Showing papers on "Feed line published in 2011"

Compact Disc Monopole Antennas for Current and Future Ultrawideband (UWB) Applications

Abstract: Circular disc monopole antennas are investigated for current and future ultrawideband (UWB) applications. The studied antennas are compact and of small size (25 mm × 35 mm × 0.83 mm) with a 50-Ω feed line and offer a very simple geometry suitable for low cost fabrication and straightforward printed circuit board integration. More specifically, the impedance matching of the classic printed circular disc UWB monopole is improved by introducing transitions between the microstrip feed line and the printed disc. Two particular designs are examined using a dual and single microstrip transition. By using this simple antenna matching technique, respective impedance bandwidths (|Sn | <; -10 dB) from 2.5 to 11.7 GHz and 3.5 to 31.9 GHz are obtained. Results are also compared to a classic UWB monopole with no such matching network transitions. Measured and simulated reflection coefficient curves are provided along with beam patterns, gain and group delay values as a function of frequency. The transient behavior of the studied antennas is also examined in the time domain.

Circular microstrip slot antenna for dual- frequency rfid application

Abstract: A compact wideband dual-frequency microstrip antenna is proposed in this paper. By employing an ofiset microstrip-fed line and a strip close to the radiating edges in the circular slot patch, an antenna operating at dual frequency with the impedance bandwidth of 26.2% and 22.2% respectively is presented. By attaching a strip to the radiating edges opposite to the microstrip-fed line, this alters the current distribution and radiation on the antenna at the second resonant frequency. The second frequency is also tunable by varying the lengths of the microstrip-fed line. It is demonstrated that the proposed antenna covers the widebands of UHF and microwave for RFID application. A good agreement is obtained between the simulated and experimental results.

A CPW-Fed Broadband Circularly Polarized Regular-Hexagonal Slot Antenna With L-Shape Monopole

Abstract: A regular-hexagonal structure of wide-slot antenna for broadband circular polarization (CP) based on coplanar waveguide (CPW) feed is presented. By protruding into the slot an L-shape monopole patch, and featuring two inverted-L grounded strips around two opposite sides of the slot, wide impedance bandwidth and wide axial-ratio (AR) bandwidth can be obtained simultaneously. By notching a rectangle in the ground conductor near the feed line, the antenna performance is further improved. The proposed antenna can provide an impedance bandwidth (S11 <; -10 dB) of 86% and a 3-dB AR bandwidth of 50%, respectively.

Broadband CPW-Fed Circularly Polarized Square Slot Antenna With Three Inverted-L-Shape Grounded Strips

Abstract: A new form CPW-fed broadband circularly polarized square slot antenna (CPSSA) with three inverted-L-shape grounded strips around the corners of the slot is proposed and fabricated. In comparison to the previous CPSSA structures, the axial-ratio (AR) bandwidth of the antenna is increased, which is two times wider than the previous proposed design. By embedding the L-shape strip to the ground plane and using the vertical stub to the feed line, very good axial-ratio bandwidth is obtained. The measured impedance bandwidth and AR of the realized CPSS antenna with optimized parameters is from 2 to 7 GHz (3.5:1, 110%) for VSWR ≤ 2 and 2-5 GHz (2.5:1; 85%) for AR ≤ 3 dB respectively. Throughout this letter, the improvement process of the AR and S11 properties is completely presented and discussed.

Wideband RFID Tag Antenna for Metallic Surfaces Using Proximity-Coupled Feed

Abstract: A low-cost, wideband patch antenna for radio frequency identification tags mountable on metallic surfaces is presented. A novel proximity-coupled feed structure, in which the direction of the microstrip feed line is parallel to that of the resonant length of the radiating patch and one end of the feed line is shorted to the ground, is proposed to perform simple and wideband impedance matching between the antenna and tag chip without any additional matching networks. The proposed design is verified by simulation and measurement. The measured 3-dB return-loss bandwidth is about 49 MHz, which totally covers the 26-MHz bandwidth requirement in North America. The measured read range is about 8.9 m when the tag antenna is mounted on a metal plate with a size of 200 × 200 mm2.

Novel Dual-Mode Balun Bandpass Filters Using Single Cross-Slotted Patch Resonator

Abstract: In this letter, a novel dual-mode bandpass balun filter is presented using a miniaturized cross-slotted patch resonator. This balun filter consists of a single slit-loaded patch etched by a pair of cross slots and a stepped-impedance open stub. An unbalanced input port is orthogonally arranged in-between two balanced output ports along the patch, and each feed line is connected to an additional stub for enhanced coupling. Due to the dual-mode characteristic of the patch resonator, two transmission poles can be easily constructed at both balanced passbands. Asymmetrical width and length of the cross-loaded slots perturb the field of the patch and excite two degenerate modes simultaneously, while the attached open-circuited stub provides an additional degree of freedom for performance tuning. Finally, two prototype balun filters are designed and fabricated at 3.48 and 1.80 GHz, respectively. Measured results achieve good filtering and balun performance and agree well with those from simulations.

Dual-Band Circularly Polarized Pentagonal Slot Antenna

Abstract: A novel design is described for a dual-band circularly polarized pentagonal slot antenna. The circular polarization (CP) radiation characteristics are achieved by loading with proper asymmetry, which is placed at the opposite angle of the feed line. A prototype of the proposed design is implemented and measured. Measured results show that radiation patterns with good CP characteristics are obtained at the two resonant frequencies.

Experimental Analysis of a Wideband Pattern Diversity Antenna With Compact Reconfigurable CPW-to-Slotline Transition Feed

Abstract: A wideband antenna with a reconfigurable coplanar waveguide (CPW)-to-slotline transition feed is proposed for pattern diversity applications. The feed provides three modes -CPW feed, left slotline (LS) feed and right slotline (RS) feed- without extra matching structures. Changes between modes are controlled by only two p-I-n diodes. Features of the proposed switchable feed include compact size and simple bias circuit. The equivalent transmission line model is used in the analysis of the proposed design. A prototype of the proposed antenna is fabricated, tested, and the obtained results including reflection coefficient, radiation patterns and gains, are present. A measurement of channel capacity is carried out to prove the benefit of pattern diversity when using the proposed antenna in both line-of-sight (LOS) and non-line-of-sight (NLOS) communication scenarios.

Compact and Tunable Slot-Loop Antenna

Abstract: A compact and tunable slot-loop antenna is studied in this communication. By periodically loading the slot line with varactor diodes, the slow-wave loop is capable of operating at frequencies from 2.34 GHz to 4 GHz with the measured input reflection coefficient better than -7.5 dB while occupying a small footprint of 0.072 λg × 0.072 λg (8.1 mm × 8.1 mm), where λg is the guided wavelength of a slot line at 2.34 GHz. The slot-loop in the ground plane is excited by a simple microstrip line, which enables the impedance matching from 3.2 GHz to 4 GHz for VSWR ≤ 2. A LC low-pass circuit is configured into the bias network to isolate the RF signal from the DC power path and consistent radiation patterns are experimentally obtained across the entire tunable frequencies of interest. The slot loop combined with the feed line and the bias circuitry is only 40 mm × 38.97 mm. Experimental results validate the feasibility of the presented antenna and agree well with simulation data.

RFID devices using metamaterial antennas

Abstract: A radio frequency identifier (RFID) tag can comprise an RFID chip, an antenna, and a feed line electrically coupling the RFID chip to the antenna. An encoded information reading (EIR) terminal can comprise a microprocessor, a memory communicatively coupled to the microprocessor, a communication interface, and an EIR device provided by a bar code reading device, an RFID reading device, or a card reading device. The RFID reading device can further comprise an antenna and a feed line. The antenna for the RFID tag or for the RFID reading device can be provided by a patch cell, a patch cell array comprising two or more patch cells, or by a patch cell stack comprising two or more patch cells. An equivalent circuit for the patch can comprise at least two inductances and a shunt capacitance. An equivalent circuit for the patch cell array can comprise two or more inductance groups connected via a series capacitance and two or more shunt capacitances. An equivalent circuit for the patch cell stack can comprises two or more capacitances connected via a series inductance and two or more shunt inductances. The antenna can have a composite right- and left-handed (CRLH) structure.

Single-Feed Dual-Band Dual-Linearly-Polarized Proximity-Coupled Patch Antenna

Abstract: In this paper, two novel single-feed dual-band dual-polarized microstrip antennas, fed by proximity coupling, are presented. The first approach begins with a new patch antenna that provides dual-band dual-polarized operation by means of an open-circuit stub, added at the open end of the feed line. By adding a stub to the end of the feed line, one can make an antenna with two resonant frequencies. The first resonant frequency is approximately the same as that in the initial design, but the second frequency depends on the stub's length, the stub's location, and the location of the feed point across the patch's width. Moreover, the variation of the feed-line location with respect to the patch's length has no significant effect on the first resonance frequency, while the second frequency changes. The second approach that is studied to realize a dual-band dual-polarized design utilizes a microstrip-gap proximity-coupled feed mechanism. Further insight is sought through the investigation of the surface-current densities on the proposed patch antennas at their resonant frequencies. The radiation performance - including radiation pattern, cross polarization, and gain - is satisfactory within two bands. The CST simulation results and measurement results showed good agreement with each other.

Compact Band-Rejected Ultrawideband Slot Antennas Inserting With and Resonators

Abstract: Two compact ultrawideband (UWB) slot antennas with band-rejected characteristics are proposed for UWB com- munication applications. The entire size of both antennas is as small as , which is smaller than most of the proposed UWB antennas. The radiator is a stepped slot excited by a 50 feed line. By etching a half-wavelength and a quarter-wavelength slot from the ground plane of UWB slot antennas, respectively, two UWB antennas with band-notched characteristics can be obtained. The potential interference be- tweenUWBandWLAN/WiMAXcanbereduced.Omnidirectional radiation patterns and constant gain can be observed in the pass bands. Time-domain characteristics of both proposed antennas are analyzed under different conditions. It demonstrates that the time-domain characteristics of the antennas are good enough for UWB applications. The results show that proposed antennas are very suitable for various portable UWB systems.

A Printed Wide-Slot Antenna With a Modified L-Shaped Microstrip Line for Wideband Applications

Abstract: A printed wide-slot antenna for wideband applications is proposed and experimentally investigated in this communication. A modified L-shaped microstrip line is used to excite the square slot. It consists of a horizontal line, a square patch, and a vertical line. For comparison, a simple L-shaped feed structure with the same line width is used as a reference geometry. The reference antenna exhibits dual resonance (lower resonant frequency f1, upper resonant frequency f2). When the square patch is embedded in the middle of the L-shaped line, f1 decreases, f2 remains unchanged, and a new resonance mode is formed between f1 and f2 . Moreover, if the size of the square patch is increased, an additional (fourth) resonance mode is formed above f2. Thus, the bandwidth of a slot antenna is easily enhanced. The measured results indicate that this structure possesses a wide impedance bandwidth of 118.4%, which is nearly three times that of the reference antenna. Also, a stable radiation pattern is observed inside the operating bandwidth. The gain variation is found to be less than 1.7 dB.

Serial Aperture-Coupled Dual Band Circularly Polarized Antenna

Abstract: In this innovative method of producing circular polarized (CP) wave, we present a serial feed line which couples diamond-shaped slot to ring and cross-slot to patch. The feed line is used to feed the two parts in series. Then, the structure can easily be operated as a dual band circularly polarized antenna to cover both 0.915 GHz and 2.45 GHz bands. Experimental results show that the proposed antenna has good circular polarization characteristics.

Wideband Dual-Frequency Dual-Polarized Dipole-Like Antenna

Abstract: A wideband dual-frequency dual-polarized printed antenna is proposed for LTE, WLAN, and UWB systems. The dual-band antenna provides wide impedance bandwidths of 74% with respect to the center frequency of 2.725 GHz, and 39% with respect to the center frequency of 7.15 GHz. An open slot in the ground plane between the feed arms provides an orthogonal path to realize an embedded circularly polarized band at 2.35 GHz with an axial-ratio bandwidth of 16%. Dual-band characteristics are achieved by an asymmetrical dipole-like element and the coupling configuration between the T-shaped feed line and the wide ground-plane slot.

Twinaxial linear induction antenna array for increased heavy oil recovery

Abstract: A radio frequency applicator and method for heating a hydrocarbon formation is disclosed. An aspect of at least one embodiment disclosed is a linear radio frequency (RF) applicator. It includes a transmission line and a current return path that is insulated from the transmission line and surrounds the transmission line to create a coaxial conductor. At least one conductive sleeve is positioned around the transmission line and the current return path. The transmission line and the current return path are electrically connected to the conductive sleeve. A radio frequency source is configured to apply a signal to the transmission line. When the linear applicator is operated, a circular magnetic field forms, which creates eddy current in the formation causing heavy hydrocarbons to flow. The applicator provides enhanced oil recovery where steam may not be used.

Bandwidth Improvements Using Ground Slots for Compact UWB Microstrip-fed Antennas

Abstract: The paper studies the method of using a ground slot for bandwidth improvement of compact ultra-wide band (UWB) antennas with microstrip line feed. Slots of difierent shapes such as triangular, rectangular, partially circular and hexagonal, placed on the ground plane under the feed line of the radiator are studied for impedance matching. The efiects of the slots on the performances of the antennas, in terms of impedance bandwidth, radiation pattern, gain, and e-ciency, are studied. Results of simulation tests show that a ground slot with proper dimensions placed under the feed line can improve the impedance matching and hence increase the bandwidth without afiecting much the performance of the antenna. Results of studies also show that, by using a hexagonal slot on the ground plane under the feed line, a patch antenna with a compact size of 35mm £ 23mm can achieve a bandwidth of 3.1{16.3GHz for S11 < i10dB. Moreover, it has a stable omnidirectional radiation pattern across the whole bandwidth and achieves an average gain of 2.8dBi and an average e-ciency of about 88% across the UWB.

Radar apparatus provided with series-feed array-antennas each including a plurality of antenna elements

Abstract: A radar apparatus forming a series-feed array-antenna includes an array antenna having transmission/reception antennas, and each antenna includes a plurality of antenna elements arrayed with feed-lines to be series-connected each other. A calibration line is disposed between the transmission antenna and the reception antenna via a switch which connects or disconnects the calibration line. The signal having a phase shift is transmitted via the calibration line when the switch connects the calibration line and an amount of phase shift from the signal transmitted via the calibration line is calculated based on a reference phase at the transmission antenna thereby calibrating the phase shift.

An active artificial transmission line for squint-free series-fed antenna array applications

Abstract: A transmission line periodically loaded with an active circuit generating a non-Foster negative capacitance is presented As a result of this loading, a special true time delay line is obtained over a broad frequency range The remarkable attribute of this line is that its phase velocity exceeds the speed of light in vacuum and remains linear with frequency which is impossible for passive true time delay lines The design procedure along with simulation results are presented This line can be employed in squint-free series-fed antenna arrays as well as in squint-free leaky-wave antennas and in delay control circuits

Remote antenna unit with external power control using a single control line

Abstract: Apparatus and methods for efficient external control of the transmit power of a remote fixed gain antenna unit in RF communications. Apparatus embodiments include a separate feeding unit coupled to a remote fixed gain antenna unit through a single coaxial line. The feeding unit is operative to provide transmit control signals to the remote antenna unit based on power feedback created in the remote antenna unit and sent to the feeding unit over the single coaxial line. Feedback and transmit/receive control inputs are transmitted through the single coax line together with RF signals. The coax line may be long. The apparatus and methods may be used in a vehicular environment.

A UWB antenna combined with a reconfigurable bandpass filter for cognitive radio applications

Abstract: A single-port small-size antenna for cognitive radio (CR) applications is presented. The antenna is based on an ultra-wideband (UWB) design and has a reconfigurable bandpass filter integrated in its feed line. The UWB operation is required for the sensing task in a CR system. Upon activating the filter, the UWB frequency response is transformed into a tunable narrowband one, which is needed for the communication task.

Compact CPW‐FED printed monopole antenna with super‐wideband performance

Abstract: This letter presents a new printed monopole antenna with super-wideband performance useful for various ultra wideband communication applications. The antenna has a compact structure, and the total size is 24 × 24 × 1.6 mm3. The antenna structure consists of a hexagonal patch radiator with a modified 50 Ω coplanar waveguide line for excitation. By using a trident shaped feed line structure the super wide bandwidth is obtained. Measurement results show that the impedance bandwidth for S11 ≤ −10 dB is enhanced largely to more than 174%. Radiation patterns are given at 4, 6, and 9.5 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26090

Multiband slot-ring antenna with single- and dual-capacitive coupled patch for wireless local area network/worldwide interoperability for microwave access operation

Abstract: A compact size slot-ring antenna design with a dual operating band that satisfies both wireless local area network and worldwide interoperability for microwave access operation is proposed. To achieve optimum impedance matching for both lower and upper operating bands, an inner circular radiating patch is capacitively coupled with the open end of a coplanar waveguide feed line, thereby demonstrating wideband characteristics from 1.97 to 4.25 GHz with a voltage standing wave ratio (VSWR) of 2:1 for the lower band, whereas the broad upper band which is excited owing to a pair of protruding stubs from the feed line can cover between 4.92 and 5.93 GHz. Further investigation on the method for a dual-capacitive coupled patch design is performed, whereby the inner circular patch is divided into two halves that are coupled with each other. The design process and initial characteristics of the two proposed antennas will be discussed in detail via simulated, and experimental results with satisfactory performance are observed within all bands of interest.

Design of a Miniaturized UWB Antenna with Band-Notched and High Frequency Rejection Capability

Abstract: To prevent potential Electromagnetic Interference (EMI), a miniaturized UWB antenna with notched band of 5.15–5.825 GHz and high frequency (over 10.6 GHz) rejection capability is proposed and investigated. The notched band of 5.15–5.825 GHz is created by etching a U-shaped slot on the feed line. The characteristic of high frequency cutoff (over 10.6 GHz) is realized by integrating a serpentine resonator on the backside of the radiating element. The results, including voltage standing wave ratio (VSWR), radiation patterns and gain responses, are evaluated by means of both simulations and experiments. The measured results matched simulated ones. Finally, the group delay of the antenna is also evaluated. Compared with original antenna (without U-shaped slot and serpentine resonator), the antenna minimized potential EMI of the out of UWB band and the WLAN band effectively.

Single transmission line for connecting radio frequency modules in an electronic device

Abstract: A millimeter-wave radio frequency (RF) system, and method thereof for transferring multiple signals over a single transmission line connected between modules of a millimeter-wave RF system. The system comprises a single transmission line for connecting a first part of the RF system and a second part of the RF system, the single transmission line transfers a multiplexed signal between the first part and second part, wherein the multiplexed signal includes intermediate frequency (IF) signal, a local oscillator (LO) signal, a control signal, and a power signal; the first part includes a baseband module and a chip-to-line interface module for interfacing between the baseband module and the single transmission line; and the second part includes a RF module and a line-to-chip interface module for interfacing between the RF module and the single transmission line, wherein the first part and the second part are located away from each other.

Dielectrically Loaded Antenna and Radio Communication Apparatus

Abstract: A backfire dielectrically loaded antenna for operation at a frequency in excess of 200 MHz includes a dielectric core having a relative dielectric constant greater than 5 and having an outer surface defining an interior volume the major part of which is occupied by solid material of the core; a three-dimensional antenna element structure including at least one pair of elongate conductive antenna elements disposed on or adjacent the side surface portion of the core and extending from a distal core surface portion towards a proximal core surface portion; a feed structure having an axially extending elongate laminate board including a transmission line section acting as a feed line which extends through a passage in the core from the distal core surface portion to the proximal core surface portion, and an antenna connection section having an integrally formed proximal extension of the transmission line section the width of which, in the plane of the laminate board, is greater than the width of the passage; and an impedance matching section coupling the antenna elements to the feed line.

Wide-Band Linked-Ring Antenna Element for Phased Arrays

Abstract: Technologies for a wide-band linked-ring antenna element covering two adjacent K-band military and/or commercial receive bands are provided. The antenna element comprises a linked-ring conductive resonator that is electromagnetically coupled to at least one feed line. The conductive resonator and feed line are further surrounded by a Faraday cage that is conductively coupled to an electromagnetically-shielding ground plane and operable to shield the conductive resonator and the feed line.

Broadband Characteristics of a Planar Folded Dipole Antenna with a Feed Line

Abstract: Various planar folded dipole antennas with feed lines are introduced and analyzed. With the added feed line, the planar folded dipole antenna has two resonance modes. Moreover, adjusting the spacing and width of the feed line improves the broadband characteristics of the antenna. The attached feed line has not only an impedance transforming characteristic but also a bandwidth transforming characteristic. The bandwidth transforming characteristic means that the feed line can broaden the bandwidth of folded dipole antenna. A way to reduce the antenna area is also studied, and the characteristics of the resulting compact antenna are analyzed.

Radio frequency power amplifier protection system

Abstract: A radio frequency (RF) power amplifier protection system for a radio. The protection system utilizes a resistive tap connected to the drain of a power amplifier transistor and a high speed voltage detector. The protection system uses short, low-power tests pulses to determine the quality of an antenna load upon tuning the radio to an RF carrier frequency by transmitting the short test pulse. If the measured voltage value exceeds a calibrated value, the power of the RF transmitter is reduced for subsequent operation or the RF transmitter is shut down completely. The invention also includes a system and method for detecting when an antenna is disconnected from a radio using an low frequency AC signal to measure the resistance of an antenna connected to an RF transmitter.

An RF front-end for multi-channel direct RF sampling cable receivers

Abstract: This paper presents a broadband fully integrated high dynamic range RF front-end with a single-inductor programmable RF amplitude equalizer, 45dB variable gain range, 4.5dB NF, 60dB CSO/CTB, and 25dB anti-aliasing protection. It is designed in a 40GHz-ft BiCMOS 0.25μm process, consumes 400mW from a 3.3V supply, and enables a cable full-spectrum receiver to capture >16 channels over an 50MHz–1GHz RF band.