6 IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 8, 2009
Compact Dual-Band Hybrid Dielectric Resonator
Antenna With Radiating Slot
Yi-Fang Lin, Hua-Ming Chen, Senior Member, IEEE, and Chia-Ho Lin
Abstract—A miniature independent dual-band hybrid dielectric
resonator antenna (DRA) fed by a coplanar waveguide (CPW) in-ductive slot is proposed. In this configuration, the CPW inin-ductive slot performs the functions of an effective radiator and the feeding structure of the DR. By optimizing the structure parameters, the hybrid structure resonates at two different frequencies indepen-dently. One is from the DRA with the broadside patterns and the other from the inductive slot with the dipole-like patterns. In order to determine the performance of varying design parameters on bandwidth and resonance frequency, parametric study is carried out using simulation software HFSS and experimental results. The measured and simulated results show excellent agreement.
Index Terms—Ceramic dielectric material, coplanar waveguide
(CPW)-fed, dual-band, hybrid dielectric resonator antenna (DRA).
I. INTRODUCTION
T
HE dielectric resonator antenna (DRA) [1], [2] has been of interest due to their low loss, high permittivity, light weight and ease of excitation. In addition, wide bandwidth, low dissipation loss at high frequency, and high radiation efficiency due to the absence of conductors and surface wave losses are inherent advantages of DRAs. In the past few years, theoretic and experimental investigations have been reported by many researchers on DRAs of cylindrical, rectangular, and hemispherical shapes [1]–[16]. The use of dielectric resonators in feeding circuits requires accurate knowledge of the cou-pling between the resonator and circuits. In order to match the DR to the feed line and to excite the desired mode in the resonator, the most common method of feeding techniques is aperture-coupled arrangement [3]–[6]. Recently, hybrid dielec-tric resonator antennas have attracted extensive attentions due to their dual-band and wideband operation without increasing antenna volume. The hybrid structure can be considered as the combination of a DRA and another radiating resonator of the resonant feeding structure. These two radiating resonators are tightly stacked together and resonate at different frequencies. By arranging for the radiating resonators’ position, a compact dual-band [7]–[9] or wideband [10]–[16] hybrid DRA can be designed. However, the resonant feeding structure adopted inManuscript received June 04, 2007; revised November 27, 2007. First pub-lished June 10, 2008; current version pubpub-lished March 31, 2009. This work was supported by the National Science Council of Taiwan under Contract NSC 95-2221-E-151-017.
The authors are with the Institute of Photonics and Communications, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan (e-mail: [email protected]; [email protected]).
Color versions of one or more of the figures in this letter are available online at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/LAWP.2007.914118
Fig. 1. Top view and side view of the dual-frequency compact hybrid resonator antenna.
these reported designs such as microstrip-fed aperture-coupled, loop slot or coplanar waveguide (CPW)-fed slot arrangement offer more flexibility and is directly compatible with different mounting surfaces. The CPW transmission lines have been widely used as feeding networks and have many useful design characteristics such as low radiation leakage, less dispersion, little dependence of the characteristic impedance on substrate height, and uniplanar configuration. There are two kinds of coupling mechanism for CPW-fed line, one is shorted-end coupling slot (inductive) and the other is open-end coupling slot (capacitive). They also allow easy mounting and integration with other microwave integrated circuits and RF frequency device.
In this letter, in order to avoid via holes and for ease of fab-rication, the coplanar waveguide feed to DRA is adopted as shown in Fig. 1. The CPW inductive slot is used as the DR feeding structure and acts as an effective radiator at the same time. This design has the advantage of simple structure and com-pact size. Most importantly, the hybrid antenna can not only achieve dual-band with different radiating patterns but also the two bands can be independently designed. These proposed DR antennas are suitable to be mounted above the system circuit board of the mobile communication device, and are very suit-able for application in mobile communication systems.
LIN et al.: COMPACT DUAL-BAND HYBRID DRA WITH RADIATING SLOT 9
Fig. 8. Measured and simulatedx-z plane and y-z plane radiation patterns at 3.45 GHz.
Fig. 9. Measured and simulatedx-z plane and y-z plane radiation patterns at 4.8 GHz.
in the -plane are near omnidirectional when compared to the conventional dipole antenna because the asymmetric DR loading on the CPW inductive slot. In addition, the proposed antenna radiates a maximum in the broadside direction in the - and -planes at 4.8 GHz, which corresponding to the far-field radiation from the resonant mode of the DRA and as shown in Fig. 9. It should be mentioned that the radiating patterns in the two planes along the back side have large back radiation, which is because of the effect of bidirectional radia-tions for the slot antenna. Fig. 10 presents the measured antenna gain in the broadside direction throughout the two frequency bands. The measured gain was obtained using the gain transfer method where a standard gain horn antenna was used as a reference. The measured peak gain is about 4.7 dBi in the 3.45-GHz band, and in the 4.8-GHz band, the antenna peak gain is about 5.6 dBi, and all the gain variations are small.
V. CONCLUSION
A miniature independent dual-band hybrid dielectric res-onator antenna fed by a coplanar waveguide inductive slot has been proposed and tested. A parametric study is carried out to investigate the antenna design parameters. The prototype has been designed and fabricated and found to have a bandwidth and antenna gain of 9%, 4.7 dBi and 4.8%, 5.6 dBi at the resonant frequencies of 3456 and 4797 MHz, respectively. The proposed antenna has a small size, effective feeding structure,
Fig. 10. Measured antenna gain of the hybrid antenna in the broadside( = 0 ).
and adequate operational bandwidth, such that it is suitable for use in communication system applications.
REFERENCES
[1] D. Kajfez and P. Guillon, Dielectric Resonators. Norwood, MA: Artech House, 1986.
[2] K. M. Luk and K. W. Leung, Dielectric Resonator Antennas. Hert-fordshire, U.K.: Research Studies, 2003.
[3] R. N. Simons and R. Q. Lee, “Effect of parasitic dielectric resonator on CPW/aperture-coupled dielectric resonator antenna,” Inst. Elect. Eng.
Proc.-Microw. Antennas Propag., vol. 140, pp. 336–338, 1993.
[4] R. K. Mongia and A. Ittipiboon, “Theoretical and experimental investi-gations on rectangular dielectric resonator antennas,” IEEE Trans.
An-tennas Propag., vol. 45, no. 9, pp. 1348–1356, Sep. 1997.
[5] M. S. A. Salameh, Y. M. M. Antar, and G. Seguin, “Coplanar-wave-guide-fed slot-coupled rectangular dielectric resonator antenna,” IEEE
Trans. Antennas Propag., vol. 50, no. 10, pp. 1415–1419, Oct. 2002.
[6] H. Y. Lam and K. W. Leung, “Analysis of U-slot-excited dielectric res-onator antennas with a backing cavity,” Inst. Elect. Eng. Proc.-Microw.
Antennas Propag., vol. 153, pp. 480–482, 2006.
[7] T. A. Denidni and Q. Rao, “Hybrid dielectric resonator antenna with radiating slot for dual-frequency operation,” IEEE Antennas Wireless
Propag. Lett., vol. 3, pp. 321–323, 2004.
[8] A. B. Buerkie, K. Sarabandi, and H. Mosllaei, “Compact slot and di-electric resonator antenna with dual-resonance, broadband character-istics,” IEEE Trans. Antennas Propag., vol. 53, no. 3, pp. 1020–1027, Mar. 2005.
[9] Q. Rao, T. A. Denidni, A. R. Sebak, and R. H. Johnston, “Compact independent dual-band hybrid resonator antenna with multifunctional beams,” IEEE Antennas Wireless Propag. Lett., vol. 5, pp. 239–242, 2006.
[10] Z. N. Chen, K. Hirasawa, K. W. Leung, and K. M. Luk, “A new inverted antenna with a ring dielectric resonator,” IEEE Trans. Veh. Technol., vol. 48, no. 4, pp. 1029–1032, Jul. 1999.
[11] K. P. Esselle and T. S. Bird, “A hybrid-resonator antenna: Experi-mental results,” IEEE Trans. Antennas Propag., vol. 53, no. 2, pp. 870–871, Feb. 2005.
[12] K. Lan, S. K. Chaudhuri, and S. Safavi-Naeini, “Design and analysis of a combination antenna with rectangular dielectric resonator and in-verted L-plate,” IEEE Trans. Antennas Propag., vol. 53, no. 1, pt. 1, pp. 495–501, Jan. 2005.
[13] Y. Gao, B. L. Ooi, W. B. Ewe, and A. P. Popov, “A compact wideband hybrid dielectric resonator antenna,” IEEE Microw. Wireless Compon.
Lett., vol. 16, no. 4, pp. 227–229, Apr. 2006.
[14] Y. Gao, A. P. Popov, and B. L. Ooi, “Experimental study of wideband hybrid dielectric resonator antenna on small ground plane,” Electron.
Lett., vol. 42, no. 13, pp. 731–733, Jun. 2006.
[15] J. Janapsatya, K. P. Esselle, and T. S. Bird, “Compact wideband di-electric-resonator-on-patch antenna,” Electron. Lett., vol. 42, no. 19, pp. 1071–1072, Sep. 2006.
[16] K. K. So and K. W. Leung, “Bandwidth enhancement and frequency tuning of the dielectric resonator antenna using a parasitic slot in the ground plane,” IEEE Trans. Antennas Propag., vol. 53, no. 12, pp. 4169–4172, Dec. 2005.
