Parallel-strip Line Research Articles

A compact planar bandpass filter with wide out‐of‐band rejection implemented by substrate‐integrated waveguide and complementary split‐ring resonator

AbstractA compact planar bandpass filter is presented in this letter, which is implemented by the combination of three different electromagnetic structures, saying, substrate‐integrated waveguide (SIW), square complementary split‐ring resonators (CSRRs) and dumbbells slot.The resonator is formed by a SIW cavity loaded with some complementary split‐ring resonators (CSRRs) on its top metal plane, causing a stopband with a very sharp rejection. Meanwhile, several dumbbells are etched on the bottom plane of SIW just below each CSRR to enhance the coupling. Double‐sided parallel strip line (DSPSL) is also used to excite the SIW and guarantee good propagation between these two different structures. An X‐band prototype is designed and fabricated for demonstration, good agreement is observed between simulation and measurement, indicating a very wide rejection band ranging from 11 GHz to 23 GHz and quite strong suppression to spurious modes. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26079

A Novel Differential Dual-Band Bandpass Filter Based on Stepped-Impedance Double-Sided Parallel-Strip Line

A novel differential dual-band bandpass filter based on a stepped-impedance double-sided parallel-strip line is proposed in this article. In order to suppress the common-mode signal, an H-shaped ground plane is inserted. The simulated and measured results show that the proposed filter operated at 2.4 GHz and 5.8 GHz with the insertion losses of 3.2 dB and 3.5 dB, respectively. Also, the common-mode signal is suppressed to below −30 dB from 1 GHz to 7.5 GHz.

SUPER-WIDEBAND PRINTED ASYMMETRICAL DIPOLE ANTENNA

The proposed dipole antenna consists of two printed strips with unequal lengths and is fed by a coplanar strip (CPS) line. As the antenna parameters and port impedance are properly selected, a super wide operating band (jS11j < i10dB) of 3.5 to 20.0GHz is realized. Antenna samples were fabricated using standard PCB process. The area of the constructed dipole antenna is 40:0£5:0mm 2 . The S-parameter measurement was performed via a transition (CPS to double-sided parallel strip line) and transformer (190 to 50Ohm). The measured fractional bandwidth achieved 139.3% (from 3.4 to 19.0GHz) as predicted, over which the antenna peak gain is better than 0dBi.

Broadband cloaking of large arbitrary object by Double-Sided Parallel-Strip Line

In this paper, transmission line cloaking for arbitrary objects with different dimensions is presented. Double-sided parallel-strip line network causes electromagnetic waves to be coupled to the network surrounding the object and pass them across it without forward and backward scattering. Using of these unloaded transmission lines makes the simplicity of the structure feasible. Achieving a broadband cloaking condition is the other advantages of the proposed structure. Large object cloaking is provided by the using of a new structure which has an empty space in the center of similar previous structures. Simulation results demonstrate the quality of cloaking for different dimensions in conventional and proposed structures.

A New Dual Band Power Divider with Extreme Power Dividing Ratio

This paper presents the design of a new dual band power divider realized on double-sided parallel-strip line (DSPSL). The proposed structure mainly features a simple planar structure with extreme power dividing ratio, wide bandwidth, excellent isolation and frequency-independent output phase performance for dual band application. Closed-form equations are derived for design parameters. For verification purpose, the simulated and measured results of a dual band power divider with power dividing ratio of 20:1 are shown.

Compact Planar Magic-T Based on the Double-Sided Parallel-Strip Line and the Slotline Coupling

Two compact planar magic-T structures implemented on the double-sided parallel-strip line (DSPSL) and the slotline coupling are proposed and demonstrated. Due to a metallic ground inserted into the middle of the substrate for the double-sided parallel-strip line, the E-plane DSPSL power divider thus shows an intrinsic 180° out-of-phase characteristic between the two input/ output ports. A transition between slotline and DSPSL is utilized to realize the H-plane input/output port of the magic-T. The equivalent circuits are derived for the design of the proposed planar multilayer magic-T. Good agreement between the measured and simulated results indicates that the fractional bandwidths for the two planar magic-T structures are 42.8% and 43.8%, respectively, while the amplitude and phase imbalance are less than 0.22 dB and 1.5°.

The Backfire-to-Broadside Symmetrical Beam-Scanning Periodic Offset Microstrip Antenna

A backfire-to-broadside beam-scanning antenna with a periodic structure is described. The proposed antenna consists of the offset double-sided parallel-strip lines (DSPSL). The characteristics of the offset DSPSL have been studied, and then a series of offset DSPSL have been applied as the periodic antenna with a backfire-to-broadside symmetrical beam scanning capability. Both in plane and plane, main beams symmetrically steer from the backfire direction to the broadside direction with the increase of the operating frequency. The fractional impedance bandwidth has been broadened to nearly 50% by using the offset DSPSL structure.

Full-Space Scanning Periodic Phase-Reversal Leaky-Wave Antenna

A novel full-space scanning periodic phase-reversal leaky-wave antenna array is proposed, designed in offset parallel stripline technology, and demonstrated experimentally. This antenna radiates from its small phase-reversing cross-overs, which leads to a small leakage factor and subsequently a large directivity. The operation principle of the antenna is explained from the Brillouin diagram, which shows how single-beam scanning, using the m = -1 space harmonic, is achieved as a result of the π lateral shift of the dispersion curves due to phase reversal. One of the benefits of phase reversal is to permit this radiation performance with relatively small permittivity substrates (ee,min = 4 compared to ee,min = 9 for antennas without phase reversal). An unitcell matching technique is applied to avoid reflections, and thereby prevent the presence of an open stopband so as to permit continuous space scanning with efficient broadside radiation. An efficient array synthesis procedure, based on a transmission line modeling of the structure, is utilized for the design of the antenna following specifications in terms of frequency, scanning, directivity, radiation efficiency, and sidelobe level. A uniform-aperture antenna prototype, including a balun-transformer input transition, is presented, featuring experimental beamwidth and gain at the broadside frequency (25 GHz) of 4° and 15.7 dBi, respectively.

Performance enhancement of microwave circuits using parallel-strip line

Nowadays, demands for compactness, light weight, and broadband have a great impact on design issues at both component and system levels in wireless communications. Multilayered structures fabricated with low-temperature co-fired ceramic (LTCC) technologies have been developed recently in response to these demands. With this trend, double-sided printed circuits using conventional fabrication techniques with lower cost have been receiving plenty of attention. The parallel-strip line, belongs to the family of balanced transmission lines. The conventional printed circuit board technology is able to realize it easily. It is a simple structure comprised of a piece of dielectric substrate sandwiched by two conducting traces. Signals flowing on the upper and lower conductors are always equal in magnitude and 180° out of phase; therefore, parallel-strip line has an inherent advantage of easy realization of a balanced configuration. Balanced or double balanced microwave circuits, such as amplifier, mixer, and antenna, are frequently employed in high-performance wireless communications systems, and they can be directly fed by parallel-strip lines. In contrast, microstrip line is an unbalanced transmission line; therefore, extra effort of designing balanced to unbalanced structures (balun) is required for using microstrip transmission lines.

A Pair of Ultra-Wideband Planar Transitions for Phase Inversion Applications

A pair of planar transitions which produce ultra-wideband (UWB) in-phase and inverted-phase signals has been developed for phase-inversion circuit applications. The two similar transitions consist of three transitional structures between microstrip line, coplanar waveguide, and parallel stripline. The proposed transitions offer design flexibility in achieving a wide range of impedances with various substrates. The implemented transitions provide low insertion loss, good impedance matching, and UWB performance from 2.1 to over 25 GHz within ±5° phase difference from 180°.

Wideband Phase-Reversal Antenna Using a Novel Bandwidth Enhancement Technique

A novel bandwidth enhancement technique for phase-reversal Franklin-type antennas is proposed. Impedance bandwidth enhancement is achieved by combining several coupled modes of the antenna structure through periodic loading provided by radiating crossover dipoles. This technique is explained by the theory of periodically loaded transmission lines. Radiation pattern bandwidth enhancement is achieved by exciting the antenna in its center so as to suppress beam squinting by superposing the tilted beams of two resulting sub-arrays on either side of the feed. An offset parallel stripline (OPS) phase-reversal antenna using these bandwidth enhancement techniques is demonstrated theoretically and experimentally at 35 GHz. The antenna is printed on a thin substrate suspended over a micro-machined conductor-backed cavity for unidirectional radiation. The overall fractional bandwidth of the antenna is increased from 3% to over 11% compared to the conventional design and the antenna efficiency exceeds 80%.

A Novel Ultra-Wideband Differential Filter Based on Double-Sided Parallel-Strip Line

In this letter, double-sided parallel-strip line (DSPSL) has been used to build a novel differential filter with ultra- wideband (UWB) response. Swap structures, based on DSPSL, are employed in the design to realize 180° phase shift. So the swap structures can realize the conversion between differential- and common-mode. Utilizing the characteristic, the input common- mode signals will be cancelled at the center of the filter, while the input differential-mode signals can propagate in the proposed filter. The proposed new differential filter was calculated in analytical method, and was simulated by the full-wave electromagnetic simulator, and was validated by the measurement. The last results show they have a good in-band and out-band performance. With fractional bandwidth of 110% centered at 3 GHz, the differential-mode signals can propagate with UWB frequency response, while the common-mode signals are suppressed below -20 dB in the whole frequency band.

A Compact Parallel-Plane Perpendicular-Current Feed for a Modified Equiangular Spiral Antenna

The design and measurement is described of a compact (59.94 mm × 59.94 mm × 1.14 mm) bidirectional ultrawideband modified equiangular spiral antenna with an integrated feed internally matched to a 50-Ohm microstrip transmission line. An ultrawideband transition from microstrip to parallel-strip line soldered to a short (1.14 mm) twin-line transmission line feeds the spiral. The currents on the feed travel in a direction approximately perpendicular to the direction of the currents on the spiral at the points where the feed passes the spiral in close proximity (0.57 mm). Holes were etched from the metal arms of the spiral to reduce the impedance mismatch caused by coupling between the transmission line feed and the spiral. Measured and simulated radiation patterns and VSWR plots show good performance over the ultrawideband range (3.1-10.6 GHz) with a 2:1 VSWR everywhere in this range except for 3.33-3.95 GHz, which has a 3:1 VSWR. This spiral exhibits an elliptical polarization over the ultrawideband range.

Formula Derivation and Verification of Characteristic Impedance for Offset Double-Sided Parallel Strip Line (DSPSL)

Double-sided parallel strip line (DSPSL) is a versatile microwave transmission line. With an offset, it allows for large variations of the characteristic impedance and therefore flexibility for the design of novel microwave devices. In this letter, a formula for the characteristic impedance of DSPSL is derived by the fuzzy EM method and verified by commercial software. Very good agreement is observed.

Analysis and design of out-of-phase power divider with arbitrary division ratio

For the first time, an out-of-phase power divider with arbitrary division ratio is proposed. The design equations of the proposed power divider are derived by using odd- and even-mode analysis. It can be found that the arm with higher characteristic impedance couples more power than the one with lower impedance. Because the power divider is fed by the parallel-strip line at the input port, the phase difference between the two output ports is 180° and frequency-independent in the equal dividing case. A small phase offset (180° ± Δ) over a broad bandwidth can be mainly attributed to the asymmetrical structure in the unequal dividing case. Therefore only impedance bandwidth needs to be considered in this design. To verify the proposed idea, an unequal (2:1) out-of-phase power divider is designed and measured, showing a broad bandwidth from 1.375 to 2.3°GHz (about 50°). The simulated and measured results are presented and show good agreement.

Broadband compact rat-race hybrid and its application to mixers

A broadband rat-race hybrid with compact size using multilayer technology is presented. The bandwidth is 90% for amplitude balance &lt;±0.5 dB, phase balance &lt;±5°, isolation &lt;−20 dB and return loss &lt;−10 dB, while it is only 16% for a conventional microstrip rat-race hybrid. Meanwhile, this rat-race hybrid occupies only about 33% area of the conventional one. The theory of the proposed rat-race and the factors affecting the performance of the rat-race are studied. Furthermore, by properly integrating the double-sided parallel-strip line with microstrip line, this rat-race can facilitate circuit implementation. A single balanced mixer is designed and fabricated based on the new rate-race hybrid. It has several desirable features such as compactness, wide bandwidth, good interport isolations, and there is no need of wire jumper for intermediate frequency combining.

Low-loss ultra-wideband double-sided parallel-strip line transition and power divider

A low-loss transition from a coaxial transmission line to a double-sided parallel-strip line is presented, and a 0° power divider is demonstrated using this transition. Simulated results from CST Microwave Studio and measured results show good agreement and good performance over the ultra-wideband range (3.1–10.6 GHz).

1 mm ultrafast superconducting stripline molecule detector

Superconducting stripline detectors (SSLDs) are promising for detecting keV molecules at nanosecond response times and with mass-independent detection efficiency. However, a fast response time is incompatible with practical centimeter detector size. A parallel configuration of striplines provides a means to address this problem. Experimental results and simulation for promisingly large 1-mm-square parallel niobium SSLDs show that nanosecond pulses are produced by superconducting-normal transition within only one of the parallel striplines instead of cascade switching of all the parallel striplines. Successful detection of a series of multimers of immunoglobulin G up to 584 kDa supports the mass-independent efficiency for mass spectrometry.

Ultrawideband Composite Cavity-Backed Folded Sectorial Bowtie Antenna With Stable Pattern and High Gain

A composite cavity-backed folded sectorial bowtie antenna (FSBA) is proposed and investigated in this paper, which is differentially fed by an SMA connector through a balun, i.e. a transition from a microstrip line to a parallel stripline. The composite cavity as a general case, consisting of a conical part and a cylindrical rim, can be tuned freely from a cylindrical to a cup-shaped one. Parametric studies are performed to optimize the antenna performance. Experimental results reveal that it can achieve an impedance bandwidth of 143% for SWR les 2, a broadside gain of 8-15.3 dBi, and stable radiation pattern over the whole operating band. The total electrical dimensions are 0.66lambdam in diameter and 0.16lambdam in height, where lambdam is the free-space wavelength at lower edge of the operating frequency band. The problem about the distorted patterns in the upper frequency band for wideband cavity-backed antennas is solved in our work.

Enhanced CRLH Transmission Line Performances Using a Lattice Network Unit Cell

A novel topology for the composite right/left-handed transmission line (CRLH TL) is presented. This type of CRLH TLs has the advantage of exhibiting an all-pass behavior and a frequency-independent characteristic impedance, in the so-called balanced case. Moreover, it presents a larger group velocity than its conventional counterpart, thereby allowing for wider bandwidth operation. This letter investigates the fundamental properties of this structure, and demonstrates them by full-wave simulation and measurement results on a practical implementation in parallel stripline technology.