Planar elliptical antenna for ultra-wideband communications

Abstract

notched band shifts toward the lower-frequency range significantly and has a wider notch bandwidth as the slot length lengthens. It is found that by adjusting the mean length of the slot to be about one half-wavelength at the desired notched frequency, a destructive interference can take place, thus causing the antenna to be nonresponsive at that frequency. Figure 3 shows the slot-width effect on the notched band. By adjusting the width of the embedded slot, the lengths of the outer and inner perimeters of the embedded slot control the lower-and upper-edge frequencies of the notched band, respectively. It is obvious that the notched bandwidth is increased with increasing slot width. Thus, we can have a specific notched band by changing the slot length and width. The corresponding data are also listed in Tables 1 and 2 for comparison. The measured gains in the boresight direction with respect to frequency are shown in Figure 4. This characteristic meets the requirement of the multiband OFDM physical-layer proposal for IEEE 802.15.3a. And, there is a notched-band between 4.799 and 5.999 GHz, suppressed by the loaded slot, which meets the need for interference immunity with HIPERLAN and WLAN. CONCLUSIONA novel microstrip-line-feed elliptical antenna with a bandnotched characteristic has been proposed and investigated. The proposed antenna provides ultra-wideband characteristics in a planar structure using the simple impedance-matching technique. By adjusting the loaded slot, it can obtain the desired band-notched characteristic. This antenna design is a breakthrough for selecting the notched band and can be directly applied to UWB communications where the band-notched characteristic is needed. INTRODUCTIONA reflectarray is a type of antenna that combines the best features of conventional reflectors with those of microstrip phased arrays. In this structure, a horn or small antenna array illuminates a planar array of printed radiators which, by using suitable phasing circuits, converts an incident spherical wave into a plane wave, collimating the reflected field in a desired direction [1]. Their low cost, flatness, and ease of installation and manufacture convert these structures into ideal solutions to be used as narrow-beam antennas in modern communication systems [2]. Moreover, the spatial signal distribution permits to eliminate the complexity and losses associated to the microstrip-feed distribution network. Depending on the phase-shift distribution it is possible to produce a pencil-beam or a shaped-beam radiation pattern. There are different ways to achieve the required phase-shift per cell, in [3], equal-size patches are employed with passive delay lines of different lengths while in [4] the phase of the scattered field is controlled by means of the patch size. Although these methods assure the correct antenna performance in a desired direction do not permit control of the phase shift between the patches and, consequently, to steer the pencil beam. Fig. 3 ( r ‫؍‬ 4.4, h ‫؍‬ 0.8 mm, r a ‫؍‬ 11 mm, r The pos...

Ultra-Wideband Antenna and Design

“…i.e., Huang et al [28,29] introduced an impedance matching technique by cutting a notch at the ground plane, and the impedance bandwidth can be enhanced by suitable size and position of notch chosen. Azim et al [30] proposed to improve the impedance bandwidth by cutting triangular shaped slots on the top edge of the ground plane.…”

Multiband Monopole Antenna with Sector-Nested Fractal

“…There are many methods proposed to realize the miniaturization characteristic of the antennas, including resonant units [1] [2], different patterns [2] [3], antenna loading [4], surface of the slot [5], electronic reconfigurable [6], and adopting reconstructed structure [7]. These methods are so specialized that only some aspects of the demand can be met, while the overall performance of the antenna is decreased in order to satisfy the communication system.…”

Dual Band-Notched Antenna With the Parasitic Strip for Uwb

“…Since the U.S. Federal Communication Commission (FCC) authorized the unlicensed use of the ultra wideband (UWB) in 3.1-10.6 GHz in February 2002, significant research activities and interests have been aroused in academic and industrial fields recently to explore various UWB antennas [1][2][3][4][5][6]. However, the frequency range for UWB systems approved by the FCC between 3.1 to 10.6 GHz will cause interference to the existing wireless communication systems, such as the IEEE 802.…”