Jeen-Sheen Row

Single-Fed Microstrip Patch Antenna With Switchable Polarization

A single-fed reconfigurable microstrip antenna that can provide various polarization diversities is presented in this paper. The antenna is excited by a microstrip feed line through aperture coupling. When two PIN diodes are used to respectively reconfigure the coupling slot and the open stub of the feed line, the polarization of the microstrip antenna can be switched between vertical and horizontal polarizations. For the reconfigurable antenna with the linear polarization diversity, it can be converted to a circularly-polarized antenna with switchable polarization sense by introducing a perturbation segment. Moreover, an antenna with the quadri-polarization diversity, including dual orthogonal linear polarizations and two circular polarizations, is also developed from the structure of the switchable circular polarization microstrip antenna, and only three diodes are required. Details of the antenna design are shown, and the measured results for the constructed prototype are also exhibited and discussed.

The design of a squarer-ring slot antenna for circular polarization

A new design of a circularly polarized square-ring slot antenna is proposed. The circular polarization is achieved by a series microstrip-line-feed configuration coupling to two orthogonal sides of the square-ring slot. A parametric study is conducted using a commercial simulation software based on the method of moments, and the design procedure is established. The required ground-plane size of the proposed design for a given frequency is also indicated. Three antenna prototypes respectively operated at distinct frequency bands are constructed and measured for providing the simulation validation. Experimental results show that the proposed antenna has good circularly polarized radiations and the 3 dB axial-ratio bandwidth is more than 6%.

Reconfigurable Square-Ring Patch Antenna With Pattern Diversity

A single-feed reconfigurable square-ring patch antenna with pattern diversity is presented. The antenna structure has four shorting walls placed respectively at each edge of the square-ring patch, in which two shorting walls are directly connected to the patch and the others are connected to the patch via pin diodes. By controlling the states of the pin diodes, the antenna can be operated at two different modes: monopolar plat-patch and normal patch modes; moreover, the 10 dB impedance bandwidths of the two modes are overlapped. Consequently, the proposed antenna allows its radiation pattern to be switched electrically between conical and broadside radiations at a fixed frequency. Detailed design considerations of the proposed antenna are described. Experimental and simulated results are also shown and discussed

A Compact Monopole Antenna for Super Wideband Applications

A planar microstrip-fed super wideband monopole antenna is initially proposed. By embedding a semielliptically fractal-complementary slot into the asymmetrical ground plane, a 10-dB bandwidth of 172% (1.44-18.8 GHz) is achieved with ratio bandwidth >;12:1. Furthermore, the proposed antenna also demonstrated a wide 14-dB bandwidth from 5.4 to 12.5 GHz, which is suitable for UWB outdoor propagation. This proposed antenna is able to cover the DVB-H in L-band (for PMP), DCS, PCS, UMTS, Bluetooth, WiMAX2500, LTE2600, and UWB bands.

Design of aperture-coupled annular-ring microstrip antennas for circular polarization

The design of an aperture-coupled annular-ring microstrip antenna for circular polarization (CP) is presented. The CP radiation of the annular-ring microstrip antenna is achieved by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The key parameters of the proposed design are investigated using a commercial simulation software based on the Method of Moments to show how to obtain the 50 /spl Omega/ input impedance and optimum axial ratio. The proposed design can be applied to the annular-ring microstrip antennas with different inner radii and substrate thickness, and several antenna prototypes are constructed and measured. Details of the experimental results of the CP performance are presented and discussed.

Circularly-Polarized Wide Slot Antenna Loaded With a Parasitic Patch

A design is described of a broadband circularly-polarized (CP) slot antenna. A conventional annular-ring slot antenna is first analyzed, and it is found that two adjacent CP modes can be simultaneously excited through the proximity coupling of an L-shaped feed line. By tuning the dimensions of this L-shaped feed line, the two CP modes can be coupled together and a broad CP bandwidth is thus formed. The design method is also valid when the inner circular patch of the annular-ring slot antenna is vertically raised from the ground plane. In this case, the original band-limited ring slot antenna is converted into a wide-band structure that is composed of a circular wide slot and a parasitic patch, and consequently the CP bandwidth is further enhanced. For the patch-loaded wide slot antenna, its key parameters are investigated to show how to couple the two CP modes and achieve impedance matching. The effects of the distance between the parasitic patch and wide slot on the CP bandwidth and antenna gain are also presented and discussed in details.

Dual-frequency triangular planar inverted-F antenna

This paper presents the performance of a single-feed triangular planar inverted-F antenna with a V-shaped slot. Several prototypes of the proposed antennas with different shorting-wall widths are studied experimentally. The obtained results show that, by selecting a proper shorting-wall width, the proposed antenna not only has dual-frequency characteristic but also can achieve the impedance bandwidth of more than 30% in higher operating frequency band. In addition, the radiation pattern across the entire operating bandwidth is measured and discussed.

A wide-band monopolar plate-patch antenna

A new design of a monopolar plate-patch antenna is proposed and experimentally studied. The proposed antenna is a planar rectangular monopole top-loaded with a shorted square or circular patch, which is shorted to the antenna ground by two ground plates placed symmetrically on each side of the planar monopole. Prototypes have been constructed and experimental results show, that with an antenna height less than 10% of the free-space wavelength of the center operating frequency, the proposed antenna can have a monopole radiation pattern with an impedance bandwidth larger than three times that of a corresponding monopolar wire-patch antenna.

Circular Polarization and Polarization Reconfigurable Designs for Annular Slot Antennas

A simple design for circularly-polarized (CP) annular slot antennas is first described. The antenna is fed by a V-shaped coupling strip loaded with a small resistance, and it can generate CP radiation as long as the inclined angle of the V-shaped coupling strip is properly adjusted. Numerical analyses to the effects of varying the angle on CP axial ratio are performed. Several CP prototypes are fabricated. Both simulated and measured results demonstrate that the proposed feeding mechanism can give good CP performances for the case that the slot width is varied from 0.008 to 0.09 λ0. Then, a design for polarization reconfigurable antennas is developed from the feeding mechanism. Only two PIN diodes are involved in the reconfigurable design that can offer the switching among three different polarizations, including one linear polarization and dual orthogonal circular polarizations. Details of the designs and experimental results are shown.

Polarization-Diversity Ring Slot Antenna With Frequency Agility

A design for polarization-diversity slot antennas with switchable frequency is described. The antenna structure is mainly composed of a radiating annular slot backed with a reflector and a quasi-lumped coupler with two different operating modes, quadrature hybrid mode and T-junction power divider mode. The resonant frequency of the slot antenna and the operating frequencies of the two modes of the coupler can be tuned with variable capacitors. First, the effects of changing capacitance values on the performances of the antenna and coupler are respectively analyzed. Then, according to the simulation results, validated with experiments, a reconfigurable antenna prototype integrating with several diodes and their related dc-bias networks is constructed. The prototype is designed to be with three working frequencies, and moreover it can provide one linear polarization and two circular polarizations at each working frequency. Details of measured antenna performances are shown.