer Science+Business Media New York 2014 Abstract In this paper, a novel microstrip-fed monopole antenna is constructed and tested to cover the following operational bands: WLAN (5,150–5,350/5,725–5,825 MHz speciﬁed by IEEE 802.11a) and X-band (8–12 GHz). In this antenna, the aim is to propose a simple conﬁguration of patch and ground plane with a step-by-step process design of conductor back plane to access dual-band speciﬁcation. Frequency bands can be created, by inserting the rotated U-shaped conductor-backed plane (CBP), and for proper controlling the both bands, the U-shaped strip is embedded on. The impedance matching of the antenna is enhanced by tuning and suitable adjusting dimensions of inserted U-shaped strip. Wider impedance bandwidth is obtained by using of ﬁnal structure of CBP, which provides a wide usable fractional bandwidth 21 % for 5 GHz WLAN and 52 % for X-band. The realized antenna has simple structure and compact size of 15 × 15 mm 2 , moreover, can provide good omni- directional radiation patterns. Measured and simulated results of the antenna with the different forms of CBP are presented. Keywords Dual bands · Microstrip fed antenna · Monopole · Wireless local area network 1 Introduction There is a prodigious increase in the applications that utilize wireless local area network technology and, the high data rate communications which has resulted in wireless devices T. Sedghi (B ) Young Researchers and Elite Club, Urmia Branch, Islamic Azad University, Urmia, Iran e-mail: Sedghi.tohid@gmail.com S. Shafei Young Researchers and Elite Club, Mahabad Branch, Islamic Azad University, Mahabad, Iran A. Kalami Department of Electrical Engineering, Urmia Branch, Islamic Azad University, Urmia, Iran T. Aribi Department of Electrical Engineering, Miandoab Branch, Islamic Azad University, Miandoab, Iran 123