A Hybrid Printed Monopole Antenna Loaded with Dielectric Resonator for Wideband and Circular Polarization Applications Osama M. Haraz, 1 Abdel-Razik Sebak, 1,3 Tayeb A. Denidni 2 1 Electrical and Computer Engineering Department, Concordia University, Montreal, QC, Canada H3G 2W1 2 Centre E ´ nergie Mat eriaux T el  ecommunications, Montr eal, QC, Canada H5A 1K6 3 KACST-RFTONICS, PSATRI, King Saud University, Riyadh, Saudi Arabia Received 18 July 2011; accepted 17 November 2011 ABSTRACT: This article presents a novel compact circularly polarized antenna with wide- band operation. The proposed antenna consists of a microstrip-line-fed printed monopole, a finite truncated ground, and a dielectric resonator (DR). Compared to the printed monopole antenna, the proposed DR-loaded antenna has an increased impedance bandwidth, a large axial ratio bandwidth, and a good realized gain across the desired frequency range. An antenna prototype is fabricated and experimentally tested. The measured antenna impedance match is better than À10 dB over 90% from 4.5 to 11.8 GHz frequency band and the 3-dB axial-ratio bandwidth is better than 35% covering the 5.4–7.65 GHz frequency band. V C 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 00:000–000, 2012. Keywords: printed monopole antennas; dielectric resonator antenna; hybrid antennas; dielectric- loaded antennas; wideband antennas I. INTRODUCTION The demand for wireless wideband communications is rapidly increasing due to the need to support more number of subscribers and to transfer more information with higher speeds and higher data rates. Design of wideband antennas becomes very essential for providing future wideband wireless communications. Many wideband wire- less communication devices require features of low- profile, small-size, low-cost, and omnidirectional radiation patterns. There are many different antenna designs devel- oped for wideband wireless applications. The dielectric resonator antenna (DRA) is considered an important solution to achieve both size reduction and bandwidth enhancement. DRAs have shown several unique character- istics rather than conventional metallic antennas; such as high radiation efficiency, low dissipation loss, small size, light weight, and low profile [1, 2]. In addition, DRAs have more degree of design flexibility than the regular antennas, which enable them to become perfect candidates for high efficiency, wideband, and cost-effec- tive applications. To enhance the bandwidth of the DRAs, many techni- ques have been proposed either by using some special composite DR structures [3–6], adopting special feeding mechanisms [7–9]. By using these methods, operation bandwidth ranges from 30 to 60% have been achieved. In radar, sensor, and imaging applications, when a sig- nal is transmitted through a wireless propagation channel, instantaneous time variations in both amplitude and phase happen, and these signals may be added together construc- tively or destructively from different multipath compo- nents. Fading is caused by multipath interference that occurs due to reflections or scattering from the nearby objects in the wireless propagation channel. To overcome multipath, improper line-of-sight between the transmitter and the receiver and some phasing issues due to rain or snow in the air, a circularly polarized (CP) antenna is required to ensure high-quality transmission or reception. In this article, a new design for a hybrid printed monopole antenna loaded with dielectric resonator (DR) for wideband circular polarization applications is pre- sented. The proposed antenna consists of a microstrip fed monopole printed on RT5880 substrate with a finite Correspondence to: O. M. Haraz; e-mail: o_ahm@encs.concordia.ca V C 2012 Wiley Periodicals, Inc. DOI 10.1002/mmce.20612 Published online in Wiley Online Library (wileyonlinelibrary.com). 1