Showing papers on "Return loss published in 2004"

Double-sided printed bow-tie antenna for UWB communications

Abstract: This letter proposes a double-sided printed bow-tie antenna for ultra wide band (UWB) applications. The frequency band considered is 3.1-10.6 GHz, which has been approved by the Federal Communications Commission as a commercial UWB band. The proposed antenna has a return loss less than 10 dB, phase linearity, and gain flatness over the above frequency band.

Segmented transmission-line electroabsorption modulators

Abstract: We present segmented transmission-line (TML) electroabsorption modulators (EAMs) with characteristic impedance close to 50 /spl Omega/. The segmented TML approach allows us to design a traveling-wave EAM with 50 /spl Omega/ impedance and very high bandwidth. The devices show low return loss (<-15 dB) and excellent frequency response up to 50 GHz, and exhibit a maximum model-extrapolated 3 dBe bandwidth (BW) of 90 GHz. An effective modeling tool based on Bloch-wave analysis is derived. Design considerations and TML properties for periodic TML-EAMs are discussed.

Design of compact planar antennas using LH-transmission lines

Abstract: This contribution demonstrates the possibility to reduce the size of planar antennas by using LH-transmission lines. Two different types of radiators are investigated - a microstrip patch and a slotted cavity. A transmission line model is employed to design and compare these two approaches and their realization with a varying number of L-C loaded unit cells. Three representative antenna configurations have been selected and subsequently optimized with full wave electromagnetic analysis. Return loss and radiation pattern measurements of these antennas proof the developed concept.

Multiband folded planar monopole antenna for mobile handset

Abstract: This paper introduces a folded planar monopole antenna, which has a very low profile of about one twentieth of the wavelength of the lowest operating frequency. The effect is achieved by using a bended rectangular radiating patch and an inverted L-shape ground plane. The proposed antenna can be used in multiband operation, with omnidirectional radiation patterns for all operating bands. Its impedance bandwidth, determined by 10 dB return loss, covers almost all present wireless communication systems: Global System for Mobile Communication (GSM), Digital Communication System (DCS), Personal Communication System (PCS), Universal Mobile Communication System (UMTS), and Industrial Science Medical (ISM) band. This paper presents the design and experimental results of the proposed antenna. Moreover, the study also investigates the tuning effects of the geometry parameters on impedance matching.

Fabrication and accelerated hermeticity testing of an on-wafer package for RF MEMS

Abstract: A hermetic silicon micromachined on-wafer dc-to-40-GHz packaging scheme for RF microelectromechanical systems (MEMS) switches is presented. The designed on-wafer package has a deembedded insertion loss of 0.03 dB per transition up to 40 GHz (a total measured loss of 0.3 dB including a 2.7-mm-long through line) and a return loss below -18dB up to 40 GHz. The hermeticity of the packaged is tested using an autoclave chamber with accelerated conditions of 130/spl deg/C, 2.7 atm of pressure, and 100% relative humidity. The fabrication process is designed so as to be completely compatible with the MEMS switch process, hence, allowing the parallel fabrication of all the components on a single wafer. The on-wafer proposed packaging approach requires no external wiring to achieve signal propagation and, thus, it has the potential for lower loss and better performance at higher frequencies.

Broad-band microstrip-to-CPW transition via frequency-dependent electromagnetic coupling

Abstract: An improved broad-band microstrip-to-coplanar-waveguide (CPW) transition is developed on a basis of the frequency-dependence characteristic of an electromagnetic surface-to-surface coupling. A self-calibrated method of moments is extended to model this unbounded two-port discontinuity with the two dissimilar microstrip/CPW feeding lines. Numerical results are provided to demonstrate its frequency response of transmission under varied strip/slot dimensions and further exhibit its attractive ultra-broad-band transmission with low radiation loss. Next, the back-to-back transition circuits with the two different lengths are fabricated and measured to deembed in experiment the S-parameters of two single-transition structures. Predicted and measured results show good agreement with the return loss less than -10dB over the frequency of 3.2-11.2 GHz.

A flexible wearable antenna

Abstract: The paper describes the development of a flexible wearable antenna used in military and police work. The design is based on numerical simulations using commercial software. Simulations taking into account the curved-surface profile of the antenna and differently sized human bodies are presented. Experimentally obtained return loss and radiation patterns are shown in comparison with the computed results. Measured return loss better than 7 dB has been achieved across the frequency band of 360-460 MHz. The superiority of the antenna with respect to conventionally used antennas in the abovementioned applications is demonstrated.

Broadband folded Wilkinson power combiner/splitter

Abstract: A new folded Wilkinson power combiner/splitter has been realized at millimeter-wave frequency with an area that is one half that of the standard two-stage Wilkinson power combiner. The new splitter has an insertion loss of 5dB, an isolation of 15dB and a return loss 15dB from 15 to 45GHz.

Novel wide-band coplanar waveguide-to-rectangular waveguide transition

Abstract: A new coplanar waveguide (CPW)-to-rectangular waveguide transition is proposed for wide-band millimeter-wave applications. The transition has an in-line structure, which provides easy fabrication of the CPW circuit and waveguide block. An X-band (8.2-12.4 GHz) model has been designed and tested. Measurements of a back-to-back double transition have yielded a return loss of over 17 dB and an insertion loss of less than 0.5 dB over the full X-band. These results agree well with the simulated results obtained with a commercial electromagnetic structure simulator. In addition, this type of a transition has been designed and used for a local oscillator feed with a full F-band (90-140 GHz) coverage of a submillimeter-wave general-purpose harmonic mixer.

X-band TM01-TE11 mode converter with short length for high power

Abstract: A mode converter for X-band located between a generator and an antenna to convert TM01 to TE11 mode with high efficiency for a high power transmitting system is presented. The proposed mode converter has extended radius and excessive curvature with symmetric structure in order to convert between two modes efficiently with short length. The measured and simulated results of the return loss, mode patterns and efficiency of the proposed mode converter with 200 mm length are provided.

A broad-band quarter-wavelength impedance transformer with three reflection zeros within passband

Abstract: A new impedance transformer employing a transmission line and a coupled-line section is presented in this paper. It is physically a quarter-wavelength long, but can achieve three reflection zeros within the passband. Therefore, broad bandwidths can be obtained for a wide range of impedance ratios. The location of the reflection zeros can be synthesized through the transmission line and coupled-line parameters. Design curves for the transformer synthesis have been obtained by solving the design equations directly. Using these results, a stripline impedance transformer has been implemented. This 50-110-/spl Omega/ impedance transformer achieved over 25-dB return loss from 0.6 to 1.6 GHz.

An LTCC planar ultra-wideband antenna

Abstract: An ultra-wideband (UWB) planar volcano-smoke slot antenna realized using low-temperature cofired ceramic (LTCC) technology is reported in this paper. The antenna, developed for a single-package solution of UWB radio, hasimple single-layer structure and a small footprint of 23 × 23 mm2. The result shows that the prototype antenna achieves an impedance bandwidth of 9 GHz (with return loss S11 < −10 dB from 3 to 12 GHz). The antenna radiation pattern at frequencies 3.5, 6.85, and 10.1 GHz and gain versus frequency are also presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 220–222, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20257

Printed compact dual band antenna for 2.4 and 5 GHz ISM band applications

Abstract: A printed compact dipole antenna for dual ISM band (2.44 and 5 GHz) is presented. The proposed antenna fed by using a 50 /spl Omega/ coaxial line occupies a volume of 15/spl times/40/spl times/1 mm/sup 3/ (FR-4, permittivity 4.6). The impedance bandwidth for 10 dB return loss is about 400 MHz (from 2170 to 2570 MHz) at 2.4 GHz band and over 2300 MHz (from 4690 to beyond 7000 MHz) at 5 GHz band. The measured radiation gains range from 1.20 to 1.41 dBi at 2.4 GHz band and from 2.25 to 3.44 dBi at 5 GHz band, respectively.

Analysis and experimental validation of a triaxial antenna for microwave tumor ablation

Abstract: We apply a new triaxial antenna for microwave ablation procedures. The antenna consists of a coaxial monopole inserted through an 18-gauge biopsy needle positioned one quarter-wavelength from the antenna base. The biopsy needle creates a triaxial structure, which enhances return loss by more than 10 dB, thus limiting return currents along the feed line. Numerical simulations are used to optimize the antenna design. Numerical ex vivo experimental results are presented to quantify the field distribution, heating pattern and return loss of the antenna.

Analysis and design of coupled line impedance transformers

Abstract: Impedance transformers employing coupled line sections that are less than quarter wavelengths are presented in this paper. Exact solutions relating the coupled line parameters and arbitrary impedance transformation ratios are derived. This is unlike previous coupled line transformers, which were designed based on electromagnetic simulations and provide only impedance transformation ratios of 1:4. Various design curves demonstrating a wide range of practical coupled line parameter values are presented and validated with experimental results. A 50 /spl Omega/ to 170 /spl Omega/ impedance transformer using /spl lambda//8 coupled line section achieved over 10 dB return loss from 0.5 to 0.9 GHz.

Analysis of Circularly Polarized Dielectric Resonator Antenna Excited by a Spiral Slot

Abstract: The hemispherical dielectric resonator antenna (DRA) excited by a single-arm spiral slot is studied theoretically in this paper. The Green’s function technique is employed to formulate an integral equation for the spiral slot current. The moment method with piecewise sinusoidal (PWS) basis and testing functions is used to convert the integral equation into a matrix equation by using a deltagap exciting source. The input impedance, return loss, axial ratio and radiation pattern are calculated. Numerical results demonstrate that the analysis is efficient.

Compact coaxial-fed CP polarizer

Abstract: This letter describes the design and performance of a coaxial fed linear to circular polarization converter. The converter is 50% shorter, and has superior bandwidth response than conventional spread-squeeze alternatives. The polarizer is realized using metal posts positioned inside a circular waveguide. In the example given here, right-hand circular polarization over the frequency range of 8.0-8.6 GHz is generated with input return loss better than 20 dB, and axial ratio less than 2.5 dB.

A W-band surface micromachined monopole for low-cost wireless communication systems

Abstract: A W-band CPW-fed 3-D quarter-wavelength monopole that is vertically mounted on a variety of substrates is reported for the first time. A transition from coplanar waveguide to vertical coaxial structure is investigated. The structure demonstrates broadband impedance matching and symmetry radiation pattern in W-band. Greater than 10 dB return loss over 19 GHz bandwidth is measured on chromium coated soda-lime glass substrate, while over 10 GHz bandwidth for silicon and sapphire substrates is also observed in simulation. As a low-cost solution without etching requirements, this idea can be easily extended to integrate with other RF front-end components and to design more compact millimetre wave systems. Experimental and numerical simulation results are provided to demonstrate the effectiveness of the idea.

Narrow-band HTS filter on sapphire substrate

Abstract: This paper presents a narrow-band HTS bandpass filter on sapphire substrate for future mobile communications systems The filter is designed to have a five MHz pass band in the UMTS base stations receive band The filter exhibits a eight-pole quasi-elliptic function response implemented with a cascaded quadruplet coupling structure The filter was fabricated on a 043 mm-thick sapphire wafer with double-sided YBCO films The measured filter showed a midband insertion loss of 05 dB at 1973 MHz and a return loss better than -15 dB over the pass band It also exhibited an excellent rejection over the entire UMTS base station transmission band

A new Millimeter-wave printed dipole phased array antenna using microstrip-fed coplanar stripline tee junctions

Abstract: A new millimeter-wave printed twin dipole phased array antenna is developed at Ka band using a new microstrip-fed CPS tee junction, which does not require any bonding wires, air bridges, or via holes. The phased array used a piezoelectric transducer (PET) controlled tunable multitransmission line phase shifter to accomplish a progressive phase shift. A progressive phase shift of 88.8/spl deg/ is achieved with the 5 mm of perturber length when the PET has full deflection. Measured return loss of the twin dipole antenna is better than 10 dB from 29.5 to 30.35 GHz. Measured return loss of better than 15 dB is achieved from 30 to 31.5 GHz for a 1/spl times/8 phased array. The phased array antenna has a measured antenna gain of 14.4 dBi with 42/spl deg/ beam scanning and has more than 11 dB side lobe suppression across the scan.

Method and apparatus for determining at least an indication of return loss of an antenna

Abstract: A tone generator generates a test signal that a coupler injects into a cable towards an antenna. A receiver or other communication equipment, connected to the antenna via the cable, measures, across a frequency band, at least powers of a signal received at a base station from the antenna. The received signal includes a leakage signal and a reflected signal where the reflected signal is a reflected portion of the test signal and the leakage signal is a portion of the test signal leaking from the coupler away from the antenna. The communication equipment determines maximum and minimum powers of the received signal based on the measurements, and determines at least an indication of return loss of the antenna based on the determined maximum and minimum powers.

Practical realization of self-complementary broadband antenna on low-loss resin substrate for UWB applications

Abstract: Practical realizations of self-complementary ultra-wideband antennas on low-loss resin materials are demonstrated Dependences of broadband characteristics on sizes and shapes are clarified by simulations and experiments The self-complementary antennas impedance-matched to a 50-ohm system, utilizing a 3-stage Chebyshev transformer over the UWB band, were designed and fabricated on a resin material (the relative permittivity; /spl epsiv//sub r/=36) A measured return loss of less than -98 dB and a measured absolute gain of 0-3 dBi over a frequency range from 31 to 106 GHz (the UWB band) were obtained with a 30 mm/spl times/60 mm sized antenna A reduced sized antenna (20 mm/spl times/40 mm), designed and fabricated on a resin material of /spl epsiv//sub r/=102, delivered a return loss of less than -78 dB with an isotropic radiation pattern

PCB substrate integrated waveguide-filter using via fences at millimeter-wave

Abstract: In this paper, the implementation and the embedding method of the existing air-filled waveguide-filters at millimeter-wave on general Printed Circuit Board(PCB) substrate are introduced by systematically inserting the vias inside waveguide and mathematically manipulating the simple equations obtained from the classical circular-post waveguide the wave propagation. Because the mass production on PCB is possible without fabricating a large-scaled metal waveguide of WR-22 as input/output ports at millimeter-wave, th Bandpass-Filter(BPF) design procedure. Side walls and poles inside the waveguide are realized by placing two series array of via and tuning the via diameters. The each length of x, y, and z axes is reduced in proportion to root square of employed substrate dielectric constant and, especially, the length of z-axis can be more reduced due to the characteristics of e manufacturing cost can be reduced considerably. Finally, when using multi-layer process like low temperature cofired ceramic(LTCC) for small-sized module, it is one of advantages to use only one layer for the filter fabrication. To evaluate the validity of this novel technique, order-3 Chebyshev BPF centered at 40 GHz-band with a 2.5% Fractional Bandwidth(FBW) was used. The employed substrate has relative dielectric constant of 2.2 and thickness of 10 mils of Rogers RT/Duroid 5880. According to design and measurement results, a good performance of insertion loss of 2 dB and return loss of -30 dB is achieved at full input/output ports.

2.45GHz circularly polarized RFID reader antenna

Abstract: In this paper, an aperture coupled circularly polarized microstrip antenna was presented for RFID applications. It shows good impedance and radiation characteristics over 2.35 GHz to 2.55 GHz: gain is more than 9.0 dBic; return loss is less than -13 dB. The prototype is compact, light, simple, and low cost, it is suitable to use for RFID as the reader antenna

Design of corrugated horn antennas by evolutionary optimization techniques

Abstract: Corrugated horn antennas are frequently used as the feed elements in reflector antennas for satellite and deep space communications. A particular application is the multifrequency feed horns for the reflector antennas of the JPL/NASA Deep Space Network (DSN). In this application, it is desirable to design a horn that has a nearly perfect circularly symmetric pattern (i.e., identical E- and H-plane patterns), with zero or low cross-polarization, a specified beam width, and a low return loss at the design frequency range. A parametric study of the corrugated horns, however, shows that the objective function relating the pattern shape, beam width and return loss is a nonlinear function of the corrugation dimensions with many local optima. As a result one has to resort to global optimization techniques, such as evolutionary algorithms, for successful design of such antennas. Here, an evolutionary programming (EP) algorithm is used to optimize the pattern of a corrugated circular horn subject to various constraints on return loss, antenna beam width, pattern circularity, and low cross-polarization. Examples of design synthesis for a few corrugated horns are presented. The results show excellent and efficient optimization of the desired horn parameters.

Compact PIFA for 2.4/5 GHz dual ISM-band applications

Abstract: A compact and novel modified planar inverted-F antenna (PIFA) for dual ISM-band application is proposed. The proposed antenna, including a small ground plane, occupies a volume of 20/spl times/23.7/spl times/0.8 mm/sup 3/ (FR-4). The impedance bandwidth with 10 dB return loss is about 150 MHz (2380-2530 MHz) for 2.4 GHz band and 1450 MHz (5130-6580 MHz) for 5 GHz band. The measured radiation patterns are approximately omnidirectional and yield a gain of 1.0 dBi at 2440 MHz and 3.98 dBi at 5600 MHz, respectively.

A CPW-Fed Broadband Slot Antenna with Linear Taper

Abstract: A new coplanar waveguide (CPW)-fed broadband printed slot antenna is presented. The impedance bandwidth is greatly increased by using a linear taper. The test antenna's impedance bandwidth of −10-dB return loss reaches 40% with low cross-polarization level. The impedance characteristics and radiation patterns of the slot antenna with different sizes of tapers are presented. The simulated results agree well with the measured ones. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 218–221, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20098

Dc-50 GHz low-loss wafer-scale package for RF MEMS

Abstract: This paper reports on the design and fabrication of wafer-scale packaging for RF MEMS devices. Coplanar waveguide (CPW) lines on a glass wafer are covered with a high resistivity silicon wafer using gold-to-gold thermo-compression bonding. Oxide is used as a dielectric interlayer for CPW feedthrough underneath the gold sealing ring. The designed feedthrough has an insertion loss of 0.06-0.1 dB at 1-50 GHz with a retnrn loss of < -35 dB (per transition). The gold sealing ring is connected tu the CPW ground to achieve around 10 dB higher isolation. The whole package has a measured insertion loss of 0.2-0.5 dB and return loss of < -20 dB up to 50 GHz. The measured insertion loss at 1-2 GHz is 0.2 dB with return loss of < -30 dn.

Design for electrical performance of wideband multilayer LTCC microstrip-to-stripline transition

Abstract: A high impedance compensation technique is proposed to improve the wideband performance of the microstrip-to-stripline transition for multilayer LTCC substrate. A section of high impedance transmission line, which induces additional inductance, is added between the transition and 50 /spl Omega/ transmission line to compensate the capacitance of the transition. In the paper, various lengths and widths of the high impedance transmission line are simulated by HFSS and compared to optimize the electrical performance which achieves a return loss better than 17 dB over a band from DC to 70 GHz.