Showing papers on "Return loss published in 2005"

Ultra-wideband (UWB) bandpass filters using multiple-mode resonator

Abstract: A novel microstrip-line ultra-wideband (UWB) bandpass filter is proposed and implemented using a multiple-mode resonator (MMR), aiming at transmitting the signals in the whole UWB passband of 3.1-10.6GHz. In the design, the first three resonant frequencies of this MMR are properly adjusted to be placed quasiequally within the UWB. Then, the parallel-coupled lines at the two sides are longitudinally stretched so as to raise the frequency-dispersive coupling degree with the coupling peak near the center of the UWB. After optimization of this filter, a good UWB bandpass behavior with five transmission poles is theoretically realized and experimentally confirmed. Within the whole UWB passband, the return loss is found higher than 10dB, and the group delay variation is less than 0.23ns.

On-chip antennas for 60-GHz radios in silicon technology

Abstract: The recent advances in 60-GHz radios have called for the parallel development of compact and efficient millimeter-wave antennas. This brief addresses for the first time the design, fabrication, and characterization of on-chip inverted-F and quasi-Yagi antennas for 60-GHz radios. The design was made using the Zeland IE3D software package. The fabrication was realized with the back-end-of-line process of silicon substrates of low resistivity 10 /spl Omega//spl middot/cm. The characterization was conducted on wafer with Cascade Microtech coplanar probes and an HP8510XF network analyzer. The results show that the inverted-F antenna achieved a minimum return loss of 32 dB and a gain of -19 dBi at 61 GHz; while the quasi-Yagi antenna achieved a minimum return loss of 6.75 dB and a gain of -12.5 dBi at 65 GHz. Good agreement has been observed between the measured and simulated results.

Study of CPW-fed circular disc monopole antenna for ultra wideband applications

Abstract: The paper presents a study of coplanar waveguide (CPW) fed circular disc monopole antenna for ultra-wideband (UWB) applications. A circular disc monopole printed on a dielectric substrate and fed by a 50 /spl Omega/ CPW on the same layer can yield an ultra-wide -10 dB return loss bandwidth with satisfactory radiation patterns. The performance and characteristics of the antenna are investigated in order to understand its operation. Good agreement has been obtained between the simulation and experiment.

An electronically tunable microstrip bandpass filter using thin-film Barium-Strontium-Titanate (BST) varactors

Abstract: A tunable third-order combline bandpass filter using thin-film barium-strontium-titanate varactors and fabricated on a sapphire substrate is reported. Application of 0-200-V bias varied the center frequency of the filter from 2.44 to 2.88 GHz (16% tuning) while achieving a 1-dB bandwidth of 400 MHz. The insertion loss varied from 5.1 dB at zero bias to 3.3 dB at full bias, while the return loss exceeded 13 dB over the range. The third-order intercept of the filter was found to be 41 dBm.

A differential 4-bit 6.5-10-GHz RF MEMS tunable filter

Abstract: This paper presents a state-of-the-art RF microelectromechanical systems wide-band miniature tunable filter designed for 6.5-10-GHz frequency range. The differential filter, fabricated on a glass substrate using digital capacitor banks and microstrip lines, results in a tuning range of 44% with very fine resolution, and return loss better than 16 dB for the whole tuning range. The relative bandwidth of the filter is 5.1 /spl plusmn/ 0.4% over the tuning range and the size of the filter is 5 mm /spl times/ 4 mm. The insertion loss is 4.1 and 5.6 dB at 9.8 and 6.5 GHz, respectively, for a 1-k/spl Omega//sq fabricated bias line. The simulations show that, for a bias line with 10-k/spl Omega//sq resistance or more, the insertion loss improves to 3 dB at 9.8 GHz and 4 dB at 6.5 GHz. The measured IIP/sub 3/ level is > 45 dBm for /spl Delta/f > 500 kHz, and the filter can handle 250 mW of RF power for hot and cold switching.

A 12-18-GHz three-pole RF MEMS tunable filter

Abstract: This paper presents a state-of-the-art RF microelectromechanical systems (MEMS) wide-band tunable filter designed for the 12-18-GHz frequency range The coplanar-waveguide filter, fabricated on a glass substrate using loaded resonators with RF MEMS capacitive switches, results in a tuning range of 40% with very fine resolution, and return loss better than 10 dB for the whole tuning range The relative bandwidth of the filter is 57/spl plusmn/04% over the tuning range and the size of the filter is 8 mm/spl times/4 mm The insertion loss is 55 and 82 dB at 178 and 122 GHz, respectively, for a 2-k/spl Omega//sq bias line The loss improves to 45 and 68 dB at 178 and 122 GHz, respectively, if the bias line resistance is increased to 20 k/spl Omega//sq The measured IIP/sub 3/ level is >37 dBm for /spl Delta/f>200 kHz To our knowledge, this is the widest band planar tunable filter to date

A broadband series power divider using zero-degree metamaterial phase-shifting lines

Abstract: A metamaterial 1:4 series power divider that provides equal power split to all four output ports over a large bandwidth is presented, which can be extended to an arbitrary number of output ports. The divider comprises four nonradiating metamaterial lines in series, incurring a zero insertion phase over a large bandwidth, while simultaneously maintaining a compact length of /spl lambda//sub 0//8. Compared to a series power divider employing conventional one-wavelength long meandered transmission lines to provide in-phase signals at the output ports, the metamaterial divider provides a 165% increase in the input return-loss bandwidth and a 155% and 154% increase in the through-power bandwidth to ports 3 and 4, respectively. In addition, the metamaterial divider is significantly more compact, occupying only 2.6% of the area that the transmission line divider occupies. The metamaterial and transmission line dividers exhibit comparable insertion losses.

A broadband Wilkinson balun using microstrip metamaterial lines

Abstract: A metamaterial balun that converts a single-ended input to a differential output over a large bandwidth is presented. The device also exhibits excellent return loss, isolation, and through characteristics over the same frequency band. The balun comprises a Wilkinson divider, followed by a +90/spl deg/ negative-refractive-index (NRI) metamaterial (MM) phase-shifting line along the top branch, and a -90/spl deg/ MM phase-shifting line along the bottom branch. Utilizing MM lines for both the +90/spl deg/ and -90/spl deg/ branches allows the slopes of their phase responses to be matched, resulting in a broadband differential output signal. The theoretical performance of the balun is verified through circuit simulations and measurements of a fabricated prototype at 1.5 GHz. The MM balun exhibits a measured differential output phase bandwidth (180/spl deg//spl plusmn/10/spl deg/) of 1.16 GHz (77%), from 1.17 to 2.33 GHz. The measured isolation and return loss for all three ports remain below -10 dB over a bandwidth in excess of 2 GHz, while the output quantities |S/sub 21/| and |S/sub 31/| remain above -4 dB from 0.5 to 2.5 GHz.

A new wide-band planar balun on a single-layer PCB

Abstract: A new wide-band microstrip balun implemented on a single-layer printed circuit board (PCB) is presented in this letter. The proposed planar balun consists of a wide-band Wilkinson power divider and a noncoupled-line broad-band 180/spl deg/ phase shifter. To demonstrate the design methodology, one prototype is realized. The new design was simulated and validated by the measurement. Measured results show that 10-dB return loss of the unbalanced port has been achieved across the bandwidth from 1.7 GHz to 3.3 GHz, or 64%. Within the operation band, the measured return losses for both the two balanced ports are better than -10 dB, and the balanced ports isolation is below -1.5 dB. The measured amplitude and phase imbalance between the two balanced ports are within 0.3 dB and /spl plusmn/5/spl deg/, respectively, over the operating frequency band.

Linear tunable phase shifter using a left-handed transmission line

Abstract: We demonstrate a compact, linear, and low loss variation hybrid phase shifter using a left-handed (LH) transmission line. For frequencies from 4.3 to 5.6 GHz, this phase shifter gives a nearly linear phase variation with voltage, with a maximum deviation of /spl plusmn/7.5/spl deg/. Within this frequency range, the maximum insertion loss is 3.6 dB, and the minimum insertion loss is 1.8 dB over a continuously adjustable phase range of more than 125/spl deg/, while minimum return loss is only 10.2 dB. Furthermore, this phase shifter requires only one control line, and it consumes almost no power.

Dielectric embedded ESPAR (DE-ESPAR) antenna array for wireless communications

Abstract: A novel dielectric embedded electronically steerable passive array radiator (ESPAR) (DE-ESPAR) antenna array for mobile wireless communication terminal is developed by finite element method based numerical modeling technique. The size reduction of the seven-element monopole antenna was accomplished by embedding the array in a cylindrical rod of FIK ceramic complex with a relative permittivity around /spl epsiv//sub r/=4.5. Dielectric embedded prototypes of a seven-element ESPAR antenna array were modeled and experimentally characterized. Experimental and numerical results are in good agreement. The optimized antenna produced a horizontal directivity of 5.1 dBi and return loss of 19 dB at 2.48 GHz. An overall volume reduction of 80% and footprint reduction of 50% were achieved.

CPW-fed compact monopole antenna for dual-band WLAN applications

Abstract: A compact CPW-fed monopole antenna is proposed for dual-band wireless local area network (WLAN) operations The proposed antenna, which consists of two strips, has compact size of 20/spl times/155/spl times/16 mm/sup 3/ including the ground The proposed antenna effectively covers both 24 GHz (24-2484 GHz) and 5 GHz (515-5825 GHz) bands The measured peak gains are 13 dBi at 244 GHz and 28 dBi at 532 GHz

Low-loss LTCC cavity filters using system-on-package technology at 60 GHz

Abstract: In this paper, three-dimensional (3-D) integrated cavity resonators and filters consisting of via walls are demonstrated as a system-on-package compact solution for RF front-end modules at 60 GHz using low-temperature cofired ceramic (LTCC) technology. Slot excitation with a /spl lambda/g/4 open stub has been applied and evaluated in terms of experimental performance and fabrication accuracy and simplicity. The strongly coupled cavity resonator provides an insertion loss 20.6 dB over the passband (/spl sim/0.89 GHz), and a 3-dB bandwidth of approximately 1.5% (/spl sim/0.89 GHz), as well as a simple fabrication of the feeding structure (since it does not require to drill vias to implement the feeding structure). The design has been utilized to develop a 3-D low-loss three-pole bandpass filter for 60-GHz wireless local area network narrow-band (/spl sim/1 GHz) applications. This is the first demonstration entirely authenticated by measurement data for 60-GHz 3-D LTCC cavity filters. This filter exhibits an insertion loss of 2.14 dB at the center frequency of 58.7 GHz, a rejection >16.4 dB over the passband, and a 3-dB bandwidth approximately 1.38% (/spl sim/0.9 GHz).

Compact microstrip low-pass filter with sharp rejection

Abstract: This letter presents a compact multisection sharp-rejection microstrip low-pass filter. Each section consists of a microstrip line section and an interdigital capacitor. The analysis for optimizing the attenuation poles by adjusting the finger number, and the width and length of the microstrip line section, is presented. The cascaded four-section low-pass filter has a return loss of better than 17 dB and an insertion loss of less than 0.7 dB from DC to 1.6 GHz. The rejection is better than 20 dB from 2.1 to 7.5 GHz.

A dual-feed dual-band L-probe patch antenna

Abstract: By embedding shorting vias, a dual-feed and dual-band L-probe patch antenna, with flexible frequency ratio and relatively small lateral size, is proposed. Dual resonant frequency bands are produced by two radiating patches located in different layers, with the lower patch supported by shorting vias. The measured impedance bandwidths, determined by 10 dB return loss, of the two operating bands reach 26.6% and 42.2%, respectively. Also the radiation patterns are stable over both operating bands. Simulation results are compared well with experiments. This antenna is highly suitable to be used as a base station antenna for multiband operation.

A miniaturized Wilkinson power divider with CMOS active inductors

Abstract: A miniaturized Wilkinson power divider implemented in a standard 0.18-/spl mu/m CMOS process is presented in this letter. By using active inductors for the circuit implementation, a significant area reduction can be achieved due to the absence of distributed components and spiral inductors. The power divider is designed at a center frequency of 4.5GHz for equal power dividing with all ports matched to 50/spl Omega/. Drawing a dc current of 9.3mA from a 1.8-V supply voltage, the fabricated circuit exhibits an insertion loss less than 0.16dB and a return loss better than 30dB at the center frequency while maintaining good isolation between the output ports. The active area of the miniaturized Wilkinson power divider is 150/spl times/100/spl mu/m/sup 2/, which is suitable for system integration in monolithic microwave integrated circuit (MMIC) applications.

Dielectric-filled slotline bowtie antenna for breast cancer detection

Abstract: An ultra-wideband dielectric-filled antenna has been designed for the purpose of breast cancer detection. The antenna geometry is a modified version of a slotline bowtie hybrid, which is immersed in a dielectric medium, and fed with an integrated ultra-wideband balun. Simulations were performed on both the balun and the antenna separately. The antenna had a simulated time domain near-field beamwidth of 32/spl deg/. A return loss of 10 dB was obtained from 2.5 to 9 GHz, and 5 dB from 1 to 10 GHz. Both bandwidths were slightly smaller than simulated. A prototype was constructed and feasibility tests were performed on tumour models immersed in a breast phantom material. Measurements demonstrate detection of a 7 mm diameter tumour at a depth of 4 cm from the aperture.

A new printed G-shaped monopole antenna for dual-band WLAN applications

Abstract: A novel dual-band printed G-shaped monopole antenna is proposed. The antenna provides two resonant paths of different lengths (forming into a G-shaped profile) in order to achieve 2.4- and 5.2-GHz dual-band operation for WLAN applications. Reasonably large impedance-matching bandwidth and good radiation patterns have been observed. The measured impedance bandwidth for 10-dB return loss in the 2.4- and 5.2-GHz bands reaches 0.37 GHz (2.25–2.62 GHz) and 1.06 GHz (4.94–6 GHz), respectively. In addition, the proposed antenna has a small size of 13.6 × 9.3 mm2. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 295–297, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20800

Combined feed network for a shared-aperture dual-band dual-polarized array

Abstract: A new combined feed network is proposed for a shared-aperture dual-band dual-polarized array operating in the L/C band. The array comprises square, aperture-coupled patches in the C-band and a square perforated, aperture-coupled L-band patch. The feed networks of a single polarization for both the bands are combined into a single network on a single layer. Good return loss and radiation characteristics are obtained for L- and C-band frequencies.

Wideband coplanar waveguide-to-rectangular waveguide transition using fin-line taper

Abstract: This letter introduces a new wideband coplanar waveguide-to-rectangular waveguide transition. The transition uses a uniplanar circuit in line with the waveguide, which eases the design and fabrication. The design does not require airbridges. Simulations and measurements of X-band (8.2-12.4 GHz) transitions based on both a low- and high-permittivity material (/spl epsiv//sub r/= 2.33 and 10.8) show that the transition works fine over the full frequency band. For /spl epsiv//sub r/= 2.33 the measured return and insertion loss of a back-to-back transition are more than 16 dB and less than 0.4dB, respectively. The corresponding values for /spl epsiv//sub r/= 10.8 are more than 10 dB and less than 1.0 dB, respectively, over 90% of the frequency band. The measured insertion loss values indicate losses of less than 0.14 dB and 0.36 dB at the center frequency for a single transition on a substrate with /spl epsiv//sub r/= 2.33 and 10.8, respectively.

Wide-band stacked double annular-ring dielectric resonator antenna at the end-fire mode operation

Abstract: A novel wide-band stacked double annular-ring dielectric resonator antenna (DRA) is numerically investigated in this paper. At either layer, a larger annular-ring dielectric resonator is placed concentrically outside a smaller annular-ring one to form a stacked double annular-ring DRA. The antenna is operating at the end-fire mode. The effects of antenna parameters such as dielectric constant, probe length and air-gaps thickness are investigated. Compared to the obtained 18% bandwidth of the stacked annular-ring DRA, the proposed stacked double annular-ring DRA can offer an impedance bandwidth of /spl sim/42% for the return loss below -10 dB. The radiation patterns are stable in the passband.

Circularly polarized array antenna with corporate-feed network and series-feed elements

Abstract: In this paper, corporate-feed circularly polarized microstrip array antennas are studied. The antenna element is a series-feed slot-coupled structure. Series feeding causes sequential rotation effect at the element level. Antenna elements are then used to form the subarray by applying sequential rotation to their feeding. Arrays having 4, 16, and 64 elements were made. The maximum achieved gains are 15.3, 21, and 25.4 dBic, respectively. All arrays have less than 15 dB return loss and 3 dB axial ratio from 10 to 13 GHz. The patterns are all quite symmetrical.

Meandered multiband PIFA with coplanar parasitic patches

Abstract: A meandered multiband planar inverted-F antenna with two coplanar parasitic patches is presented. The antenna has a very wide impedance bandwidth of 743 MHz covering the frequencies from 1.765 to 2.508 GHz with the return loss L/sub rtn/ /spl ges/ 6 dB. The antenna also operates in the GSM band with a high radiation efficiency.

Superconducting spiral filters with quasi-elliptic characteristic for radio astronomy

Abstract: To produce a filter small enough to fit a 2-in wafer at 408 MHz while maintaining high-quality performance, half-wavelength single spiral microstrip resonators are introduced. New coupling structures make both positive and negative coupling available by changing the directions of spiral winding. An eight-pole high-temperature superconducting bandpass spiral filter with 3.7% bandwidth at 408-MHz band is presented for radio astronomy applications at the Jodrell Bank Radio Observatory, Macclesfield, Cheshire, U.K. A quasi-elliptic characteristic with four transmission zeros is realized by adding three cross-couplings to the standard Chebyshev filter. The filter shown is designed and fabricated on a 32 mm /spl times/ 18 mm /spl times/ 0.508 mm MgO substrate. The untuned measured results of the filter at 30 K show a maximum passband insertion loss 0.35 dB (ripple 0.27 dB), a minimum return loss 13.2 dB, and minimum out-of-band rejection of 65 dB, which have good agreement with its electromagnetic full-wave simulation results.

Dielectric rod waveguide antenna for W band with good input match

Abstract: Antennas based on dielectric rod waveguide made of GaAs and fused sapphire cut along its optical axis inserted in the end of a standard WR-10 metal waveguide are investigated with computer simulations and experiments in the W band. The radiation pattern is found to be similar to that of the open metal waveguide end, but less frequency-dependent beamwidth and input match: measured return loss is more than 25 dB.

A monolithic double-balanced direct conversion mixer with an integrated wideband passive balun

Abstract: This paper presents the design and performance characteristics of a 20-40 GHz monolithic double-balanced direct conversion mixer implemented using InGaP/GaAs HBT process. The compact MMIC mixer makes use of a Gilbert-cell multiplier and utilizes a broadband monolithic passive balun that has been developed for MMIC applications. The new balun makes use of multidielectric layer structure to achieve a broadband performance in a simple coplanar configuration. A measured return loss better than 15 dB, with a maximum insertion loss of 4.5 dB including the 3-dB power splitting loss has been achieved over the band from 15 to 45 GHz. Operated as a downconverter mixer, the newly developed direct conversion mixer achieves a measured conversion gain of 16 dB given an RF signal at 30 GHz, LO drive of 5 dBm and a downconverted baseband signal at 10 MHz. The mixer IP3 occurs at an output power of 4 dBm while the IP2 occurs at an output power of 11 dBm.

A new planar marchand balun

Abstract: In this paper, a novel planar Marchand balun using a patterned ground plane is presented. In the new design, with a slot under the coupled lines cut on the ground plane, the even-mode impedance can be increased substantially. Meanwhile, we propose that two additional separated rectangular conductors are placed under the coupled lines to act as two capacitors so that the odd-mode impedance is decreased. Design theory and procedure are presented to optimize the Marchand balun. As an example, one Marchand balun on a double-sided PCB is designed, simulated, fabricated and measured. The measured return loss is found to be better than - 10 dB over the frequency band from 1.2 GHz to 3.3 GHz, or around 100% bandwidth. The measured amplitude and phase imbalance between the two balanced output ports are within 1 dB and 4 0 , respectively, over the operating frequency band.

Bow-tie microstrip antenna design

Abstract: In this paper, the bow-tie microstrip antennas have been designed with two different angles of 40deg and 80deg. An investigation on the effect of the angle to the return loss and radiation patterns had been carried out. The impedance matching network with the microstrip transmission line feeding was used in this study. Simulation and measurement results for the return loss and radiation patterns were presented

A wide-band aperture coupled microstrip array antenna using inverted feeding structures

Abstract: A wide-band aperture coupled 2/spl times/4 microstrip array antenna using inverted feeding structures is presented for serving both Personal Communications Services and International Mobile Telecommunications-2000 services simultaneously. The measured bandwidth for 10 dB return loss at each port is 19.84% and 28.25%, respectively, which cover both services.

A dual band printed dipole antenna with spiral structure for WLAN application

Abstract: In this letter, the design procedure and electrical performance of a dual band (2.4/5.8GHz) printed dipole antenna using spiral structure are proposed and investigated. For the first time, a dual band printed dipole antenna with spiral configuration is proposed. In addition, a matching method by adjusting the transmission line width, and a new bandwidth broadening method varying the distance between the top and bottom spirals are reported. The operating frequencies of the proposed antenna are 2.4GHz and 5.8GHz which cover WLAN system. The proposed antenna achieves a good matching using tapered transmission lines for the top and bottom spirals. The desired resonant frequencies are obtained by adjusting the number of turns of the spirals. The bandwidth is optimized by varying the distance between the top and bottom spirals. A relative position of the bottom spiral plays an important role in achieving a bandwidth in terms of 10-dB return loss.