ABSTRACT:A dual and wideband single-element rectangular dielectric resonator antenna (DRA) excited by a microstrip aperture is investigated experimentally. It provides two passbands in the ranges of 2. which
INTRODUCTIONThe dielectric resonator antenna (DRA) has been of great interest in the last two decades because of its various advantages, such as small size, light weight, low loss, low cost, and ease of excitation [1,2]. Although the relatively high bandwidth of the DRA is sufficient for many practical wireless communications, the use of multimedia utilities in mobile devices has demanded even wider bandwidths. In order to increase the DRA bandwidth, many techniques, such as stacking and parasitic-element methods, have been extensively explored [3,4]. Nevertheless, the abovementioned techniques require either more than one dielectric resonator or additional parasitic elements. Recently, the combination of DRA with other types of resonators such as microstrip patches and slots has been explored in order to achieve the dual-band feature. However, it is very difficult to achieve an impedance bandwidth of more than 10% (͉S 11 ͉ Ͻ Ϫ10 dB) over both the lower and upper bands of the IEEE802.11 for the DRA. For dualband wireless communications, it has been a new trend to combine two antennas into one, instead of making two separate antennas. Thus, it is highly desirable to use a single-element antenna to cover several allocated bands [9]. So far, there has been no singleelement DRA which can cover both the lower and upper bands of the IEEE802.11 WLAN simultaneously. In this paper, a simple rectangular DRA, which achieves wide bandwidth in the frequency ranges of 2.21-2.855 GHz (impedance bandwidth of 28%, ͉S 11 ͉ Ͻ Ϫ10 dB) and 4.835-5.455 GHz (impedance bandwidth of 11.9%, ͉S 11 ͉ Ͻ Ϫ10 dB), is investigated experimentally. The passbands of the proposed DRA are more than enough to cover the frequency requirements of the typical IEEE802.11 WLAN, which generally needs 2.400 -2.484 GHz in the lower band and 5.150 -5.350 GHz in the upper band. The proposed aperture-coupled rectangular DRA has a very simple structure, without the need of any parasitic elements. The return loss, antenna gain, and radiation patterns of the proposed DRA are measured. Broadside radiation patterns are found for the two passbands, and the co-polarized fields are generally 18-dB larger than the cross-polarized fields in the boresight direction.
ANTENNA CONFIGURATIONThe antenna configuration is shown in Figure 1, where the rectangular dielectric resonator ( r ϭ 6) of length L ϭ 40 mm, width W ϭ 30 mm, and height H ϭ 20 mm is fed by a rectangular slot of length L a ϭ 20.6 mm and width W a ϭ 2 mm, with a matching stub of length l s ϭ 7 mm. ECCOSTOCK HiK powder with dielectric constant r ϭ 6 was used as the dielectric material [10 -12], and hard-form clad boards ( r ϳ 1) were used to construct a rectangular container for the powder. A duroid substrate with dielectric constant 2.94 and thickness 0.762 mm was used, and a 50⍀ microstrip feedline of...
