Zhi-Hong Tu

A Compact Band-Notched UWB Antenna with Controllable Notched Bandwidths by Using Coupled Slots

A compact coplanar waveguide fed (CPW-FED) ultrawideband (UWB) antenna with controllable notched bandwidths for WLAN bands ranging from 5.3 GHz to 5.7 GHz is proposed and implemented. The proposed antenna consists of part of a circular patch and two modified ground planes. Two upper half-wavelength C-shaped slots and another lower half-wavelength C-shaped slot are coupled separately to form a band rejection. The simulation and measurement show that the proposed antenna achieves a well-matched broadband impedance of 3.1–10.6 GHz (|S11| < –10 dB), except the rejection bandwidths of 5.3–5.7 GHz for the centre band of WLAN (|S11| > –5 dB). Moreover, the notched bandwidths can be controlled by adjusting the coupling distances of the corresponding slots. The antenna is successfully designed, simulated and measured with broadband matched impedance and near omnidirectional radiation patterns.

A novel compact single-feed dual-band circular polarization antenna

A new compact single-feed dual-band square-ring patch CP antenna with an unequal cross-slot ground plane is proposed. The size of the new antenna is compact and the simulated results show good performance. Also, it achieves a small frequency ratio.

HIGH-GAIN SLOT ANTENNA WITH PARASITIC PATCH AND WINDOWED METALLIC SUPERSTRATE

In this paper, a directional slot antenna with parasitic patch and windowed superstrate is presented. Through this composition, high-gain property can easily be obtained by this proposed antenna. The proposed antenna has a measured impedance bandwidth of 2.41{2.49GHz for S11 < i10dB, which can cover the 2.4{2.484GHz frequency band of WLAN application. Simulated and measured results show that high-gain features up to 11.50dBi across the corresponding impedance band are achieved. Details of the proposed slot antenna conflgurations and design procedures are given; the experimental results are also given and discussed.

Compact printed dipole antenna with integrated wideband balun for UWB application

A compact UltrawideBand (UWB) dipole antenna with an integrated wideband balun is presented. The proposed antenna consists of a printed dipole, a wideband slot balun embedded in the ground plane, and an inverted L-shaped microstrip feedline. By using the integrated slot balun, the unbalance-to-balance transformer from the microstrip feedline to the dipole antenna is achieved. This antenna achieves a small size of 16 mm× 28 mm × 0.8 mm based on the substrate having a dielectric constant of 2.55, and operates over the frequency band from 2.9 GHz to 10.7 GHz, with the reflection coefficient <;-10 dB and the relative impedance matching bandwidth of 114.7%. The measured results show the nearly omnidirectional radiation pattern over the UWB band.

Differentially T-shape slot antenna with high common-mode suppression for 2.4/5.2/5.8 GHz WLAN MIMO systems

A novel design of a dual-band microstrip slot antenna with high common-mode(CM) suppression for wireless local area network(WLAN) multiple-input-multiple-output (MIMO) systems is proposed in this paper. The proposed MIMO antenna element consists of a T-shape slot and a inverted U-shape microstrip feed line. The T-shape shot includes both open-ended and short-ended slots. Open-ended and short-ended slots are exploited to obtain two resonant modes, whose center frequencies can be adjusted by the slot lengths. The T-shape slot on the top layer is fed by a pair of differential microstrip lines by proximity coupling. Simulated results show that the -10 dB impedance bandwidth of the MIMO antenna covers the 2.4/5.2/5.8 bands for WLAN applications. The measured isolation is better than 15dB for differential-mode(DM) signs in all bands. Besides, the radiation performance is also measured.

CPW-Fed UWB antenna with dual notch-band using embedded slot resonator

A CPW-Fed ultra-wideband antenna with dual notch-band using embedded slot resonator is presented in this paper. Stub-loaded open-loop resonator can be utilized to design compact dual-band bandpass filters with improved out-of-band rejection characteristic. When the stub-loaded open-loop resonator embedded into the feed line of the UWB antenna and transformed into slot resonator, dual notched band property is obtained. By adjusting the parameters of the embedded slot resonator, the dual band-notched UWB antenna can be adopted to minimize the potential interference between the UWB system and the narrow band systems, such as systems in the WiMAX/WLAN bands.

A Novel Microstrip Open-loop Resonator Filter For High Selectivity Application

In this paper, the design of a novel narrowband microstrip filter is presented, the structure is formed by two resonators of different lengths, the length of one resonator is adjusted so that the first odd resonance is tuned to the center frequency, the length of the other resonator is adjusted so that the next even resonance is tuned again to the center frequency, the difference path of the signal in each resonator produces a transmission zero in the insertion-loss response of the filter . The position of the transmission zero can be changed from high rejected band to low rejected band by adjusting the coupling between the ports and resonators. The simulated results validate the new structures for high-selectivity applications.

Triple-band dipole antenna with wideband balun

A triple-band dipole antenna with a wideband balun is proposed, which consists of two dipoles and a bulan. The dipole with two stubs is designed for covering the WLAN bandwidth, another dipole with a stub is designed for covering the WiMAX bandwidth.The size of it is 30mm×25mm, which is based on the substrate having a dielectric constant of 2.55 and the thickness of 0.8mm. The measured return loss has good agreement with the simulated around 2.45/3.5/5.5GHz bands. This antenna would be applied in wireless systems.