Ultra High Frequency Band Research Articles

Ultrahigh-frequency nano-optomechanical resonators in slot waveguide ring cavities

We demonstrate integrated nano-optomechanical systems with driven flexural resonance up to 760 MHz in the ultrahigh frequency band. The mechanical element of the device is embedded in a slot waveguide racetrack optical resonator with an optical quality factor of 60 000. Displacement sensitivity of 0.45×10−15 m/Hz at 127 MHz is achieved in this circuit cavity configuration.

Low‐profile radio frequency identification tag antenna using a trapezoid patch mountable on metallic surfaces

AbstractA trapezoid patch antenna, designed for ultra high frequency band radio frequency identification tag mountable on metallic surfaces, is presented in this article. The proposed antenna has a simple and low‐profile (0.8 mm thick) structure. The impedance matching can be easily achieved by adjusting the upper‐side width and the height of the trapezoid patch. The reading range of the proposed antenna is verified by calculation and measurement, which shows good agreement. Varying antenna size can provide applicable reading range to suit different applications. The results obtained show that the proposed antenna can work efficiently in free space and on metallic objects. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1697–1700, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25310

Amplitude Shift Keyed Radio Communications for Hostile Environments

This work presents the amplitude modulation radio transmission system for communications in hostile environments. The commissioning of a high temperature oscillator and AM mixer system for the purpose of Amplitude Shift Keyed modulation is presented. While previous work has demonstrated oscillators in the Ultra High Frequency (UHF) band, these have been targeted at applications such as radar and mobile telephones. In this paper we have concentrated on the shortwave bands to maximize the range between a sensor unit and the receiver within wireless networks. The work demonstrates that simple communication systems are already possible for hostile environments and allow for simple sensor data to be wirelessly transmitted to safer working areas.

RFID Regulator Design Insensitive to Supply Voltage Ripple and Temperature Variation

A regulator is designed for radio-frequency identification tags in the ultrahigh-frequency band using the Taiwan Semiconductor Manufacturing Company 0.18-¿m CMOS process. A stable reference voltage with short calibration time is designed by integrating a ripple stabilizer and a temperature stabilizer. The regulator output exhibits a line regulation and load regulation of 12 mV/V and 0.34 mV/mA, respectively, and its power supply rejection ratio is 35.1 dB at 1 MHz.

A wireless vibrating wire sensor node for continuous structural health monitoring

Vibrating wire sensors (VWS) are generally used for strain measurements of structuresin buildings and civil infrastructures. In this paper, a wireless vibrating wiresensor node is developed which can measure resonance frequencies from vibratingwire sensors and can remotely communicate the frequencies by wireless. Thewireless sensor node consists of a sensor module, which excites the vibrating wireand reads the resonance frequencies, a wireless communication module, whichtransmits the wire’s resonance frequencies to the user or administrator, and aprocessor that controls the two modules. The wireless sensor node has the followingcharacteristics: it has multiple channels to enable measurement of multiple vibrating wiresensors (up to four) using a single sensor node; it has a power-saving feature thatenables operation for up to one year; and lastly, the wireless unit uses the 424 MHzUHF (ultra-high frequency) band with good diffraction that has an effect onminimizing the influence of impediments such as structural or nonstructural elements.The wireless sensor node is tested in terms of its measurement precision and itswireless communication performance. As a result, it is confirmed that the nodeenables the long-term structural health monitoring of buildings and infrastructures.

Design and Development of Wireless Communication Transceiver to Support RFID Reader at UHF Band

This paper discusses the design and development of wireless transceiver to support communication between Radio Frequency Identification (RFID) reader and host computer. The transceiver is designed and developed to operate at Ultra High Frequency (UHF) band thus improving the present communication system between the reader and host computer. Presently, RFID reader communicates through wire with host computer. By using wire communication system, the reading and writing range from RFID reader to the transponder is limited, not portable and inconvenient to users. Besides, wire communication between RFID reader and host is not suitable for outdoor applications as farming, animal inventory and property tagging. The proposed wireless communication transceiver is operated at (UHF) band and uses digital amplitude shift keyed (ASK) modulation to modulate the RFID information. The wireless transceiver can fully support, without error, nearly up to 30 meters in line of sight (LOS) and non-line of sight (NLOS). The RF transmitter is connected to the RFID reader, and the RF receiver is connected to the host computer. The scanned RFID data can be read by more than one host computer in real time, thus it is suitable for indoor and outdoor applications, convenient and user friendly.

Near-field antenna for a radio frequency identification shelf in the UHF band

This study presents the design of a near-field reader and tag antenna in the ultra high frequency (UHF) band that can be used for various radio frequency identification (RFID) shelves. The tag antenna is designed by introducing an ‘S’-shaped slot into the circular patch, and the reader antenna is a rectangular slot array fed by microstrip lines. These UHF antennas operating in the near-field are more reliable in many RFID applications where the reading distance is not the major factor. The electric coupling concept between the reader and tag antenna is employed for near-field communication.

Dual-composite right–left-handed transmission lines for the design of compact diplexers

In this study, the use of dual-composite right–left-handed (D-CRLH) transmission lines is proposed for the design of diplexers. The D-CRLH diplexers present advantages over conventional diplexers such as smaller size (especially in the ultra high frequency band). The design procedure and the design equations are presented in this paper. The non-linear phase response of a D-CRLH transmission line has been used to design diplexers at any arbitrary frequencies. Finally, two diplexers have been designed and manufactured: one for quite near frequencies and the other for further ones. The simulation results show good agreement with the measurements. A sensitivity analysis has been provided to show the robustness of this kind of circuits.

Design of a double-layered spiral antenna for radio frequency identification applications

In this study, the authors describe a novel circularly polarised (CP) double-layered spiral antenna (DLSA) consisting of two main spiral radiators printed on a thin substrate, a feed line and a folded ground plane for a ultra-high-frequency (UHF) band radio frequency identification (RFID) reader. The proposed antenna exhibits broad impedance and CP bandwidth characteristics. The fabricated prototype has an axial ratio of less than 3 dB, a return loss of less than –10 dB over an 860–960 MHz range and a gain of 6.7 dB in the operating frequency range. This performance confirms that the proposed antenna is appropriate for commercial RFID use in the UHF band.

LOG PERIODIC FRACTAL KOCH ANTENNA FOR UHF BAND APPLICATIONS

In this paper, the design of Log Periodic Fractal Koch Antennas (LPFKA) is proposed for Ultra High Frequency (UHF) band applications. The procedure to design the LPFKA with three different numbers of iterations in order to reduce the antenna size is discussed. The Computer Simulation Technology (CST) software has been used to analyze the performances of the designed antennas such as return loss, radiation patterns, current distribution and gain. The antennas have been fabricated using FR4 laminate board with wet etching technique. Using fractal Koch technique, the size of the antenna can be reduced up to 27% when the series iteration is applied to the antennas without degrading the overall performances. Both simulated and measured results are compared, analyzed and presented in this paper.

Broadband Capacitively Coupled Patch Antenna for RFID Tag Mountable on Metallic Objects

Design of a capacitively coupled meandered patch antenna is presented in this letter. The antenna is fabricated on a very thin substrate with thickness of 0.8 mm and designed for ultrahigh frequency (UHF) band radio frequency identification (RFID) tag mountable on metallic objects. The capacitively coupled feeding technique is used to perform a broadband operation. Bending a long patch into four half-wavelength radiating elements makes the surface currents of all radiating elements in phase, thus achieving an enhanced antenna gain and a good reading range performance. In addition, the proposed antenna mounted on a metallic platform is studied, and no severe degradation in the reading range is observed .

Low-Profile Meandered Patch Antennas for RFID Tags Mountable on Metallic Objects

This letter presents novel meandered patch antennas that are designed for ultrahigh frequency (UHF) band radio frequency identification (RFID) tags mountable on metallic objects. The antenna has a low-profile structure (0.8 mm thick). Meandering a long patch into several half-wavelength radiating elements makes the surface currents of all radiating elements in phase, thus achieving an enhanced antenna gain and a good reading range performance. In addition, the proposed antennas mounted on a 400 × 400 mm2 metal plate are studied. Little effect of the metal-plate size on the reading range is obtained.

Design of an embedded-feed type microstrip patch antenna for UHF radio frequency identification tag on metallic objects

The design of an embedded-feed type microstrip patch antenna, which can be mounted on metallic objects for radio frequency identification (RFID), is presented. The structure consists of an embedded feed with T-matching networks and a symmetrical radiating rectangular loop patch. The proposed antenna has no shorting plate or via hole and consists of a very thin structure of microstrip patch antenna compared with the conventional metallic tag antennas. The impedance of the presented antenna can be changed to match the impedance values of tag chips by using the T-matching network. The gain radiation pattern performance of the proposed antenna on metal surface is improved so that it can be used for a tag antenna mountable on metal surface in ultra-high frequency (UHF) band RFID applications. The antenna is analysed by full wave simulations, and experimental results are provided for the manufactured prototype.

Performance analysis and test for passive RFID system at UHF band

Performance analysis and test for passive radio frequency identification (RFID) system at ultra high frequency (UHF) band in free space and line-of-sight (LOS) indoor environments are conducted in this article. Performance degradation of different materials is presented, in terms of power received by tag and reader, communication range and link information rates, etc. Particularly, the multipath fading and root mean square (RMS) delay spread in LOS indoor environments are analyzed by a 5-ray model with different polarization, such as horizontal polarization, vertical polarization and circular polarization. A practical test is carried out on an indoor balcony of an office building. In addition, the electric field environment is simulated to analyze multipath degradation using the tool of Ansoft HFSS. According to the test, the recognition rate is almost consistent with the results of theoretical analysis and simulation. The small scale fading and the field nulls are observed. The multipath degradation significantly affects the passive RFID system on communication range and recognition rate, and it is also one of the key limitations on system performance. The variations of power in multipath environments can also influence the information rates, while the rates are still enough for available standard and applications at short range.

UHF Band Ultra-Narrowband Superconducting Filter With Double U-Type Secondary Coupling Structure

A double U-type secondary coupling structure (DUSCS) is used for a compact ultra-narrowband filter in the ultra-high frequency (UHF) band. It can effectively reduce the coupling and thus spacing between coupled twin-spiral resonators. A six-pole superconducting filter at 600 MHz with a fractional bandwidth of 0.083% is designed and fabricated to validate this technique. The filter size is reduced by 15% compared with the filter designed without DUSCSs.

Fabrication of Circular Polarization Antenna on PEI/BSTZ Composite Substrate for the Application of UHF-RFID Reader

The dielectric characteristics of poly(ether imide) (BSTZ) composites are developed. A circular polarization (CP) antenna with a simple structure is designed on a PEI/BSTZ composite substrate for the applications of ultrahigh frequency (UHF) band radio-frequency identification (RFID) readers. Two rectangular stubs on the proposed circular patch of RFID antennas are used to tune the impedance matching effect and to improve the axial ratio performance. The proposed CP antennas are successfully fabricated on the PEI/BSTZ composite substrates, and an antenna with a similar structure is also fabricated on the FR4 substrate for comparison. In this study, we demonstrate that the CP antenna fabricated on the PEI/BSTZ substrate has better characteristics and is smaller than that fabricated on the FR4 substrate. The antenna fabricated on the PEI/BSTZ composite substrate also has a larger impedance bandwidth and a smaller axial ratio than the antennas fabricated on the FR4 substrate.

Detecting characteristics of various type antennas on partial discharge electromagnetic wave radiating through insulating spacer in gas insulated switchgear

A widely used, effective method for diagnosing the insulation of a gas-insulated switchgear (GIS) is to detect partial discharges using signals in the ultrahigh frequency (UHF) band. To detect partial discharge signals that propagate inside a GIS, it is necessary to install a sensor inside or set on the outside of a GIS tank. For GISs that have already been constructed, it is effective to use external diagnosis using electromagnetic wave (EM-wave) signals that radiate (leak) from the insulation spacer of the GIS tank, and there is strong demand for such a diagnosis technology. Externally leaking EM-waves are often detected using an antenna, and multiple antennas supporting different frequency bands are commercially available. The accuracy of external diagnosis could be improved by comparing and evaluating the characteristics of various antennas. The insulation spacer of a GIS tank is usually installed on the flange and fastened with metal bolts. GIS tanks are made electrically continuous by these metal bolts and have the same grounding potential. EM-waves leak from the part of the solid insulator surrounded by these metal bolts and the GIS tanks. This leaking part forms a slot antenna and has a resonant frequency that depends on the spacing between the bolts in the circumferential direction of the flange. At this resonant frequency, the output of externally leaking EM-waves is higher and enables more sensitive measurement. In this study, the detection characteristics with different antenna positions and directions were compared in consideration of the number and positions of the bolts on the spacer, and the frequency characteristics of various antennas were obtained. To improve the detection sensitivity, a prototype of an improved dipole antenna was fabricated and its characteristics were evaluated. Based on the experimental results, an ideal diagnostic system based on the externally leaking EM-waves is proposed.

Fractal Koch dipole antenna for UHF band application

AbstractThe fractal Koch curve is one of the popular fractals shape. This article discussed the analysis of the fractal Koch dipole antenna (FKDA) using log periodic technique. The effect of flare angle of the antenna has been described to reduce the antenna size. The antenna is operated at ultrahigh frequency (UHF) band frequency between 460 MHz and 4 GHz. The analysis is based on the number of elements, degree of flare angle, current distribution, and radiation pattern of the antennas. The antenna has been designed and simulated using computer simulation technology (CST) and fabricated using FR4 board. The performance of the antennas has been measured, analyzed, and discussed in this article. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2612–2614, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24702

Effects of Reader-to-Reader Interference on the UHF RFID Interrogation Range

In this paper, the effects of ultrahigh-frequency band passive radio-frequency identification (RFID) reader-to-reader interference are investigated in terms of the interrogation range. A reader-to-reader interference model based on interference statistics is proposed, and the nominal interrogation range of a desired reader is derived by this model. In order to evaluate the RFID reader-to-reader interference quantitatively, the interrogation-range-reduction ratio (IRRR) is also defined. For a simple case with only one interfering reader, the analytic and experimental results are in good agreement. Reader-reader distance achieving 0% IRRR, indicating no interference between the readers, is 1200 m for the multiple-reader environment. Additionally, IRRR values are calculated in various environments according to the North American and Korean regulations. The maximum number of allowable interfering readers is then calculated by the proposed interference model and a target IRRR.

"Indoor" Protection of Electronic Systems by Means of High-Pass Negative Feedback

An extremely simple first order RC high-pass filter is suggested to suppress harmful radio frequency oscillations, induced by high power electromagnetic pulses. Specifically, a broadband single stage transistor amplifier with a parasitic wiring inductance and also the parasitic junction and mounting capacitances are investigated both numerically and experimentally in the very high and ultrahigh frequency bands.