Showing papers on "Coaxial antenna published in 2008"

A Compact Ultrawideband Antenna With 3.4/5.5 GHz Dual Band-Notched Characteristics

Abstract: We propose a compact planar ultrawideband (UWB) antenna with 3.4/5.5 GHz dual band-notched characteristics. The antenna consists of a beveled rectangular metal patch and a 50 Omega coplanar waveguide (CPW) transmission line. By etching two nested C-shaped slots in the patch, band-rejected filtering properties in the WiMAX/WLAN bands are achieved. The proposed antenna is successfully simulated, designed, and measured showing broadband matched impedance, stable radiation patterns and constant gain. An equivalent circuit model of the proposed antenna is presented to discuss the mechanism of the dual band-notched UWB antenna. A UWB antenna and a single band-notched one are also provided for references.

Planar Slot Antenna Backed by Substrate Integrated Waveguide Cavity

Abstract: A novel design method of low profile cavity backed planar slot antenna has been described in this paper. The whole antenna including backed cavity and feeding element is completely constructed at a single substrate by using substrate integrated waveguide technique and grounded coplanar waveguide. An example with 1.7% bandwidth has been presented, which has 5.4 dBi gain, 16.1 dB front-to-back ratio and -19 dB maximum cross polarized radiation level with its total thickness less than lambda0/50. The proposed antenna keeps good radiation performance of conventional cavity backed antenna and has advantages of conventional planar antenna including low profile, light weight, easy fabrication with low cost and convenient integration with planar circuit.

Design and Evaluation of a Reconfigurable Antenna Array for MIMO Systems

Abstract: New reconfigurable antenna array is demonstrated for multiple input multiple output (MIMO) communication systems that improves link capacity in closely spaced antenna arrays. The antenna system consists of an array of two printed dipoles separated by a distance of a quarter wavelength. Each of the dipoles can be reconfigured in length using PIN diode switches. The switch configuration can be modified in a manner adaptive to changes in the environment. The configuration of switches effects the mutual coupling between the array elements, and subsequently, the radiation pattern of each antenna, leading to different degrees of pattern diversity which can be used to improve link capacity. The PIN diode-based reconfigurable antenna solution is first motivated through a capacity analysis of the antenna in a clustered MIMO channel model. A new definition of spatial correlation coefficient is introduced to include the effects of antenna mismatch and radiation efficiency when quantifying the benefit of pattern diversity. Next, the widespread applicability of the proposed technique is demonstrated, relative to conventional half wavelength printed dipoles, using computational electromagnetic simulation in an outdoor and indoor environment and field measurements in an indoor laboratory environment. It is shown for the 2 times 2 system considered in this paper, that an average improvement of 10% and 8% is achieved in link capacity for a signal to noise ratio (SNR) respectively of 10 dB and 20 dB in an indoor environment compared to a system employing non reconfigurable antenna arrays.

Multimode antenna structure

Abstract: One or more embodiments are directed to a multimode antenna structure for transmitting and receiving electromagnetic signals in a communications device. The communications device includes circuitry for processing signals communicated to and from the antenna structure. The antenna structure is configured for optimal operation in a given frequency range. The antenna structure includes a plurality of antenna ports operatively coupled to the circuitry, and a plurality of antenna elements, each operatively coupled to a different one of the antenna ports. Each of the plurality of antenna elements is configured to have an electrical length selected to provide optimal operation within the given frequency range. The antenna structure also includes one or more connecting elements electrically connecting the antenna elements such that electrical currents on one antenna element flow to a connected neighboring antenna element and generally bypass the antenna port coupled to the neighboring antenna element. The electrical currents flowing through the one antenna element and the neighboring antenna element are generally equal in magnitude, such that an antenna mode excited by one antenna port is generally electrically isolated from a mode excited by another antenna port at a given desired signal frequency range without the use of a decoupling network connected to the antenna ports, and the antenna structure generates diverse antenna patterns.

Frequency Reconfigurable U-Slot Microstrip Patch Antenna

Abstract: A frequency reconfigurable microstrip patch antenna is presented. It is found that the incorporation of a U-slot in the patch can provide a flat input resistance and a linear input reactance across a wider bandwidth than the conventional patch antenna. By placing a variable capacitor and an inductor at the antenna input, the impedance matching frequency of the antenna can be varied. The fabricated prototype antenna attains a tunable frequency range from 2.6 to 3.35 GHz. The proposed antenna is simple in structure, and the control circuitry is placed underneath the ground plane. It is suitable for use in reducing the crosstalk from adjacent channels in multichannel system.

Design of compact vivaldi antenna arrays for uwb see through wall applications

Abstract: Two different types of Vivaldi antenna arrays have been designed for UWB see through wall applications. The first is a 16 × 1 antipodal Vivaldi antenna covering 8-12 GHz, and the second is an 8×1 tapered slot antenna for 2-4 GHz frequency range. The array elements are optimized to have a compact size and almost constant gain with frequency. Wilkinson power dividers were designed and fabricated to compose the feed network for the Vivaldi antenna arrays. Measured results of the manufactured antipodal and tapered slot Vivaldi antenna arrays are in excellent agreement with the simulated ones, with a gain of more than 13dBi and 12 dBi respectively within their respective operating band. The first array is geared towards see through dry wall with high resolution, while the second is designed at lower frequencies to allow see through concrete wall applications. Full arrays were manufactured and connected to multi-throw switches and have been utilized as part of synthetic aperture radar.

A Low-Cost 60-GHz Switched-Beam Patch Antenna Array With Butler Matrix Network

Abstract: In this letter, a low-cost 60-GHz switched-beam patch antenna array with Butler matrix network is developed and experimentally demonstrated. In order to improve integration with the patch elements, a 4 times 4 planar Butler matrix is implemented in a low-dielectric substrate. The four rectangular patches fed by inset microstrip lines are connected to the outputs of the Butler matrix for the 60-GHz operation. Because of the fabrication tolerances, the operating frequency of the fabricated antenna shifts to 62 GHz. The radiation patterns measured at 62 GHz are in good agreement with the theoretical array factors. The antenna developed in this letter provides a cost-effective approach to implement an adaptive antenna for 60-GHz wireless communications.

Antenna configurations for compact device wireless communication

Abstract: A diversity antenna for use with a portable host device such as a laptop computer, for example as part of a PCMCIA card pluggable into the laptop computer to enable wireless computer by the laptop computer, includes a main antenna and a diversity antenna. Various configurations for these antennas are possible, including the use of a balanced dipole as the main antenna element and a split diversity antenna for the diversity antenna element. The diversity antenna provides high isolation between the antenna elements and isolation from interfering self-noise generated by the host device.

Half-Mode Substrate Integrated Waveguide (HMSIW) Leaky-Wave Antenna for Millimeter-Wave Applications

Abstract: A novel leaky-wave antenna is demonstrated and developed at Ka-band in this work based on the newly proposed half-mode substrate integrated waveguide (HWSIW). This antenna is accurately simulated by using a full-wave electromagnetic simulator and then fabricated through a single-layer printed circuit board (PCB) process. Wide bandwidth and a quasi-omnidirectional radiation pattern are obtained. The proposed antenna is therefore a good candidate for millimeter-wave applications. Measured results are in good agreement with simulated results.

A 60-GHz Millimeter-Wave CPW-Fed Yagi Antenna Fabricated by Using 0.18- $\mu\hbox{m}$ CMOS Technology

Abstract: This letter presents a 60-GHz millimeter-wave on-chip Yagi antenna fabricated with a 0.18-mum CMOS process. A feeding network is designed in a coplanar waveguide (CPW) technology. The 0.18-mum six-metal-layer CMOS process allows the on-chip antenna to utilize a simple CPW-to-coplanar-stripline feed transition and the first metal layer to implement a reflector strip. The CMOS antenna chip size is 1.1 x 0.95 mm2 . A FEM-based 3D full-wave electromagnetic solver, the HFSS, is used for design simulation. The measured antenna input VSWR is less than two from 55 to 65 GHz. The front-to-back ratio of the Yagi antenna is about 9 dB. The measured maximum antenna power gain is about -10 dBi. The simulated antenna radiation efficiency is about 10%.

A novel uwb elliptical slot antenna with band-notched characteristics

Abstract: This paper presents a novel band-notched elliptical slot antenna for Ultra Wide-Band (UWB) communication, which is printed on a dielectric substrate of RT/duroid 6006 with relative permittivity (er) of 6.0, thickness of 1.27 mm, and fed by an elliptical open ended microstrip line connected to the 50 Ω main line. This antenna is designed to be used in frequency band of 3.1–10.6 GHz. Bandnotched characteristics of antenna to reject the frequency band of 5.15–5.825GHz, which is limited by IEEE 802.11a, is realized by parasitic inverted-U strip attached to the elliptical slot plane. Effects of varying the parameters of parasitic inverted-U strip on performance of proposed antenna have been investigated. The antenna with optimal parameters obtained from parametric study is fabricated and measured. It is observed that the simulation and experimental results have good agreements with each other. 128 Fallahi, Kalteh, and Golparvar Roozbahani

A Reconfigurable High-Gain Partially Reflecting Surface Antenna

Abstract: A high-gain partially reflective surface (PRS) antenna with a reconfigurable operating frequency is presented. The operating frequency is electronically tuned by incorporating an array of phase agile reflection cells on a thin substrate above the ground plane of the resonator antenna, where the reflection phase of each cell is controlled by the bias voltage applied to a pair of varactor diodes. The new configuration enables continuous tuning of the antenna from 5.2 GHz to 5.95 GHz using commercially available varactor diodes, thus covering frequencies typically used for WLAN applications. Both the PRS and phase agile cell are analyzed, and theoretical and measured results for gain, tuning range, and radiation patterns of the reconfigurable antenna are described. The effect of the varactor diode series resistance on the performance of the antenna is also reported.

Wideband Circularly Polarized Antenna With L-Shaped Slot

Abstract: A wideband circularly polarized (CP) L-slot antenna single fed by L-shaped feed line is designed. Wideband CP is obtained by truncating one of the corners of the antenna element. This arrangement introduces orthogonal components with quadrature phase difference to excite circularly polarized wave. A bandwidth of 46.5% (2.18-3.5 GHz) is achieved with an dB and dB. Good agreement between measured and computed results is achieved. Moreover, parametric study results are presented.

Dual staggered vertically polarized variable azimuth beamwidth antenna for wireless network

Abstract: An antenna system for wireless networks having a dual stagger antenna array architecture is disclosed. The antenna array contains a number of driven radiator elements that are spatially arranged in two vertically aligned groups each having pivoting actuators so as to provide a controlled variation of the antenna array's azimuth radiation pattern.

Partitioned aperture array antenna

Abstract: A partitioned aperture array antenna. The novel antenna includes a first subarray having a first number of antenna elements equipped with transmit functionality and a second subarray having a second number of antenna elements equipped with receive functionality, wherein the first and second numbers are not equal and the first and second subarrays have at least one common antenna element. In an illustrative embodiment, the first subarray includes a transmit circuit coupled to each antenna element in the first subarray for controlling a relative transmit phase of the antenna element to steer an overall antenna transmit beam, and the second subarray includes a receive circuit coupled to each antenna element in the second subarray for controlling a relative receive phase of the antenna element to steer an overall antenna receive beam.

Antenna for a level meter employing the radar principle

Abstract: In an antenna for a level meter employing the radar principle, a fastening device is provided for detachably mounting a dielectric insert in the antenna. The fastening device may be a continuous clamping collar that clamps the dielectric insert in place in the antenna. This offers a simple, universally employable possibility for fastening a dielectric insert in the antenna.

CPW-Fed Koch Fractal Slot Antenna for WLAN/WiMAX Applications

Abstract: A dual wide-band CPW-fed modified Koch fractal printed slot antenna, suitable for WLAN and WiMAX operations, is proposed in this paper. Here, the operating frequency of a triangular slot antenna is lowered by the Koch iteration technique resulting in a compact antenna. Studies on the impedance and radiation characteristics of the proposed antenna indicate that a modified Koch fractal slot antenna has an impedance bandwidth from 2.38 to 3.95 GHz and 4.95-6.05 GHz covering 2.4/5.2/5.8 GHz WLAN bands and the 2.5/3.5/5.5 GHz WiMAX bands. The antenna exhibits omnidirectional radiation coverage with a gain better than 2.0 dBi in the entire operating band. Empirical relations are deduced and compared with the results.

A Compact Multiband Monopole Antenna With a Defected Ground Plane

Abstract: A compact multiband antenna is proposed that consists of a printed circular disc monopole antenna with an L-shaped slot cut out of the ground, forming a defected ground plane. Analysis of the current distribution on the antenna reveals that at low frequencies the addition of the slot creates two orthogonal current paths, which are responsible for two additional resonances in the response of the antenna. By virtue of the orthogonality of these modes the antenna exhibits orthogonal pattern diversity, while enabling the adjacent resonances to be merged, forming a wideband low-frequency response and maintaining the inherent wideband high-frequency response of the monopole. The antenna exhibits a measured -10 dB S 11 bandwidth of 600 MHz from 2.68 to 3.28 GHz, and a bandwidth of 4.84 GHz from 4.74 to 9.58 GHz, while the total size of the antenna is only 24 times 28.3 mm. The efficiency is measured using a modified Wheeler cap method and is verified using the gain comparison method to be approximately 90% at both 2.7 and 5.5 GHz.

A Printed Monopole Antenna With Two Steps and a Circular Slot for UWB Applications

Abstract: This letter presents a printed monopole antenna with two steps and a circular slot for ultrawide band (UWB) applications. The proposed antenna is fabricated and tested. The proposed antenna has a wide frequency bandwidth of 8.4 GHz starting from 3 GHz up to 11.4 GHz for a return loss (S_11) of less than - 10dB and gain flatness over the frequency range. Measured results show also that the proposed antenna features satisfactory radiation characteristics within the achieved impedance bandwidth. By introducing a simple and proper narrow slot in the radiating element, frequency-notched characteristics can be obtained and a good band-notched performance in the 56 GHz band can be achieved.

Single-Fed Microstrip Patch Antenna With Switchable Polarization

Abstract: 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.

Dual band antenna and methods for use therewith

Abstract: A dual band antenna includes a far field antenna structure for facilitating the communication of first data with a remote device via far field signaling in a millimeter wave band. A near field antenna structure facilitates the communication of second data with a remote device via near field signaling in a near field band. The far field antenna structure and the near field antenna structure share at least one common antenna element.

CPW-Fed Multi-Band Omni-Directional Planar Microstrip Antenna Using Composite Metamaterial Resonators for Wireless Communications

Abstract: A novel approach for the design of a compact multiband planar microstrip antenna is presented. This type of antenna is composed of composite metamaterial resonators (including conditional microstrip resonators and metamaterial resonators), and fed by signal feed. A sample antenna with composite closed-ring resonator and split-ring resonator (SRR) fed by 50 Ω coplanar waveguide (CPW) developed on FR4 epoxy substrate for multi-band wireless communication applications is presented. Appropriate design of the composite structure resulted in three discontinuous resonant bands. The fundamental magnetic resonant and electric resonant frequency of SRR and the first electric resonant frequency of the closed-ring resonator were combined to form low, middle, and high resonant band. The properties of this antenna are investigated by theoretical analysis and finite element method (FEM) simulations. The numerical results show that the proposed antenna has good impedance bandwidth and radiation characteristics in the three operating bands which cover the required band widths of the 2.4/5.2/5.8GHz wireless local-area networks (WLAN) and 3.5/5.5 GHz worldwide interoperability for microwave access (WiMax) with return loss of better than 10 dB. The antenna also has stably omni-directional H-plane radiation patterns within the three operating bands.

3.5/5.5 Ghz dual band-notch ultra-wideband antenna

Abstract: A compact and simple design of a CPW-fed planar antenna for ultra- wideband application with dual band-notch characteristics is presented. The proposed antenna yields an impedance bandwidth of 3.1- 10.6 GHz with VSWR < 2, except the bandwidths of 3.3-3.9 GHz for WiMAX and 5-6 GHz for WLAN. The antenna is successfully simulated, designed, and measured, showing broadband matched impedance, stable gain and omnidirectional radiation patterns.

Hybrid antennas for electronic devices

Abstract: A portable electronic device is provided that has a hybrid antenna. The hybrid antenna may include a slot antenna structure and an inverted-F antenna structure. The slot antenna portion of the hybrid antenna may be used to provide antenna coverage in a first communications band and the inverted-F antenna portion of the hybrid antenna may be used to provide antenna coverage in a second communications band. The second communications band need not be harmonically related to the first communications band. The electronic device may be formed from two portions. One portion may contain conductive structures that define the shape of the antenna slot. One or more dielectric-filled gaps in the slot may be bridged using conductive structures on another portion of the electronic device. A conductive trim member may be inserted into an antenna slot to trim the resonant frequency of the slot antenna portion of the hybrid antenna.

Compact Dual-Band Slot Antenna for 2.4/5ghz WLAN Applications

Abstract: This paper presents a compact dual-band slot antenna for 2.4/5 GHz WLAN applications. The radiating elements of the proposed antenna are composed of a square ring slot and a circular ring slot, operating at 2.4 GHz and 5 GHz bands respectively. The antenna size is very compact (40 mm × 40 mm × 1 mm), and can be integrated easily with other RF front-end circuits. It is demonstrated that the proposed antenna can completely cover the required bandwidths of IEEE 802.11b/g (2.4–2.485 GHz) and IEEE 802.11a (5.15–5.825 GHz) with satisfactory radiation characteristics. Good agreement is achieved between the simulated and measured results.

A Novel Series-Fed Taper Antenna Array Design

Abstract: To improve the performance of microstrip antenna array, a matching-in-step (MIS) configuration of microstrip series-fed taper array is designed. Compared to the traditional one, the novel antenna array has a better VSWR characteristic. The design procedure of the MIS antenna array is discussed in detail, and some valuable results are acquired. Numerical results are obtained and a very good agreement is observed between experimental and simulated results of such arrays.

Printed Wide-Slot Antenna for Wideband Applications

Abstract: The design and analysis of a novel printed wide-slot antenna, fed by a microstrip line, for wideband communication systems is presented. Detailed simulation and experimental investigations are conducted to understand its behavior and optimize for broadband operation. The designed antenna has a wide operating bandwidth of over 120% (2.8-11.4 GHz) for S11 <-10 dB. In addition to being small in size, the antenna exhibits stable far-field radiation characteristics in the entire operating bandwidth, relatively high gain, and low cross polarization. By properly choosing the suitable slot shape, selecting similar feed shape and tuning their dimensions, the design with very wide operating bandwidth, relatively small size and improved radiation pattern is obtained. A comprehensive parametric study has been carried out to understand the effects of various dimensional parameters and to optimize the performance of the designed antenna. Results show that the impedance matching of this kind of antenna is greatly affected by the feed-slot combination and feed gap width, with the slot shape being a main contributor of the radiation characteristics. The simulated and measured Results for return loss, far-field E and H-plane radiation patterns, and gain of designed antenna are presented and discussed.

A practical miniaturized u-slot patch antenna with enhanced bandwidth

Abstract: In this paper, an asymmetric U-slot patch antenna with low probe diameter is presented. It will be shown that reduction in probe diameter causes in reduction in bandwidth. One of the characteristics of this antenna is keeping the bandwidth in 30% in spite of reduction in antenna size and use of low probe diameter compared to antenna presented in (1). The presented antenna in this paper has been fabricated by pcb technique and tested. The far-field results have also been presented based on simulation and measurement. Although the antenna has high cross polarisation level, in the case of using circular polarisation, the use of this antenna can be recommended because of its reduced size, high impedance bandwidth, high total gain in spite of having low size, and ease of fabrication.

Substrate integrated waveguide antenna array

Abstract: A substrate integrated waveguide (SIW) slot full-array antenna fabricated employing printed circuit board technology. The SIW slot full-array antenna using either single or multi-layer structures greatly reduces the overall height and physical steering requirements of a mobile antenna when compared to a conventional metallic waveguide slot array antenna. The SIW slot full-array antenna is fabricated using a low-loss dielectric substrate with top and bottom metal plating. An array of radiating cross-slots is etched in to the top plating to produce circular polarization at a selected tilt-angle. Lines of spaced-apart, metal-lined vias form the sidewalls of the waveguides and feeding network. In multi-layer structures, the adjoining layers are coupled by transverse slots at the interface of the two layers.

Band-Rejected Design of the Printed Open Slot Antenna for WLAN/WiMAX Operation

Abstract: The band-rejected designs of the printed open slot antenna for wireless local area network (WLAN)/worldwide interoperability for microwave access (WiMAX) applications are investigated. First, the broadband characteristic (2.3 ~ 6uarr GHz) of open slot antenna design with small size is implemented and measured. Then, inserted a single strip on the broadband antenna is studied and investigated. By inserting a strip on the printed open slot of the broadband antenna, to reject frequency from 3.56 to 4.58 GHz, a dual-broadband design of the open slot antenna with small size is obtained for WLAN applications in the 2.4 GHz (2400-2484 MHz) and 5 GHz (5150-5825 MHz) bands. Furthermore, by inserting two strips of different length on the open slot antenna, a three-band antenna is achieved. By adjusting the dimension of two strips on open slot antenna, a three operating modal frequencies at 2.37 ~ 2.72,3.31 ~ 3.78, and 4.5 ~ 5.97 GHz for WiMAX application have been obtained. Detailed design steps and experimental results for the designs are studied and investigated in this paper.