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MHz Band (mhz + band)
Selected AbstractsIn-building power lines as high-speed communication channels: channel characterization and a test channel ensembleINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2003Tooraj Esmailian Abstract In-building power lines have often been considered as attractive media for high-speed data transmission, particularly for applications like home networking. In this paper, we develop models for power line channels based both on theoretical considerations and practical measurements. We consider power line channel frequency response and noise models in the 1,30 MHz band and propose a number of power line test channels in which to measure the performance of power line modems. Copyright © 2003 John Wiley & Sons, Ltd. [source] Compact high-gain printed loop-antenna array integrated into a 5-GHz WLAN access pointMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2010Tzi-Chieh Hong Abstract A printed, planar loop-antenna array having a compact structure and high-gain, directional radiation properties for WLAN operation in the 5 GHz band is presented. The antenna-array design is composed of four-folded loops arranged to be of 2 × 2 configuration, printed on both sides of a 1.6-mm thick FR4 substrate, and one system printed circuit board (PCB) serving as an efficient reflector for the loops. The antenna array is set within the boundary of the PCB (size of 50 mm ×65 mm) and stacked there above by a separation distance of 5.4 mm only. That's, the design integrates the system PCB of an access point (AP) into an internal antenna solution for compact outdoor AP applications. The results show that good input matching with voltage standing wave ratio (VSWR) below 1.5 over the 5150,5825 MHz band can be achieved. Directional radiation patterns with peak gain at about 10 dBi were also obtained. Details of the antenna design are described and discussed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2261,2267, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25487 [source] Internal WWAN antenna for the clamshell mobile phone with various chassis shapesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2010Kin-Lu Wong Abstract Stable performances of an internal WWAN antenna applied in the clamshell mobile phone with various chassis shapes are obtained. Six different states including five possible operating states and one closed state (idle condition) of the clamshell mobile phone, wherein the chassis shapes (main ground and upper ground) vary greatly, are studied. The WWAN antenna is mounted at the bottom of the main ground, and there are three connecting positions between the main ground and the upper ground. For each operating states, the upper ground is connected to the main ground at one of the three connecting positions. At each position, a band-stop circuit formed by two parallel LC chip elements is embedded, which is designed to excite a parallel resonance at around 900 MHz and hence leads to very high impedance seen into the upper ground in the 900 MHz band. This greatly decreases the excited surface currents on the upper ground, making the presence of the upper ground to have very small effects on the performances of the WWAN antenna mounted at the bottom of the main ground. At around 1900 MHz, owing to its shorter wavelength, the surface currents on the upper ground excited by the WWAN antenna on the main ground are small. Thus, over both the 900- and 1900-MHz bands, the various orientations of the upper ground to the main ground cause small effects on the WWAN antenna embedded therein. Details of the obtained results are presented. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2148,2154, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25413 [source] Matching a Bluetooth headset antenna on a small system ground by using a conductive wireMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2009Jui-Hung Chou Abstract In this article, a simple, yet effective method for matching a compact planar inverted-F antenna (PIFA) on a small system circuit board for Bluetooth headset applications is presented. The antenna is perpendicular to and extends along the top and right sides of the system ground, making it possible for the antenna to occupy almost no limited board space. Results have shown that by introducing a thin conductive wire soldered to the bottom corner of the system ground, good input matching over the 2400,2484 MHz band can easily be achieved for the PIFA mounted on a small ground of length less than a quarter wavelength at 2440 MHz. Radiation measurements of the proposed design in a real headset attached to a standard head phantom are also taken. Details of the obtained experimental and simulation results are given and discussed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2802,2805, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24755 [source] Compact slot antenna for 2.4 GHz/UWB with dual band-notched characteristicMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2009Feng-Tao Zha Abstract A novel compact microstrip slot antenna for 2.4,2.5 GHz (WLAN) band and ultra-wideband is proposed and fabricated. Two single ring split resonators are etched in the feed line to obtain dual band-notched function in the 5 GHz WLAN band and ITU 8025,8400 MHz band, respectively. The entire antenna only occupies a volume of 33 mm × 35.5 mm × 1 mm. The proposed antenna is analyzed both numerically and experimentally. The measured results and simulated results reach good agreements. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1859,1862, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24475 [source] A high-power Cartesian feedback transmitter including a compact inverted Doherty amplifierMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2008Hanjin Cho Abstract A high-power Cartesian feedback transmitter including a compact inverted Doherty amplifier is presented. The system efficiency was further improved using a bias line adjustment method for the compact inverted Doherty amplifier. After the bias line adjustment from a ,/4 line for the Doherty amplifier, a power-added efficiency (PAE) of 6.9% points was improved from 41.3 to 48.2% at an output power level of 45 dBm. The whole Cartesian feedback transmitter system exhibited an efficiency of 40% and an adjacent channel leakage ratio of-51 dBc at an output power of 45 dBm for 859 MHz band ,/4-DQPSK applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 944,946, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23265 [source] Active integrated antenna for mobile TV signal receptionMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2007Ick-Jae Yoon Abstract This paper proposes a small-sized field-effect transistor (FET) based active integrated antenna (AIA) for terrestrial digital multimedia broadcasting (T-DMB) signal reception, which is one of the mobile TV services allocated to 200 MHz band. The commercially used T-DMB antenna is a 120 mm long monopole, but the size of the proposed one is reduced to 50 mm by the method of active device integration. The active device integrated to the radiator influences not only on the current distribution at the radiator but also the input impedance, results in an antenna size reduction with an enhanced gain. In addition to this, a band-pass filter is designed at the input port of the radiator. This plays a role as a matching circuit between a radiator and an active device as well as provides a band-selection function simultaneously to be free of other high intensity signals existing around the T-DMB band. The antenna effective length related to the same-sized monopole and noise figure are measured to verify the validity of the proposed antenna. The performance of the proposed FET based AIA shows the feasibility of designing absolutely small-sized antenna with active devices integrated compared to an operating frequency band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2998,3001, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22968 [source] Miniaturized microstrip meander-line antenna with very high-permittivity substrate for sensor applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2007Haiwen Liu Abstract This article presents a compact microstrip meander-line antenna for sensor network applications in the 290 MHz band. The antenna is fed by coplanar waveguide and its dimension is 15 mm × 15 mm × 2 mm. Because of the use of a very high relative permittivity substrate (,r = 90) and meander-line structure simultaneously, the side length of the designed antenna is about ,g/12 (,g is the guided wavelength) so that the circuit size is reduced greatly. Measurements verify that the proposed antenna has bandwidth of 12% at the resonant frequency of 293 MHz. Also, the radiation patterns measured at resonance frequencies are very close to omnidirectional in the E-plane. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2438,2440, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22798 [source] Broadband planar DTV antenna in the portable media player held by the user's handsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2007Wei-Yu Li Abstract Effects of the user's hands on the broadband planar DTV antenna in the portable media player (PMP) are studied. The antenna has a wide operating bandwidth covering the 470,806 MHz band for DTV signal reception and a one-layer equivalent simulation hand model including the user's forearm with a relative permittivity of 33.5 and a conductivity of 0.47 S/m is used for the simulation study. Three different conditions of the user's hands (right hand only, left hand only, and both hands) holding the PMP are studied, and their effects on the return loss, radiation efficiency, and radiation patterns of the studied DTV antenna are analyzed. In addition, effects of the user's hands holding the PMP at different positions relative to the studied DTV antenna are analyzed. Results have shown that, for the worst case, the radiation efficiency of the studied DTV antenna is still larger than 60% over the operating band, making the antenna very promising for practical applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1841,1844, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22639 [source] | ||||||||||