Antenna For Mobile Communications Research Articles

Printed internal antenna for mobile broadcasting (DVB-H/T-DMB) and communications (GSM900)

This study proposes a printed internal antenna operating in the digital video broadcasting-handheld (DVB-H) band and the terrestrial digital multimedia broadcasting (T-DMB) L-band for mobile broadcasting and the GSM900 band for mobile communications. Owing to the limited physical size of the mobile terminal, the miniature antenna technique is very important for a low-band application. The proposed antenna consists of a printed rectangular monopole with a U-shaped slot, an extended ground stub and a folder-type chassis, which are easily printed on an FR4 substrate. The antenna occupies an area of only 50×27×mm 2 , which makes it attractive for use with modern multiband and multifunctional slim handsets. The combined behaviour of the antenna resonant mode and the chassis resonant mode is utilised without any matching circuits or magneto-dielectric materials. In addition, the proposed antenna uses a second higher-order resonance of the extended ground stub and the U-shaped slot.

Phased array antenna with crossed dipole antenna for mobile satellite communications

AbstractIn this article, we propose a phased array antenna which uses a crossed dipole antenna with a reflector as an element antenna.The element antenna has conical radiation pattern which is useful for a satellite communication mobile station antenna. The element antenna radiates linearly polarized wave. Both simulation with electromagnetic simulator and experiment are performed in 19‐element array antenna for the beam scanning characteristics. From measured results, the obtained antenna gain is more than 10 dBi from 30° to 60°. It is shown that the characteristics of the array antenna are effective to use for a satellite communications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 2805–2809, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26424

Exposure assessment in front of a multi‐band base station antenna

This study investigates occupational exposure to electromagnetic fields in front of a multi-band base station antenna for mobile communications at 900, 1800, and 2100 MHz. Finite-difference time-domain method was used to first validate the antenna model against measurement results published in the literature and then investigate the specific absorption rate (SAR) in two heterogeneous, anatomically correct human models (Virtual Family male and female) at distances from 10 to 1000 mm. Special attention was given to simultaneous exposure to fields of three different frequencies, their interaction and the additivity of SAR resulting from each frequency. The results show that the highest frequency--2100 MHz--results in the highest spatial-peak SAR averaged over 10 g of tissue, while the whole-body SAR is similar at all three frequencies. At distances > 200 mm from the antenna, the whole-body SAR is a more limiting factor for compliance to exposure guidelines, while at shorter distances the spatial-peak SAR may be more limiting. For the evaluation of combined exposure, a simple summation of spatial-peak SAR maxima at each frequency gives a good estimation for combined exposure, which was also found to depend on the distribution of transmitting power between the different frequency bands.

A numerical coefficient for evaluation of the environmental impact of electromagnetic fields radiated by base stations for mobile communications

The aim of this study is the development of an Electromagnetic Environmental Impact Factor (EEIF). This is a global parameter that represents the level of electromagnetic impact on a specific area due to the presence of radiating systems, such as base station (BS) antennas for mobile communications. The numerical value of the EEIF depends only on the electromagnetic field intensity, a well-defined physical quantity that can easily be measured or computed. The paper describes the significant parameters of the field distribution adopted to evaluate the EEIF, and the assumptions used to develop a proper scale of values. Finally, some examples of application of the EEIF method are analyzed for real situations in a typical urban area.

U-slot Loaded Half Disk Patch Antenna for Mobile Communications

Theoretical investigations of a U-slot loaded half disk patch antenna are presented using equivalent circuit concept. It is found that the antenna shows dual band characteristics with resonant frequency at 4.76 and 6.79 GHz. The dual nature of the antenna is realized by loading shorting pin with U-slot loaded patch. The lower and upper frequency bands are achieved as 443 and 287 MHz respectively. It is noted that the antenna shows frequency ratio of 1.4.

L-strip proximity fed shorted rectangular microstrip antenna for mobile communication

A dual-band L-strip proximity fed shorted rectangular microstrip antenna is proposed and investigated theoretically simulated by HFSS and experimentally. Proposed radiating patch is located about (17.5 mm) above the ground plane. Return Loss and co- and cross polar radiation pattern are presented. Computed and measured results of return loss are in good agreement. The effect of the geometric parameters of the proposed antenna, such as length of the vertical and horizontal portion of the L-strip is also investigated. The impedance bandwidth (−10 dB return loss) 32.5% (calculated) and 33.00% (measured) for the proposed antenna are achieved for optimized antenna design. Significant size reduction (i.e., ∼85%) is obtained as compared with conventional rectangular patch of same resonant frequency. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1567–1571, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25235

Multi-access antenna for an opportunistic radio mobile communication of fourth generation

A new model of two-access reconfigurable antennas for future mobile communication systems is presented in this article. This structure is based on a slot antenna with two separated access ports, isolated and matched at 1 and 2 GHz, respectively. The novelty of this element lies in the fact that first a filtering structure is integrated in the antenna, and then any additional switching or frequency path selecting components that would induce losses and noise degradation is suppressed. Such flexible structures are assumed to be used in a future opportunistic radio, incorporating special features of “spectrum sensing”. The concept of the antenna illustrated by simulation and measurement is presented.

Multiband notebook computer antenna design by FDTD method for GSM/WCDMA system applications

AbstractIn this study, a simple structure designed antenna for 2G and 3G mobile communication applied to notebook computer (NB) is proposed and analyzed by finite difference time domain (FDTD). The proposed antenna has great characteristics of simple structure, easy production, low cost, good impedance matching, and wideband frequency. The antenna main structure is printed on 0.8 mm with permittivity 4.4 FR4 single‐sided PCB, which is bonded to metal bracket. This proposed antenna covers GSM 850/900/1800/1900 and WCDMA multibands and satisfies NB wireless wide area network system. Both FDTD simulation and measurement show that the antenna gain is 2.2 dB for 800 MHz band and 4.6 dB for 1800 MHz band. The 3‐dB passbands are about 136 (824–960 MHz) and 460 MHz (1710–2170 MHz), respectively. The bandwidth of each passband is matched with the desirable values for the NB multiband requirement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2212–2216, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24521

The Analysis of Masts and Towers

For many years both guyed masts and self-supporting towers have been used for supporting antennas for mobile and other communications. The choice between masts and towers has often been determined by the tradition. However masts have its clear advantages in the open country, whereas the towers are more likely to be chosen in the urban areas. Masts and towers are often used for broadcasting of radio and television or antennas for cellular phones. The masts and towers consequently are situated on the top of hills and mountains, where the climate often is extreme with respect to wind load and in some cases due to atmospheric icing. Since the wind is turbulent and the masts and towers are flexible and sensitive to dynamic load, the dynamic response becomes important in the analysis of towers and guyed masts. However there are some differences in the analysis of masts and towers. The wind resistance for lattice sections is dependent on the type of members, the solidity of the sections and for tubular members also dependant on the Reynolds number. Furthermore, latest research within the IASS Working Group for Masts and Towers has shown that the wind resistance of tubular sections is dependent on the turbulence of the wind. The masts act strongly in non-linear fashion since the guy ropes are varying from slackened to a taut string. Over the years different methods have been used for analysing guyed masts making the methods more and more realistic: starting by a gust factor method, over the IASS patch wind method to the Eurocode patch wind method, which gives results close to the results from a stochastic analysis and the time domain analysis. The towers do not act as non-linear as the masts. However, the towers are also sensitive to the dynamics of the wind and a dynamic factor should be applied depending on the turbulence of the wind, the height of the structure etc.

Resource and Performance Evaluations of Fixed Point QRD-RLS Systolic Array through FPGA Implementation

At present, when using space-time processing techniques with multiple antennas for mobile radio communication, real-time weight adaptation is necessary. Due to the progress of integrated circuit technology, dedicated processor implementation with ASIC or FPGA can be employed to implement various wireless applications. This paper presents a resource and performance evaluation of the QRD-RLS systolic array processor based on fixed-point CORDIC algorithm with FPGA. In this paper, to save hardware resources, we propose the shared architecture of a complex CORDIC processor. The required precision of internal calculation, the circuit area for the number of antenna elements and wordlength, and the processing speed will be evaluated. The resource estimation provides a possible processor configuration with a current FPGA on the market. Computer simulations assuming a fading channel will show a fast convergence property with a finite number of training symbols. The proposed architecture has also been implemented and its operation was verified by beamforming evaluation through a radio propagation experiment.

Design of a Quadrifilar Helical Antenna for Satellite and Mobile Communications

Quadrifilar Helical Antenna is one of the most commonly used antenna for satellite and mobile phone systems. It provides a high gain, shaped beam with excellent circular polarization over a wide angular range. The Quadrifilar helix produces a cardioid shaped radiation pattern from a radiator of extremely small size and weight. The antenna provides very high beam width of 128 0 to provide a good coverage of upper hemisphere in vertical plane and omni directional pattern in the horizontal plane.

New Method for Evaluating Height Gain at Subscriber Station for Wireless Access Systems in Microwave Band

This paper presents a model for the variation in height of the subscriber station (SS) antenna with respect to the path loss for microwave-band wireless access systems. The propagation mechanism that causes the dependency of the height variation characteristics of the received level at an SS on the SS location and operating frequency is clarified in terms of geometrical optics (GO) using the uniform geometrical theory of diffraction (UTD). The height variation characteristics strongly depend on whether or not regular reflected waves that have a higher level than that of the diffracted wave arrive at the SS. A representation of the model is shown. The model is validated using measured data at 2.2, 5.2, and 25.15 GHz and the validity of the model is shown. This model is useful in the radio zone design of microwave-band broadband wireless access (BWA) systems operating in a non-line-of-sight environment, and in estimating the height gain at a mobile station antenna for mobile communications.

On Analysis of Planar Antennas Using FDTD Method

The FDTD method is a powerful method for analysis of electromagnetic flelds in microwave circuits and devices, antennas, optical devices and transmission lines. In this paper, numerical conditions in analysis of planar antennas using the FDTD method are considered and found for a planar dipole antenna. The obtained results are compared with other and experimental results. DOI: 10.2529/PIERS061002234141 The planar antennas that are useful for mobile communications have been developed for many researchers. The FDTD method is a powerful method for analysis of planar antennas that are deflned as antennas that have planar shapes. We have analyzed several kinds of planar antennas for mobile communications. In this paper, numerical conditions in analysis of planar antennas using the FDTD method (3) are considered and found for a planar dipole antenna. In order to use the method, it is important to decide the number of layers of the PML and the distance between the antenna and the wall of the analytical area. If they are decided appropriately, the computational time and memories are saved. Therefore, the relation between them is discussed precisely. The FDTD method which used their numerical values are applied to several planar antennas (1,2). The obtained results are compared with other and experimental results. 2. FDTD METHOD

Three-band Modified Transmission Line Antennas for Mobile Communication

Three-band Modified Transmission Line Antennas for Mobile Communication

Switched Beam Array Antenna for Sectorized Optimum Power Distribution into Discrete Localities of Rural Area

The technology of Switched Beam Array Antenna for mobile communications has received enormous interest worldwide in recent decade. This type of smart antenna (another type is Adaptive Array Antenna) forms a pattern that adapts to the current radio conditions improving the communication link. The principal reason for applying Switched Beam Array Antenna is the possibility for a large increase in capacity and to introduce new services. The purpose of this paper is to give a performance analysis of Switch Beam Smart Antenna (SBSA) using micro strip patch elements with simulation results obtained by using CST Microwave StudioTM, in KCSTC of IIT Kharagpur.

Design of a Wide-Band L-Probe Patch Antenna for Pattern Reconfiguration or Diversity Applications

By supporting an L-probe coupled circular patch antenna with four metallic posts at appropriate locations, it is demonstrated that the conical and the broadside modes which are excited separately by two different sets of L-shaped probes, can be operated at the same frequency range. For a tested antenna operated at 1.85 GHz, the bandwidth (SWR<2) achieved is 24%, and the isolation between the two input ports is 28 dB. The gains of the conical and broadside modes are 4 and 8.5 dBi, respectively. With suitable switching feed networks, the antenna can be reconfigurable in radiation pattern. The antenna can also be used as a pattern diversity antenna for modern mobile communications.

Circularly polarised equilateral triangular patch array antenna for mobile satellite communications

A satellite-tracking left-handed circularly polarised triangular-patch array antenna has been developed to support the next generation of mobile satellite communications using Japanese Engineering Test Satellite VIII. The targeted minimum gain of the antenna was set to 5 dBic at an elevation of 48° in the Tokyo area, for applications of about a hundred kbit/s data transfer. The antenna is composed of three equilateral triangular patches and fed by a dual-proximity feed. The influence of the array configuration on the characteristic of this antenna is investigated using a method of moments (MoM) approach and a simple point source model. The measurement of the fabricated antenna was then performed to confirm the simulation results. The result showed that the 10 mm distance between the patch apex to the centre of the array antenna satisfies the target. The frequency characteristic of the fabricated antenna is 0.7% shifted to the higher frequency, and the maximum gain is 0.9 dB lower than the simulation results. The result also shows that the characteristic of the patch array antenna satisfies the specification at elevation angle El=48°, especially the 5 dBic gain coverage of the results covers the whole azimuth angle in a conical-cut plane at El=48°.

Circularly polarised equilateral triangular patch antenna for mobile satellite communications

A left-handed circularly polarised (LHCP) triangular patch antenna is developed to support the next generation of mobile satellite communications using Engineering Test Satellite VIII (ETS-VIII). The targeted minimum gain of the antenna is set to 5 dBic for applications of a hundred kbps data transfer with an axial ratio less than 3 dB for circular polarisation. A dual-proximity-coupled equilateral triangular patch antenna is proposed and simulated by the method of moments (MoM) for finite and infinite ground plane models to investigate the ground plane effect. Then measurements of the fabricated antenna are performed to confirm the simulation results. The measurement results show that the frequency characteristics of the fabricated antenna is 0.2% shifted to the higher frequency, and the maximum gain is 0.45 dB lower than the result of the finite ground plane model. Additionally, the simulation results show the ground plane size influences the antenna characteristics, especially the gain and axial ratio of the developed antenna.

Polygonal Patch Antennas with Reactive Impedance Surfaces

Here we present an innovative design of microstrip antennas for wide-band mobile communications. In order to obtain reduced back-radiation, while keeping the overall antenna dimensions suitably compact for practical terminals, the proposed radiators are backed by a reactive ground plane, constituted of a suitably designed pattern of metallic patches. Moreover, the operative bandwidth is increased with the use of a proximity coupling feed and the choice of a polygonal patch shape. Some numerical results are reported, obtained through a rigorous Method of Moment numerical tool, to show the effective improvement that this design may offer in the antenna performance for UMTS mobile communication systems.

Wideband patch antennas for mobile communications

This paper describes a new technique for bandwidth enhancement of microstrip patch antennas. An electromagnetically coupled (EMC) feeding structure was employed to increase the bandwidth. L-strip feeding rectangular and triangular patches were simulated and tested. The obtained bandwidth ( SWR ⩽ 2 ) is about 1200 MHz (52%) for the rectangular patch, while that of the triangular one is around 1300 MHz (56%). These results provide evidence that the proposed designs can be used in the DCS, PCS, UMTS, WLAN and IMT-2000 service frequency bands.