1,960,192 research outputs found
Reconfigurable wideband patch antenna for cognitive radio
No full textCognitive radio communication is envisaged to be a new paradigm of methodologies for enhancing the performance of radio communication systems through the efficient utilization of radio spectrum. A key enabler for realization of a cognitive communication system is the capability of re-configurability in the underlying hardware and the associated protocol suite. Reconfigurable double C-Slot microstrip patch antenna fed by 50 ohm microstrip line is proposed in this paper. The frequency tuning is performed by switching on and off two patches. The antenna can operate in dual-band or in very wide band mode in 5, 6 and 7
GHz bands. The wide-band mode can be obtained when both switches are in the ON state with impedance bandwidth of 33.52
% from 4.99 to 7 GHz. The total size of the ground plane is 50 x 50 mm2. The proposed antenna verified through both numerical
simulation and measurement of an experimental prototype. The antenna achieves a gain of 5 to 8 dBi and radiation efficiency
about 80%
Double U-slots patch antenna for tri-band wireless systems
No full textFile shown is the pre-print version of the published paper, with the title "Connected u-slots pathch antenna for WiMAX applications"ABSTRACT: A compact microstrip patch antenna with two U-slots shape is presented.
Detailed simulation and experimental investigation are conducted to understand the behavior
of the two U-slots. The proposed antenna generates three resonant frequencies at 2.7, 3.3, and
5.3 GHz. It can, therefore, be used in Worldwide Interoperability for Microwave Access compliant
communication equipment. The proposed antenna has two U-slot shaped and two
bridge elements to connect both shapes together to adapt the structure to the desired interest
operating frequency. A comprehensive parametric study has been applied to understand the
effect of each U-slot on the antenna’s performance. Moreover, the current distribution for the
three bands is investigated to give further understanding of the antenna behavior. The proposed
antenna is verified experimentally and the simulated and measured results are in good
agreement
Reconfigurable tri-band H-shaped antenna with frequency selectivity feature for compact wireless communication systems
Get PDFThis is the post-print version of the Article. The published version can be accessed from the link below - Copyright @ 2011 IETThis study presents an H-shaped reconfigurable antenna for wireless applications. The antenna consists of an H-shape radiator and a CPW printed on a circuit board and a varactor diode connecting the upper and lower arms of the H-shape radiator for reconfigurability. The uniqueness of the antenna lies on the ability to select the operating mode and frequencies electronically using a varactor diode. By selecting the DC-bias voltages of 11.5, 10 and 8 V across the varactor diode, which in turn selects the corresponding varactor capacitances of 2, 4 and 6 pF, the antenna can be controlled to operate in three different modes, namely a single-band mode to cover the GSM1900, a dual-band mode at 1.88 and 2.4 GHz to cover the GSM1900 and Bluetooth/WLAN, respectively and a tri-band mode at 1.57, 1.88 and 2.4 GHz to cover the GSM1900, WLAN and GPS, respectively. Furthermore, by varying the varactor capacitance from 7 to 13 pF, the GPS and WLAN bands can be tuned by 11.44% (1.57-1.4 GHz) and 6.46% (2.4-2.25 GHz), respectively, yet keeping the 1.88-GHz band unchanged. Detailed studies on the antenna's performance are carried out to investigate the behaviour of the antenna at each resonant frequency in each operating mode.This work is supported by the Measurements for Innovators (MFI) program and the National Measurement Office, an Executive Agency of the Department for Business, Innovation and Skills
Circularly polarized U-Slot antenna
No full textCircularly polarized single-layer U-slot microstrip patch antenna has been proposed. The suggested asymmetrical U-slot can generate the two orthogonal modes for circular polarization without chamfering any corner of the probe-fed square patch microstrip antenna. A parametric study has been carried out to investigate the effects caused by different arm lengths of the U-slot. The thickness of the foam substrate is about 8.5% of the wavelength at the operating frequency. The 3 dB axial ratio bandwidth of the antenna is 4%. Both experimental and theoretical results of the antenna have been presented and discussed
Novel small-size directional antenna for UWB WBAN/WPAN applications
Get PDFThis paper presents a novel small-size directional antenna design for ultrawide-band wireless body area networks/wireless personal area networks applications. The design is based on a typical slot antenna structure with an added reflector in order to achieve directionality. The effects of different antenna parameters and human body proximity on the radiation characteristics are analyzed. Antenna measurements with an optic RF setup were performed in order to characterize the small-size antenna far field radiation pattern. The different structural antenna parameters were optimized via extensive numerical simulations. Results show that for frequencies above 3.5 GHz, where the power front-to-back ratio of the directional antenna is greater than 10 dB, its impedance is nearly the same as in the free space. It is not the case neither for the omnidirectional slot antenna nor the monopole antenna next to the body. Between 3 and 6 GHz performance of the novel directional antenna, in terms of radiation efficiency and SAR values, is significantly improved compared to omnidirectional antenna designs.This paper presents a novel small-size directional antenna design for ultrawide-band wireless body area networks/wireless personal area networks applications. The design is based on a typical slot antenna structure with an added reflector in order to achieve directionality. The effects of different antenna parameters and human body proximity on the radiation characteristics are analyzed. Antenna measurements with an optic RF setup were performed in order to characterize the small-size antenna far field radiation pattern. The different structural antenna parameters were optimized via extensive numerical simulations. Results show that for frequencies above 3.5 GHz, where the power front-to-back ratio of the directional antenna is greater than 10 dB, its impedance is nearly the same as in the free space. It is not the case neither for the omnidirectional slot antenna nor the monopole antenna next to the body. Between 3 and 6 GHz performance of the novel directional antenna, in terms of radiation efficiency and SAR values, is significantly improved compared to omnidirectional antenna designs
A Reconfigurable Ultra-Wideband (UWB) Antenna with Single Band-Rejection
Get PDFIn this paper, a reconfigurable ultra-wideband (UWB) antenna with WLAN band-rejection is presented. The proposed antenna operates in the ultra-wideband frequency band from 2.99 – 10.82 GHz with band- rejection of 5.00 – 5.85 GHz. The structure of the antenna is simple octagon-shaped radiating patch and half ground plane with dimension of 30 x 40 mm2. Bandstop elements (inverted U-shaped slot) are integrated into the structure of the antenna to achieve WLAN bandrejection. Band-rejection reconfigurable capability are achieved by placing RF switches at the slot. By configuring the switch in the ON and OFF modes, two reconfigurable states are realized which are WLAN band-rejection during ON states and full UWB frequency spectrum during off states. The proposed antenna shows a wide impedance bandwidth with sharp rejection at the WLAN band and provide multi-function antenna due to its reconfigurable characteristics. The performance was analyzed in terms of reflection loss, VSWR, gain and radiation pattern. Simulation and measurement result have achieved a good agreement
A reconfigurable wideband and multiband antenna using dual-patch elements for compact wireless devices
Get PDFThis is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2012 IEEEA reconfigurable wideband and multiband C-Slot patch antenna with dual-patch elements is proposed and studied. It occupies a compact volume of 50 × 50 × 1.57 (3925 mm3), including the ground plane. The antenna can operate in two dual-band modes and a wideband mode from 5 to 7 GHz. Two parallel C-Slots on the patch elements are employed to perturb the surface current paths for excitation of the dual-band and the wideband modes. Two switches, implemented using PIN diodes, are placed on the connecting lines of a simple feed network to the patch elements. Dual-band modes are achieved by switching “ON” either one of the two patch elements, while the wideband mode with an impedance bandwidth of 33.52% is obtained by switching “ON” both patch elements. The frequencies in the dual-band modes can be independently controlled using positions and dimensions of the C-Slots without affecting the wideband mode. The advantage of the proposed antenna is that two dual-band operations and one wideband operation can be achieved using the same dimensions. This overcomes the need for increasing the surface area normally incurred when designing wideband patch antennas. Simulation results are validated experimentally through prototypes. The measured radiation patterns and peak gains show stable responses and are in good agreements. Coupling between the two patch elements plays a major role for achieving the wide bandwidth and the effects of mutual coupling between the patch elements are also studied
Beam scanning one-dimensional leaky-wave antenna
No full textAlthough the beam of a leaky-wave antenna (LWA) scans with frequency, steering through the broadside is usually challenging. Various methods have been developed to overcome this limitation. An effective method is using a composite right/left-handed abbreviated as CRLH, structure to design an LWA. In this paper, a CRLH LWA with two different patches is discussed. A rectangular slot is etched on one patch, and the other patch is shorted to the ground with a via at each edge. The radiated beam scans from −46° to +67° when the frequency is swept from 30 to 53 GHz
Wideband blade monopole antenna with sleeved coaxial feed
Get PDFA wideband planar monopole antenna requiring a small ground plane is described. Numerical and measured results confirms the antenna has good radiation efficiency and stable omni-directional radiation patterns over an impedance bandwidth of 4.1:1 covering the 200-850 MHz frequency spectrum
SANTANA- Smart Antenna Terminal Design
No full textThis project is embedded in SANTANA (Smart Antenna Terminal) project. The project goal is to design a Ka-band circularly polarized antenna radiator for the receiver SANTANA system. The research work focuses on two types of circularly polarized antennas: aperture-coupled patch antenna and CPW-fed patch antenna. A two steps design process is used. Firstly, only the antennas and their feed structure are designed and optimized. Secondly, a via-transition to connect to a MMIC layer is added. When designing the aperture-coupled patch antenna, a simplified cavity model method for computation is used to achieve the computational model. Both of the structures are optimized. The aperture-coupled microstrip feed patch antenna is selected to fabricate, so that a transition-VIA is added to the bottom of it. After comparing simulation results and measurement results, the two types of radiators‘s different behavior can be easily observed. Also, the influences of the transition-VIA to the radiator are obviously seen
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