IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 62, NO. 12, DECEMBER 2014 6049 Miniaturized Reconfigurable Multiband Antenna For Multiradio Wireless Communication Mojtaba Fallahpour, Member, IEEE, Mohammad Tayeb Ghasr, Senior Member, IEEE, and R. Zoughi, Fellow, IEEE Abstract—This paper introduces a general methodical approach for designing frequency reconfigurable antennas. This method was successfully used to design a novel coplanar waveguide (CPW)-fed slot frequency reconfigurable antenna capable of operating at four preselected frequency bands distributed over a wide fre- quency range from 59.5 MHz to 1000 MHz (i.e., 4 octaves of bandwidth) while keeping its overall size as small as possible. To add reconfigurablility to the antenna, optimally-designed and electronically-controllable PIN diode-loaded slots were used to strategically manipulate the flow of current path and consequently change the characteristics of the antenna. Designing for the lowest operating frequency (59.5 MHz), capacitor-loaded meandered slot lines and reconfigurable matching network were implemented to keep the size of the antenna as small as possible. The resulting overall size of the antenna is only where is calculated at 59.5 MHz. The measurement results verified that the antenna successfully operates at 59.25–59.75 MHz, 314–398 MHz, 430–496 MHz, and 792–950 MHz, all with an almost omnidirec- tional pattern and an acceptable gain. Index Terms—Miniaturization, multiradio wireless communica- tion, reconfigurable antennas, small antennas, software defined an- tennas, ultra-wideband antennas. I. INTRODUCTION T HERE is a growing interest in wireless communication market toward integrating more and more radios into a single chip (or single wireless platform) [1]. These multiradio platforms (e.g., laptop computer) require compact antennas op- erating over a wide range of frequencies, or antennas that can be tuned at those desired frequencies [1]. Relative form-factor (i.e., overall dimensions and bulkiness) prevents the use of many in- dividual antennas to address this problem. Wideband or ultra- wideband (UWB) antennas may be considered as a solution. Manuscript received March 10, 2014; revised August 24, 2014; accepted Oc- tober 17, 2014. Date of publication October 22, 2014; date of current version November 25, 2014. Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-10-2- 0077. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Govern- ment. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes not withstanding any copyright notation herein. M. Fallahpour is with the Electrical and Computer Engineering Department, University of Illinois at Urbana-Champaign, Champaign, IL 61801, USA (e-mail: mfallahpour@ieee.org). M. T. Ghasr and R. Zoughi are with the Applied Microwave Nondestruc- tive Testing Laboratory, Electrical and Computer Engineering Department, Mis- souri University of Science and Technology, Rolla, MO 65409, USA (e-mail: mtg7w6@mst.edu; zoughir@mst.edu). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TAP.2014.2364293 In the past several decades, much work has been done to de- velop wideband and UWB antennas for applications such as: high-resolution microwave imaging, short-range wireless com- munication systems, wireless body area network (WBAN), and electromagnetic compatibility measurements [2]–[5]. However, noise and interference issues along with large relative form- factor, limit the utility of wideband/UWB antennas for the mul- tiradio communication purposes [1]. As another potential solu- tion, multiband antennas, which can simultaneously cover some preselected and distinct bands [6]–[8], also suffer from noise and interference issues [1]. Additionally, when a desired op- erating frequency is relatively low [e.g., in the ultra-high-fre- quency (UHF) or very-high-frequency (VHF) regions], keeping the form-factor small becomes a challenge. In contrast, recon- figurable antennas are capable of addressing many of these lim- itations [1], [9]–[17]. A reconfigurable antenna can electron- ically or mechanically switch among different configurations to provide for a set of desired characteristics (e.g., matching over a range of frequency, pattern, and polarization). In com- parison with wideband antennas, reconfigurable antennas offer advantages such as: compact size, similar gain and radiation pat- tern for the preselected desired frequency bands, efficient use of electromagnetic spectrum, frequency selectivity useful for noise and interference reduction and polarization diversity [1], [14]. Despite these advantages, the topic of reconfigurable antennas is relatively new, and there is not a general, robust and method- ical design procedure for such antennas [15]. Moreover, to our knowledge, there are not many compact planar reconfigurable antennas which can cover preselected frequency bands in a rel- atively wide bandwidth. To this end, here we introduce a methodical approach for designing a reconfigurable antenna operating at several prese- lected frequency bands. Then, based on this design approach, the implementation of a novel coplanar waveguide (CPW)-fed reconfigurable antenna is given. The designed antenna covers four distinct preselected bands in the VHF/UHF regions. To add reconfigurablility to the antenna, optimally designed slots which are loaded with electronically controllable PIN diodes are used. Moreover, to extend the frequency of operation to below 100 MHz while keeping the form-factor of the antenna as small as possible, capacitor-loaded meandered slot lines and a reconfig- urable matching network are used. The overall size of the an- tenna is where is corresponding wave- length to the lowest operating frequency by the antenna (i.e., equivalent to ). Consequently, this design offers a significant improvement in comparison with other works (e.g., reported work in [18]) for miniaturization pur- poses in VHF band. Moreover, the covered distinct bands are 0018-926X © 2014 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.