0018-926X (c) 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TAP.2016.2575980, IEEE Transactions on Antennas and Propagation > AP1506-0908.f < 1 Abstract—Designs of novel magnetoelectric dipole antennas excited by dual open-ended slots for both single and dual linear polarizations are presented in this paper. The antenna can be interpreted as a dual complementary source which exhibits lower profile and higher gain while maintaining excellent radiation characteristics of the original ME dipole, including wideband, low back radiation and high polarization purity. In addition, high isolation is obtained in the dual polarization design. All the above characteristics show that the proposed antennas can be regarded as potential candidates for various wireless applications. Prototypes are fabricated and measured to confirm the simulation results. Index Terms—Complementary antenna, dual source, high gain, high isolation, low back radiation, low profile, wideband I. INTRODUCTION N order to provide high data rate, reliable and secure wireless communication channels for mobile users, the performances of base station antennas are very important. Conventional antennas, such as log-periodic, horn and reflector, have shown excellent radiating performance; however, their common disadvantage is bulky in size [1]. Patch antennas are popular due to low profile and simple structure. Their impedance bandwidths can be enhanced to over 30% by applying well-known wideband techniques [2] - [8]. Unfortunately, they still have disadvantages in asymmetric radiation pattern [2], [3], large gain variation within the operating frequency band [2] - [5] or high back radiation [6] - [8]. In general, antenna thickness, bandwidth, gain, polarization purity, and the stability of the radiation pattern need to be considered simultaneously for base station antenna design. Dipole antennas are widely applied to base station antenna designs [9] - [11] as they are wideband and stable in gain. By applying the complementary source concept [12], several magnetoelectric (ME) dipole antennas are designed [13] - [15] to exceed the performance of the directed-dipole antenna. ME dipole antennas have characteristics of wideband, low cross This project was fully supported by the Innovation and Technology Commission, The Government of the Hong Kong Special Administration Region (No: ITS/459/09FP). H. W. Lai and K. K. So are with the State Key Laboratory of Millimeter Waves, City University of Hong Kong, Hong Kong SAR (e-mail: hwlai@ieee.org; eekkso@cityu.edu.hk). H. Wong, C. H. Chan and K. M. Luk are with the State Key Laboratory of Millimeter Waves and Department of Electronic Engineering, City University of Hong Kong, Hong Kong SAR (e-mail: hang.wong@cityu.edu.hk, eechic@cityu.edu.hk, eekmluk@cityu.edu.hk). polarization levels and high front-to-back ratio. They can be modified to perform different characteristics, such as dual band [16]-[17], dual-polarization [18]-[20], circular polarization [21]-[22], ultra-wideband [23], pattern diversity [24], low profile [25]-[26], and wide beam width [27], [28]. Since the first ME dipole antenna proposed in 2006 [13], all the ME-dipole designs in the literature are interpreted as only one complementary source, which consists of one electric dipole and one magnetic dipole. In this paper, the proposed ME-dipole will be interpreted as two complementary sources. It is found that this dual complementary source magnetoelectric (DCS-ME) dipole antenna can perform wideband, high gain, low profile, high polarization purity and high front-to-back ratio simultaneously. High isolation is achieved for the dual polarization structure as well. These advanced performances cannot be achieved at the same time by the conventional ME dipoles. This paper is organized as follows. Section II discusses the principal of the DCS-ME dipole. Section III introduces the geometry and provides the results of a linearly polarized Magnetoelectric Dipole Antennas with Dual Open-ended Slot Excitation Hau Wah Lai, Senior Member, IEEE, Kwok Kan So, Senior Member, IEEE, Hang Wong, Senior Member, IEEE, Chi Hou Chan, Fellow, IEEE and Kwai Man Luk, Fellow, IEEE I (a) (b) Complementary source 1 Complementary source 2 y x z J  1 M  1 J  2 M  2 Complementary source y x z J  M  Fig. 1. Principle of operation of (a) original magnetoelectric dipole antenna with single excitation (b) proposed magnetoelectric dipole antenna with dual excitation. Vertical portions Ground plane Vertical portions Ground plane