Fuguo Zhu

Multiple Band-Notched UWB Antenna With Band-Rejected Elements Integrated in the Feed Line

To mitigate potential interferences with coexisting wireless systems operating over 3.3-3.6 GHz, 5.15-5.35 GHz, or 5.725-5.825 GHz bands, four novel band-notched antennas suitable for ultra-wideband (UWB) applications are proposed. These include UWB antennas with a single wide notched band, a single narrow notched band, dual notched bands, and triple notched bands. Each antenna comprises a half-circle shaped patch with an open rectangular slot and a half-circle shaped ground plane. Good band-notched performance is achieved by using high permittivity and low dielectric loss substrate, and inserting quarter-wavelength horizontal/vertical stubs or alternatively embedding quarter-wavelength open-ended slots within the feed line. The results of both simulation and measurement confirm that the gain suppression of the single and multiple band-notched antennas in each desired notched band are over 15 dB and 10 dB , respectively. The radiation pattern of the proposed triple band-notched design is relatively stable across the operating frequency band.

LOW-PROFILE DIRECTIONAL ULTRA-WIDEBAND ANTENNA FOR SEE-THROUGH-WALL IMAGING APPLICATIONS

A compact-size planar antenna with ultra-wideband (UWB) bandwidth and directional patterns is presented. The antenna can be fabricated on a printed circuit board (PCB). On one side of the PCB, it has a circular patch, and on the other side it has a slot-embedded ground plane with a fork-shaped feeding stub in the slot. Directional radiation is achieved by using a reflector below the antenna. To reduce the thickness of the antenna, a new low-profile antenna configuration is proposed. Three types of directional UWB antennas are analyzed. The distance between the antenna and the reflector is 12 mm (0.16 λ0, λ0 is the free space wavelength at the lowest frequency). In order to validate the design, a prototype is also fabricated and measured. Measured results agree well with the simulated ones. The measured results confirm that the proposed antenna features a reflection coefficient below -10 dB over the UWB range from 4.2 GHz to 8.5 GHz, a maximum gain around 9 dBi, a front-to-back ratio over 17 dB and pulse fidelity higher than 90% in the time domain. Thus it is promising for see-through-wall imaging applications.

Design and Analysis of Planar Ultra-Wideband Antenna with Dual Band-Notched Function

A novel planar ultra-wideband (UWB) antenna with dual band-notched characteristics is proposed. The antenna is fabricated on a printed circuit board (PCB), having a circular monopole and arc-shaped parasitic strips on one side and a ground plane with a slot aperture on the other side. Two narrow bands at 5.15-5.35 GHz and 5.725-5.825 GHz are notched by using two arc-shaped parasitic strips on the same layer of the radiator. Compared with other band-notched UWB antennas, the proposed antenna exhibits the advantages of simple structure, compact size, simple control of each notched frequency band using separate parasitic strips, and good performance. Surface current distributions and equivalent circuit model are applied to analyze the operating principle of the proposed antenna. To validate the concept, a prototype is fabricated and tested. Both simulated and measured results confirm that the proposed antenna achieves a wide bandwidth from 3.1 GHz to 10.6 GHz with two narrow bands notched successfully. The results of VSWR, radiation patterns and gain response are shown and discussed in detail. The antenna enables the independent control of the notched frequency bands, and the proposed method can be extended for designing planar UWB antennas with multiple band-notched characteristics and reconfigurable notched frequency.

A Simple and Compact Planar Ultra Wideband Antenna with Single or Dual Band-Notched Characteristics

A printed monopole ultra wideband (UWB) antenna with frequency band-notched characteristics is proposed and investigated. The antenna consists of a half-disk shaped structure combined with an inverted isosceles trapezoid structure. To achieve the frequency band notched characteristics, an open-ended thin slit with a length of about one quarter guided wavelength is inserted on the radiator. Multiple slits can be employed to realize multiple frequency band notched characteristics. To validate the concept, two prototypes aredesigned, fabricated and tested. The ¯rst is a single band notched UWB antenna whereas the second is a dual band notched UWB antenna. The simulated and measured results of both antennas are presented shown a reasonable agreement between them. The results also con¯rm the proposed UWB antenna design can achieve superior dual band-notch performance at desired frequency bands. 1

Ultra-Wideband Dual-Polarized Patch Antenna With Four Capacitively Coupled Feeds

A novel dual-polarized patch antenna for ultra-wideband (UWB) applications is presented. The antenna consists of a square patch and four capacitively coupled feeds to enhance the impedance bandwidth. Each feed is formed by a vertical isosceles trapezoidal patch and a horizontal isosceles triangular patch. The four feeds are connected to the microstrip lines that are printed on the bottom layer of the grounded FR4 substrate. Two tapered baluns are utilized to excite the antenna to achieve high isolation between the ports and reduce the cross-polarization levels. In order to increase the antenna gain and reduce the backward radiation, a compact surface mounted cavity is integrated with the antenna. The antenna prototype has achieved an impedance bandwidth of 112% at (|S11 | ≤ -10 dB) whereas the coupling between the two ports is below -28 dB across the operating frequency range. The measured antenna gain varies from 3.91 to 10.2 dBi for port 1 and from 3.38 to 9.21 dBi for port 2, with a 3-dB gain bandwidth of 107%.

Miniaturized Tapered Slot Antenna With Signal Rejection in 5–6-GHz Band Using a Balun

A miniaturized elliptically tapered slot antenna fed by a novel balun is proposed for directional ultrawideband (UWB) applications. The feeding configuration consists of a stepped microstrip line and a folded slotline connected with a circular slot. An arc-shaped parasitic strip is printed inside the circular slot. This design achieves the minimization of the physical size and the capability of signal rejection at 5-6 GHz with significant gain suppression of 15 dB. Both simulated and measured results confirm the advantage of the design in reducing the size of the antenna while maintaining the UWB performance with band-notched function.

A Planar Integrated Folded Reflectarray Antenna With Circular Polarization

This communication presents the complete design of a circularly polarized (CP) folded reflectarray (FRA) antenna with an integrated planar structure for the first time in the open literature. To achieve circularly polarized, a printed meander-line polarizer is designed and integrated with the linearly polarized (LP) FRA. To achieve a low-profile planar structure, an integrated 2×2 planar array is designed as the feed source instead of a horn. Thus, the whole antenna, including the feed source, LPFRA, and meander-line polarizer, can be fully integrated and fabricated using low-cost printed circuit board technology. To validate the concept, a right-handed CPFRA operating in C-band is designed, fabricated, and measured. The broadside axial ratio (AR) of the proposed CPFRA is lower than 1 dB over a bandwidth from 5.22 to 5.46 GHz. In addition, the maximum gain of 22.8 dBic is obtained at 5.38 GHz with the antenna efficiency of 27%. The antenna is promising for applications in satellite communication due to advantages of low profile, easy fabrication, low cost, and high gain.

Investigation of dual-polarized ultra-wideband antenna with directional patterns

The design and study of multi-port single and dual-polarized ultra-wideband (UWB) antennas has been investigated in this paper. Each UWB element consists of a slotted ground plane which is fed by a L-shaped stepped microstrip line to achieve a wide bandwidth. A dumbbell-shaped slot is embedded in the ground plane to improve the impedance matching across the wide frequency range. To achieve dual orthogonal polarizations, a dual-element structure has been employed by rotating one element 90 degrees. Moreover, the four-port dual-polarized UWB antenna has been obtained by adding another two elements which enables symmetrical radiation patterns. A compact cavity has been utilized to reduce the backward radiation and enhance the front-to-back ratio (FBR). The results have confirmed that, the obtained antennas can achieve a wide frequency band from 3 to over 10 GHz.

Design and Investigation of Differential-Fed Ultra-Wideband Patch Antenna with Polarization Diversity

A novel single- or dual-polarized ultra-wideband (UWB) patch antenna fed by coupled feeding mechanism is proposed. The single-polarized antenna consists of a square ring patch and two Γ-shaped patches which are coupled to the radiating patch. The vertical portions of the Γ-shaped patches are connected to the microstrip lines which are printed on the bottom layer of the grounded FR4 substrate. To realize the differential feeding mechanism for enhancing the polarization purity, a tapered balun is employed to excite the antenna. Further to provide dual linear orthogonal polarizations, another pair of Γ-shaped patches is added in the single-polarized UWB antenna. The dual-polarized UWB antenna prototype can achieve two orthogonal polarizations with an impedance bandwidth ( dB) of 113% and isolation of over 25 dB across the entire frequency band.

Asymmetric UWB aperture antenna with triple band-notched function

In order to avoid the interferences from coexisting systems operating in 3.3-3.6 GHz, 5.15-5.35 GHz, and 5.725-5.825 GHz, an asymmetric triple band-notched antenna suitable for ultra-wideband (UWB) applications is proposed. The printed aperture antenna consists of a circular radiator on one side and a rectangular ground plane with a circular slot on the other side. The asymmetric shape is obtained by moving the radiator away from the center of the structure. The band-notched property is achieved by connecting three quarter-wavelength strips to the circular slot. This design achieves an aperture size of 22 mm by 22 mm, a wide operating frequency range and triple band-notched characteristics. A simple and efficient method of realizing triple band-notched functions in UWB antennas is demonstrated. Compared to the existing designs, the method requires less space for realizing multiple band-notched functions, and can be easily extended to multiple band-notched applications.