Showing papers on "Microstrip published in 2008"

Substrate Integrated Waveguide Cross-Coupled Filter With Negative Coupling Structure

Abstract: Substrate integrated waveguide (SIW) technology provides an attractive solution to the integration of planar and nonplanar circuits by using a planar circuit fabrication process. However, it is usually difficult to implement the negative coupling structure required for the design of compact canonical folded elliptic or quasi-elliptic cross-coupled bandpass filter on the basis of a single-layer SIW. In this paper, a special planar negative coupling scheme including a magnetic coupling post-wall iris and a balanced microstrip line with a pair of metallic via-holes is studied in detail. Two -band fourth-degree cross-coupled bandpass filters without and with source-load coupling using the negative coupling structures are then proposed and designed. The two novel SIW filters having the same center frequency of 20.5 GHz and respective passband width of 700 and 800 MHz are implemented on a single-layer Rogers RT/Duroid 5880 substrate with thickness of 0.508 mm. Measured results of those filters, which exhibit a high selectivity, and a minimum in-band insertion loss of approximately 0.9 and 1.0 dB, respectively, agree well with simulated results.

60-GHz Patch Antennas and Arrays on LTCC With Embedded-Cavity Substrates

Abstract: The design is presented of aperture-coupled microstrip line-fed patch antennas (ACMPAs) and 4times4 planar arrays on Ferro A6-S low-temperature cofired ceramic (LTCC) substrate operating in the 60-GHz frequency band. In addition to the traditional ACMPA design, air cavities processed inside the LTCC substrate are used to improve the bandwidth and gain of the antennas. The arrays are excited through the microstrip-line feed networks using quarter-wave matched T-junctions and using Wilkinson power dividers. The results show that ACMPAs and arrays can be fabricated with a standard LTCC process even for the millimeter-wave region. Good agreement is achieved between simulations and measurements. The measured S-parameters indicate impedance bandwidths of 9.5% and 5.8% for the array elements with and without an embedded cavity. The measured maximum gains for the 16-element patch arrays (with and without cavity) are 18.2 and 15.7 dBi, respectively.

A Compact Open-Loop Filter With Mixed Electric and Magnetic Coupling

Abstract: A novel cascaded microstrip open-loop resonator filter with controllable electric and magnetic mixed coupling is presented to have one or more transmission zeros. For two coupled resonators, the coupled sides with the maximum magnetic field are combined with their open gaps with the maximum electric field, creating the electric and magnetic mixed coupling. By adjusting the distances between resonators and the positions of open gaps in a mixed coupled filter, the coupling coefficients can be changed, and controllable transmission zeros can be produced in the lower stopband, upper stopband, or both. Design and fabrication of the proposed second-and fourth-order filters show the advantages: such as a smaller number of resonators, higher rejection level, as well as asymmetrical response; moreover, the location of the transmission zeros can be precisely controlled.

A Novel Single-Feed Circular Microstrip Antenna With Reconfigurable Polarization Capability

Abstract: A single-feed circular microstrip antenna with reconfigurable polarization capability is proposed. This antenna has a simple structure, which consists of a radiating circular patch, five switches (PIN diode), three matching stubs, and a 50 microstrip feed line. It can be switched between 4 different states: two states (low-frequency and high-frequency) for linear polarization (LP), one state for left hand circular polarization (LHCP) and one for right hand circular polarization (RHCP) by controlling the bias voltage of two PIN diodes. At the same time, three switchable matching stubs are used for matching every polarization state. Simulation results and experimental results show that the proposed antenna demonstrates a low cross polarization level, good impedance bandwidth, and a very good axial ratio in the circularly polarized states.

Design of Dual-Band Bandpass Filters Using Stub-Loaded Open-Loop Resonators

Abstract: In this paper, open-loop resonators loaded by shunt open stubs are proposed to design compact dual-band bandpass filters with improved out-of-band rejection characteristics. The second passband of the dual-band filter is obtained by tuning higher resonant modes of the open-loop resonator by the stub length and position. A tapped-line input/output feed structure is used for external coupling. Required external coupling is obtained by adjusting the tapping position and dimension of the stub-loaded resonator. A lossless transmission line model is used to determine the resonance properties of the resonator and the external quality factor. Theoretical predictions are verified by the experimental results of three dual-band filters.

Ultra-Wideband Power Divider With Good In-Band Splitting and Isolation Performances

Abstract: An ultra-wideband (UWB) power divider on microstrip line is proposed, analyzed and designed. This divider is formed by installing a pair of stepped-impedance open-circuited stubs and parallel-coupled lines to two symmetrical output ports. In addition, a single resistor is properly placed between two output ports. After simple transmission line theory analysis, it is demonstrated that 3 dB power splitting from one input to two output ports, good impedance matching at all the three ports and excellent isolation between two output ports are achieved over the specified 3.1-10.6 GHz UWB range. Finally, a prototype divider is fabricated and measured to provide an experimental verification on the predicted attractive features.

A novel uwb elliptical slot antenna with band-notched characteristics

Abstract: This paper presents a novel band-notched elliptical slot antenna for Ultra Wide-Band (UWB) communication, which is printed on a dielectric substrate of RT/duroid 6006 with relative permittivity (er) of 6.0, thickness of 1.27 mm, and fed by an elliptical open ended microstrip line connected to the 50 Ω main line. This antenna is designed to be used in frequency band of 3.1–10.6 GHz. Bandnotched characteristics of antenna to reject the frequency band of 5.15–5.825GHz, which is limited by IEEE 802.11a, is realized by parasitic inverted-U strip attached to the elliptical slot plane. Effects of varying the parameters of parasitic inverted-U strip on performance of proposed antenna have been investigated. The antenna with optimal parameters obtained from parametric study is fabricated and measured. It is observed that the simulation and experimental results have good agreements with each other. 128 Fallahi, Kalteh, and Golparvar Roozbahani

Full-Wave Modal Dispersion Analysis and Broadside Optimization for a Class of Microstrip CRLH Leaky-Wave Antennas

Abstract: In this paper, a planar microstrip composite right/left-handed leaky-wave antenna is analyzed and designed as an infinite 1-D periodic microstrip leaky-wave antenna. A parametric study, based on a full-wave numerical modal approach that analyzes a unit cell using a periodic layered-medium Green's function, is shown to be an efficient approach to accurately design the structure, completely eliminating open-stopband effects and achieving an almost constant radiation efficiency when the beam is scanned through broadside. Results obtained by the proposed approach are compared with those obtained by means of both an artificial transmission-line analysis and a Bloch-wave analysis, which use the full-wave simulation of a finite-length structure. The balanced condition is interpreted in terms of the behavior of the phase and attenuation constants relevant to the radiating harmonic. Furthermore, it is shown how radiation at broadside is guaranteed by the presence of two radiating elements (one series and one shunt) within the equivalent circuit of the unit cell. The effectiveness of the analysis is demonstrated through the design of a finite-length antenna excited by a source at one end.

Design of Novel Dual-Band Bandpass Filter with Microstrip Meander-Loop Resonator and CSRR DGS

Abstract: A novel dual-band bandpass filter with meander-loop resonator and complement split-ring resonator (CSRR) defected ground structure (DGS) is proposed in this letter. Microstrip meanderloop resonator and CSRR DGS are operated for respective passbands. Several finite attenuation poles in stopbands are realized to improve the selectivity of the proposed bandpass filter and isolation between the two passbands. Compact size, dual band and high selectivity characteristics are realized by this type of filter structure. The filter is evaluated by experiment and simulation with very good agreement.

Design and Measurement of Reconfigurable Millimeter Wave Reflectarray Cells With Nematic Liquid Crystal

Abstract: Numerical simulations are used to study the electromagnetic scattering from phase agile microstrip reflectarray cells which exploit the voltage controlled dielectric anisotropy property of nematic state liquid crystals (LCs). In the computer model two arrays of equal size elements constructed on a 15 mum thick tuneable LC layer were designed to operate at center frequencies of 102 GHz and 130 GHz. Micromachining processes based on the metallization of quartz/silicon wafers and an industry compatible LCD packaging technique were employed to fabricate the grounded periodic structures. The loss and the phase of the reflected signals were measured using a quasi-optical test bench with the reflectarray inserted at the beam waist of the imaged Gaussian beam, thus eliminating some of the major problems associated with traditional free-space characterization at these frequencies. By applying a low frequency AC bias voltage of 10 V, a 165deg phase shift with a loss 4.5-6.4 dB at 102 GHz and 130deg phase shift with a loss variation between 4.3-7 dB at 130 GHz was obtained. The experimental results are shown to be in close agreement with the computer model.

A Novel Approach to the Design and Implementation of Dual-Band Power Divider

Abstract: This paper presents the design of a new Wilkinson power divider for dual-band application. The proposed circuit also features a simple structure with realistic impedance values, distributed design with reduced parasitic effect (in compared to lumped component), and exact solution (ideal characteristics). Closed-form design equations are derived using the even-and odd-mode formulation. For verification, the measured results of a microstrip power divider operating at 1 and 2 GHz is shown.

A Single Layer Wideband U-Slot Microstrip Patch Antenna Array

Abstract: The design and measured results of a 2 times 2 microstrip line fed U-slot rectangular antenna array are presented. The U-slot patches and the feeding network are placed on the same layer, resulting in a very simple structure. The advantage of the microstrip line fed U-slot patch is that it is easy to form the array. An impedance bandwidth (VSWR < 2) of 18% ranging from 5.65 GHz to 6.78 GHz is achieved. The radiation performance including radiation pattern, cross polarization, and gain is also satisfactory within this bandwidth. The measured peak gain of the array is 11.5 dBi. The agreement between simulated results and the measurement ones is good. The 2 times 2 array may be used as a module to form larger array.

RF MEMS Actuated Reconfigurable Reflectarray Patch-Slot Element

Abstract: This paper describes the design of a reconfigurable reflectarray element using commercially available radio frequency micro-electromechanical system (RF MEMS) switches. The element consists of a microstrip patch on the top surface and a slot with an actuated variable length in the ground plane. RF MEMS switches are mounted on the slot to electronically vary the slot length by actuating the switches and thus obtaining the desired phase response. Waveguide measurements and high frequency structure simulator (HFSS) simulations are used to characterize the reflectarray element. The four MEMS switches element gives 10 independent states with a phase swing of 150 deg and a loss variation from 0.4 dB to 1.5 dB at 2 GHz (more switches can provide larger phase shift). The loss is mainly attributed to the dielectric loss and the conductor loss, which occur due to the relatively strong electric fields in the substrate region below the patch and the large currents on the top surface of the patch, respectively, close to the patch resonance. Detailed analysis is performed to characterize the effect of the switches by taking into consideration the switch model and wire bonding effects.

Narrow-band, tunable infrared emission from arrays of microstrip patches

Abstract: We demonstrate through a combination of theory and experiment that an array of microstrip patches leads to a surface with sharp and tunable emission bands. The physical mechanisms and locations for various emission peaks are described via both analytical theory and numerical simulations. These predictions agree well with our experimental data, taken on systems designed to emit strongly in the infrared. The main peak, which arises from plasmons trapped under a patch, can be well separated from other spectral structures, narrow in wavelength, but broad in angular distribution.

High-frequency transmission line connection structure, circuit board, high-frequency module, and radar device

Abstract: The invention relates to a high-frequency transmission line connection structure, a circuit board having the connection structure, a high-frequency module having the circuit board, and a radar apparatus. A first laminated waveguide sub-line part (21) includes a pair of main conductor layers that oppose each other in a thickness direction with a dielectric layer (31) having the same thickness as a dielectric layer (31) of a microstrip line (1) interposed therebetween. A second laminated waveguide sub-line part (22) includes dielectric layers (31, 32) thicker than the dielectric layer of the first laminated waveguide sub-line part (21). A laminated waveguide main-line part (23) includes dielectric layers (31, 32, 33) thicker than the dielectric layers of the second laminated waveguide sub-line part (22). A conversion part (10) connected to the microstrip line (1) is formed by integrating with an upper main conductor layer constituting the respective line parts.

Comparison of the Radiation Efficiency for the Dielectric Resonator Antenna and the Microstrip Antenna at Ka Band

Abstract: The radiation efficiency of a dielectric resonator antenna (DRA) and a microstrip antenna (MSA) at Ka band is investigated numerically and experimentally. For direct comparison, one cylindrical DRA and one circular disk MSA were designed with similar feeding networks for operation at around 35 GHz. The efficiency of both devices was measured using the directivity/gain (D/G) method and the Wheeler cap method, in both of which the losses in the test system and the feeding structure were taken into account for calibration purposes. A good agreement between measured and simulated results for both methods is found, when considering the effect of the sampling interval and cross-polarization in the D/G method and the effect of the metallic cap size in the Wheeler cap method. It is finally demonstrated that the radiation efficiency of the DRA is significantly higher than that of the MSA at millimeter wave frequencies.

Investigations Into Phase Characteristics of a Single-Layer Reflectarray Employing Patch or Ring Elements of Variable Size

Abstract: The paper reports on investigations into phase characteristic of a unit cell of a single-layer microstrip reflectarray, which includes patch or ring elements of variable size. The aim is to have a smaller gradient (slower slope) of the reflected wave phase as a function of the elements' size to achieve a wider operational bandwidth and smaller susceptibility to manufacturing errors. The results obtained for single resonance elements demonstrate that a slower slope can be achieved using thicker substrates at the expense of an inadequate phase range of less than 300deg. This inadequate phase range leads to the reflectarray elements phase errors, which reduce its directivity. To overcome this problem the use of multiresonance multiring elements is postulated. It is shown that square and circular shaped multiple rings printed on a thick substrate can offer a slower phase slope and the phase range exceeding 360deg. The achieved slopes and ranges of double rings are comparable with those of double stacked patches printed on the equivalent low permittivity dielectric substrate. Choosing suitable dimensions of double-ring elements, the phase characteristic can be made approximately a linear function of their size.

Quarter-Wavelength Side-Coupled Ring Resonator for Bandpass Filters

Abstract: This paper deals with a dual-mode ring resonator fed by quarter-wavelength side-coupled lines. The resonator synthesis was developed so as to fix the central frequency, bandwidth, and transmission zeros frequencies, as well as the insertion loss in the passband. Based on this resonator, several bandpass filters were designed, which include the cascaded rings and the combination of such ring resonator with coupled line sections. Simulations are proposed throughout the paper to illustrate the various possibilities offered by the concept. The filters' experimental results in microstrip technology are also presented to validate the idea.

Implementation of Compact UWB Bandpass Filter With a Notch-Band

Abstract: An ultra-wideband (UWB) bandpass filter on microstrip line with notch-band, compact-size and improved upper-stopband performances is presented and implemented. A modified non-uniform resonator is at first formed by transversely attaching three pairs of impedance-stepped stubs. Its resonance behavior is thoroughly characterized so as to allocate the first three resonant frequencies within 3.1-10.6 GHz band while suppressing spurious harmonics in the upper-band. As this resonator is linked at two sides with two feed lines via interdigital coupled lines with enhanced coupling degree, a preferred UWB passband is realized. Then, one of two arms in the coupled-line sections is largely extended and folded, aiming to create a notch band at the frequency of 5.6 GHz by virtue of out-of-phase transmission cancellation. Two filter prototypes are optimized and fabricated to demonstrate the notch-band-included and upper-stopband-improved UWB bandpass performances.

Printed Wide-Slot Antenna for Wideband Applications

Abstract: The design and analysis of a novel printed wide-slot antenna, fed by a microstrip line, for wideband communication systems is presented. Detailed simulation and experimental investigations are conducted to understand its behavior and optimize for broadband operation. The designed antenna has a wide operating bandwidth of over 120% (2.8-11.4 GHz) for S11 <-10 dB. In addition to being small in size, the antenna exhibits stable far-field radiation characteristics in the entire operating bandwidth, relatively high gain, and low cross polarization. By properly choosing the suitable slot shape, selecting similar feed shape and tuning their dimensions, the design with very wide operating bandwidth, relatively small size and improved radiation pattern is obtained. A comprehensive parametric study has been carried out to understand the effects of various dimensional parameters and to optimize the performance of the designed antenna. Results show that the impedance matching of this kind of antenna is greatly affected by the feed-slot combination and feed gap width, with the slot shape being a main contributor of the radiation characteristics. The simulated and measured Results for return loss, far-field E and H-plane radiation patterns, and gain of designed antenna are presented and discussed.

Dual-Frequency Dual-Sense Circularly-Polarized Slot Antenna Fed by Microstrip Line

Abstract: A new design of a dual-frequency dual circularly-polarized slot antenna is presented. The dual-frequency is achieved using a single-layer microstrip-fed configuration coupled to a modified annular-slot antenna. The dual sense circular-polarization is obtained by four unequal linear slots which augment the annular slot. Experimental results show the proposed antenna has good circular polarization characteristics for both right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP). The 10 dB return loss impedance bandwidths for the lower (RHCP) and higher (LHCP) bands are 26.7% and 11.3%, respectively. The 3 dB axial-ratio bandwidths are 6.1% and 6.0% with respect to 1.5 GHz (RHCP) and 2.6 GHz (LHCP), respectively.

Two Novel Band-Notched UWB Slot Antennas Fed by Microstrip Line

Abstract: Two kinds of band-notched ultra wide-band slot antennas are proposed. Printed on a dielectric substrate of FR4with relative permittivity of 4.4 and fed by a 50 Ω microstrip line, the proposed antennas introduce semicircular annular strips to reject the frequency band (5.15-5.85 GHz) limited by IEEE802.11a. The parameters which affect the performance of the antennas in terms of its frequency domain characteristics are investigated in this paper.

Printed Slot Planar Inverted Cone Antenna for Ultrawideband Applications

Abstract: A novel ultrawideband (UWB) printed wide-slot antenna is presented. The design is based on the planar inverted cone antenna (PICA), introduced by Suh. The presented design comprises PICA-like structures, etched from a double-layer substrate. Compared to the original PICA, it is lower in profile, more compact and maintains comparable performance. A prototype integrated in a printed circuit board and fed by a microstrip line is fabricated and measured. The results show that the proposed antenna provides at least 13:1 impedance bandwidth at 10-dB return loss.

RF Receiving and transmitting apparatuses having a microstrip-slot log-periodic antenna

Abstract: A log-periodic antenna having a layer of dielectric media interposed between a microstrip log-periodic portion and a slot log-periodic portion where an array of two or more log-periodic antennas that may be placed about vehicles, such as air vehicles, or mounted on stationary structures, such as communication towers.

A Compact Dual-Band Bandpass Filter Using Meandering Stepped Impedance Resonators

Abstract: This letter presents a miniaturized dual-band narrow bandpass filter (BPF) using meandering stepped impedance resonators (SIRs) with a new coupling scheme, which exhibited a size reduction of 50% compared with the traditional direct coupling structure at the same frequency, while the new structure can generate three transmission zeros in the insertion loss response. To validate the design and analysis, two dual-band BPFs centered at 2.4-GHz/5.2-GHz and 2.4-GHz/5.7-GHz for WLAN application were fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The BPFs achieved insertion loss of less than 2 dB and return loss of greater than 16-dB in each band.

Permittivity and Loss Tangent Characterization for Garment Antennas Based on a New Matrix-Pencil Two-Line Method

Abstract: The emergence of wearable antennas to be integrated into garments has revealed the need for a careful electromagnetic characterization of textile materials. Therefore, we propose in this paper a new matrix-pencil two-line method that removes perturbations in the calculated effective permittivity and loss tangent which are caused by imperfect deembedding and inhomogeneities of the textile microstrip line structure. The approach has been rigorously validated for high-frequency laminates by comparing measured and simulated data for the resonance frequency of antennas designed using the calculated parameters. The method has been successfully applied to characterize the permittivity and loss tangent of a variety of textile materials and up to a frequency of 10 GHz. Furthermore it is shown that the use of electrotextiles in antenna design influences the effective substrate permittivity.

Development of Ultrawideband Antenna With Multiple Band-Notched Characteristics Using Half Mode Substrate Integrated Waveguide Cavity Technology

Abstract: Investigations on planar ultrawideband (UWB) antenna with multiple band-notched characteristics based on half mode substrate integrated waveguide technology are presented. The proposed antenna consists of a planar UWB monopole antenna and a half mode substrate integrated waveguide cavity which can generate multiple stopbands by proper arrangement. Planar antennas with dual, triple and quadruple notched bands are designed and implemented. The notched frequencies and their bandwidths can be adjusted according to specification by altering the cavity and feed line independently. These antennas are fabricated with two-layer printed circuit board (PCB) process. Sharp and high band rejection, narrow frequency notches are achieved, which are in good agreement with the simulated results. This technique is suitable for designing wideband antenna with multiple frequency notches or for creating multiband antennas.

Stopband-Expanded Low-Pass Filters Using Microstrip Coupled-Line Hairpin Units

Abstract: In this letter, a class of stopband-expanded low-pass filters (LPFs) is proposed via attenuation poles of microstrip coupled-line hairpin unit. By centrally tap-connecting this coupled-line unit and adjusting its coupling strength, three attenuation poles can be excited above the desired low passband. A coupled-line-oriented closed-form model is then constructed to provide a physical insight into the excitation of these poles and to execute an efficient synthesis design of this LPF. Two prototype filters with single and two units are finally designed with the specified cutoff frequency at 2.5 GHz. Measured results of the fabricated filters evidently demonstrate good LPF performance, sharp roll-off skirt, and a wide upper-stopband of 3.2 to 11.8 GHz with the insertion loss higher than 20.0 dB.

Compact Rat-Race Coupler Using Shunt-Stub-Based Artificial Transmission Lines

Abstract: In this letter, a compact rat-race coupler is developed using shunt-stub-based artificial transmission lines (SSB ATLs). A conventional quarter-wavelength microstrip can be equivalent to an SSB ATL realized by two series high-impedance microstrips with the high-impedance branch-type shunt stubs. The circuit configuration of the SSB ATL is beneficial to miniaturize the circuit size using the folding technique. By integrating six SSB ATLs, a compact rat-race coupler can be implemented with a 3.9% circuit size of the conventional one. The measured results of the developed rat-race coupler are in a good agreement with the simulated results by full-wave electromagnetic simulator.

Folded Half Mode Substrate Integrated Waveguide 3 dB Coupler

Abstract: In this letter, novel compact 3 dB double-slot and single-slot couplers are proposed and implemented based on folded half mode substrate integrated waveguide (FHMSIW) The size of the FHMSIW coupler is reduced by nearly 50% and 75% compared with half-mode substrate integrated waveguide coupler and substrate integrated waveguide coupler, respectively Prototype couplers at X-band are fabricated and measured and good performance in bandwidth, insertion loss, and balance are achieved