R. Chair

Miniature wide-band half U-slot and half E-shaped patch antennas

The U-slot patch antenna, a single-layer single-patch antenna on a relatively thick substrate (/spl sim/0.08/spl lambda//sub 0/), is a wide-band antenna with an impedance bandwidth in a range of 20%-30%, which is about an order of magnitude larger than that of the regular patch antenna. Recently, it was shown that a half U-slot patch antenna, with half of one of the dimensions of the U-slot patch, maintains similar wide-band behavior. The half-structure was also successfully applied to the U-slot with shorting wall. In this paper, new results on half structures, not previously published, are presented. First, the shorting pin technique is used to reduce the size of the half U-slot patch antenna. By both simulation and experimental studies, it is concluded that the impedance bandwidths, radiation patterns, radiation efficiencies and gains of the half-structures are comparable to the corresponding full structures. Bandwidth of 28.6% and radiation efficiencies exceeding 90% are obtained for the half U-slot patch with shorting pin. Radiation patterns are stable across the matching band. Second, it is shown that a structure obtained from halving the E-shaped patch, which is a derivative of the U-slot patch, also maintains its wide-band behavior.

Aperture fed wideband circularly polarized rectangular stair shaped dielectric resonator antenna

A circularly polarized rectangular stair shaped dielectric resonator antenna (DRA) is presented. The DRA is excited by a narrow rectangular slot and rotated 45/spl deg/ with respect to the sides of the DRA to generate circular polarization. A parametric study of the length to width ratio to optimize the axial ratio bandwidth is given. A 3 dB axial ratio bandwidth of 10.6% is achieved when the length to width ratio is 1.9.

MICROSTRIP LINE AND CPW FED ULTRA WIDEBAND SLOT ANTENNAS WITH U-SHAPED TUNING STUB AND REFLECTOR

MICROSTRIPLINEANDCPWFEDULTRAWIDEBANDSLOTANTENNASWITHU-SHAPEDTUNINGSTUBANDREFLECTORR.Chair,A.A.Kishk,K.F.Lee,C.E.Smith,andD.KajfezDepartmentofElectricalEngineeringCenterforAppliedElectromagneticSystemsResearch(CAESR)UniversityofMississippiUniversity,MS38677,USAAbstract—Widebandprintedrectangularslotantennasbackedwithreflectorsforunidirectionalradiationpatternsareinvestigated. AU-shaped tuning stub is used to improve the matching. Two differentfeeding mechanisms are introduced. A rectangular slot excited bymicrostriplinefeedwithaU-shapedtuningstubgivesanimpedancebandwidth of 110% (

Wideband simple cylindrical dielectric resonator antennas

Bandwidths of the coaxial fed and aperture coupled cylindrical dielectric resonator antennas (DRAs) with broadside radiation patterns are enhanced by exciting the HEM/sub 11/spl Delta// (1</spl Delta/<2) mode at a frequency close to the HEM/sub 11/spl delta// (0</spl delta/<1) mode. Both HEM/sub 11/spl delta// and HEM/sub 11/spl Delta// modes have similar broadside radiation patterns. Measured impedance bandwidths as much as 26.8% (S/sub 11/<-10 dB) are achieved for the coaxial fed DRA and 23.7% for the aperture coupled DRA. These bandwidths are comparable to those obtained using stacked DRAs. The resonant frequency of the HEM/sub 11/spl Delta// mode can be adjusted by the radius (r) to height (h) ratio of the cylindrical DRA. A wide bandwidth is obtained when this ratio equals to 0.329.

Study on Sequential Feeding Networks for Subarrays of Circularly Polarized Elliptical Dielectric Resonator Antenna

Circularly polarized (CP) dielectric resonator antenna (DRA) subarrays have been numerically studied and experimentally verified. Elliptical CP DRA is used as the antenna element, which is excited by either a narrow slot or a probe. The elements are arranged in a 2 by 2 subarray configuration and are excited sequentially. In order to optimize the CP bandwidth, wideband feeding networks have been designed. Three different types of feeding network are studied; they are parallel feeding network, series feeding network and hybrid ring feeding network. For the CP DRA subarray with hybrid ring feeding network, the impedance matching bandwidth (S11<-10 dB) and 3-dB AR bandwidth achieved are 44% and 26% respectively

Measurement and analysis of miniature multilayer patch antenna

Although the microstrip patch antenna has a number of advantages such as low-cost and light weight, its physical size is quite large at low microwave frequencies. The designs of multilayer miniature patch antennas with coaxial feed are presented. The first design is a rectangular two-layer patch antenna. Measured results and the results of a preliminary analysis are presented. The projection area of the two-layer patch antenna is kept the same as the single-layer rectangular patch antenna. The resonant frequency of the two-layer antenna is reduced by 50% and has bandwidth of 5%, which is wider than the single-layer rectangular patch antenna. In the second design, the upper patch is cut into a bow-tie shape. This results in a 60% reduction in resonant frequency and a 12% bandwidth. Both the two-layer rectangular and the two-layer bow-tie antennas have good radiation patterns, with cross-polarization level lower than the copolarization level by more than 20 dB.

Small-size wide-bandwidth microstrip patch antennas

In many applications in wireless communications, it is desirable to use microstrip patch antennas which are small in size but have bandwidths in excess of 10%. There are three common methods of reducing the patch size: (1) the use of microwave substrates with large permittivities; (2) the use of shorting walls; and (3) the use of shorting pins. When applied to the regular patch, the resulting small-size antenna usually has only a few percent bandwidth, not enough to meet the requirement of many applications. In this paper, we apply the three size reduction techniques to two wideband patch antennas - the U-slot patch and the L-probe patch. Simulation results using ENSEMBLE 6.0 are presented first, followed by some measured results.

Comparative study on the mutual coupling between different sized cylindrical dielectric resonators antennas and circular microstrip patch antennas

A systematic comparative study on the mutual coupling (S/sub 21/) between dielectric resonator antennas (DRAs) and microstrip patch antennas is presented. The mutual coupling between two cylindrical probe-fed DRAs is studied for different radius to height (a/L) ratios. It is found that the mutual coupling decreases with the radius to height ratio. Comparison between mutual coupling of probe-fed cylindrical DRAs and circular microstrip patch antennas with different dielectric substrates are also studied. The mutual coupling between DRAs is 2 dB stronger than between microstrip patch antennas when the patch is etched on a dielectric substrate of a dielectric constant close to the permittivity of the DRA. The mutual coupling of the circular patch antennas reduces with the dielectric constant of the substrate.

Comparative Study on Different Feeding Techniques for Dual Polarized Dielectric Resonator Antennas

Here, we design and analyze several dual polarized dielectric resonator antennas (DRA) excitation techniques and compare their advantages and disadvantages. A simple cylindrical disk DRA is used. It is designed to resonate around 10 GHz. The feeding mechanisms include probe excitation, aperture couple excitation and co-planar waveguide (CPW) feed. In addition, we also discuss combinations of different feeding mechanisms, such as probe/aperture or aperture/CPW. The comparisons are based on resonant frequency, common matching bandwidth (S11 < -10 dB), isolation and radiation pattern symmetry

Broadband dielectric resonator antennas excited by L-shaped probe

Dielectric resonator antennas (DRA) designed for broadband applications and excited by L-shape probe are analyzed numerically. The L-probe is housed under a free space groove between the DRA and the ground plane. A 32% matching bandwidth is achieved with broadside radiation patterns. The new structure is mechanically better than other wideband DRA antennas.