Showing papers on "Microstrip published in 2009"

Local Metamaterial-Based Waveguides in Gaps Between Parallel Metal Plates

Abstract: This letter presents a new metamaterial-based waveguide technology referred to as ridge gap waveguides. The main advantages of the ridge gap waveguides compared to hollow waveguides are that they are planar and much cheaper to manufacture, in particular at high frequencies such as for millimeter and sub- millimeter waves. The latter is due to the fact that there are no mechanical joints across which electric currents must float. The gap waveguides have lower losses than microstrip lines, and they are completely shielded by metal so no additional packaging is needed, in contrast to the severe packaging problems associated with microstrip circuits. The gap waveguides are realized in a narrow gap between two parallel metal plates by using a texture or multilayer structure on one of the surfaces. The waves follow metal ridges in the textured surface. All wave propagation in other directions is prohibited (in cutoff) by realizing a high surface impedance (ideally a perfect magnetic conductor) in the textured surface at both sides of all ridges. Thereby, cavity resonances do not appear either within the band of operation. The present letter introduces the gap waveguide and presents some initial simulated results.

Characterization of the Propagation Properties of the Half-Mode Substrate Integrated Waveguide

Abstract: The propagation properties of the half-mode substrate integrated waveguide (HMSIW) are studied theoretically and experimentally in this paper. Two equivalent models of the HMSIW are introduced. With the first model, equations are derived to approximate the field distribution inside and outside the HMSIW. Using the second model, an approximate closed-form expression is deduced for calculating the equivalent width of an HMSIW that takes into account the effect of the fringing fields. The obtained design formulas are validated by simulations and experiments. Furthermore, the attenuation characteristics of the HMSIW are studied using the multiline method in the frequency range of 20-60 GHz. A numerical investigation is carried out to distinguish between the contributions of the conductive, dielectric, and radiation losses. As a validation, the measured attenuation constant of a fabricated HMSIW prototype is presented and compared with that of a microstrip (MS) line and a substrate integrated waveguide (SIW). The SIW is designed with the same cutoff frequency and fabricated on the same substrate as the HMSIW. The experimental results show that the HMSIW can be less lossy than the MS line and the SIW at frequencies above 40 GHz.

Conductive Inkjet-Printed Antennas on Flexible Low-Cost Paper-Based Substrates for RFID and WSN Applications

Abstract: In this paper, a review of the authors' work on inkjet-printed flexible antennas, fabricated on paper substrates, is given. This is presented as a system-level solution for ultra-low-cost mass production of UHF radio-frequency identification (RFID) tags and wireless sensor nodes (WSN), in an approach that could be easily extended to other microwave and wireless applications. First, we discuss the benefits of using paper as a substrate for high-frequency applications, reporting its very good electrical/dielectric performance up to at least 1 GHz. The RF characteristics of the paper-based substrate are studied by using a microstrip-ring resonator, in order to characterize the dielectric properties (dielectric constant and loss tangent). We then give details about the inkjet-printing technology, including the characterization of the conductive ink, which consists of nano-silver particles. We highlight the importance of this technology as a fast and simple fabrication technique, especially on flexible organic (e.g., LCP) or paper-based substrates. A compact inkjet-printed UHF ldquopassive RFIDrdquo antenna, using the classic T-match approach and designed to match the IC's complex impedance, is presented as a demonstration prototype for this technology. In addition, we briefly touch upon the state-of-the-art area of fully-integrated wireless sensor modules on paper. We show the first-ever two-dimensional sensor integration with an RFID tag module on paper, as well as the possibility of a three-dimensional multilayer paper-based RF/microwave structure.

A Universal UHF RFID Reader Antenna

Abstract: A broadband circularly polarized patch antenna is proposed for universal ultra-high-frequency (UHF) RF identification (RFID) applications. The antenna is composed of two corner-truncated patches and a suspended microstrip line with open-circuited termination. The main patch is fed by four probes which are sequentially connected to the suspended microstrip feed line. The measurement shows that the antenna achieves a return loss of -15 dB, gain of 8.3 dBic, axial ratio (AR) of 3 dB, and 3-dB AR beamwidth of 75deg over the UHF band of 818-964 MHz or 16.4%. Therefore, the proposed antenna is universal for UHF RFID applications worldwide at the UHF band of 840-960 MHz. In addition, a parametric study is conducted to facilitate the design and optimization processes for engineers.

A Novel Technique for Open-Stopband Suppression in 1-D Periodic Printed Leaky-Wave Antennas

Abstract: A novel technique for the elimination of the open stopband in one-dimensional periodic printed leaky-wave antennas is presented. A quarter-wave transformer, or alternatively a matching stub, is introduced into the unit cell of the antenna, which forces the Bloch-wave impedance of the structure to remain real and non-zero at broadside. The effectiveness of the proposed technique is first demonstrated on a printed periodic microstrip leaky-wave antenna consisting of a single radiating stub per unit cell, which exhibits a significant stopband at broadside. The technique is then also applied to a structure consisting of two radiating stubs per unit cell, which is capable of mitigating, but not eliminating, the open stopband. In both cases the open stopband at broadside is completely suppressed.

On-chip integrated antenna structures in CMOS for 60 GHz WPAN systems

Abstract: This paper presents several on-chip antenna structures that may be fabricated with standard CMOS technology for use at millimeter wave frequencies. On-chip antennas for wireless personal area networks (WPANs) promise to reduce interconnection losses and greatly reduce wireless transceiver costs, while providing unprecedented flexibility for device manufacturers. This paper presents the current state of research in on-chip integrated antennas, highlights several pitfalls and challenges for on-chip design, modeling, and measurement, and proposes several antenna structures that derive from the microwave microstrip and amateur radio art. This paper also describes an experimental test apparatus for performing measurements on RFIC systems with on-chip antennas developed at The University of Texas at Austin.

Bandwidth Enhancement of a Microstrip-Line-Fed Printed Wide-Slot Antenna With a Fractal-Shaped Slot

Abstract: Microstrip-line-fed printed wide-slot antenna with a fractal-shaped slot for bandwidth enhancement is proposed and experimentally studied. By etching the wide slot as fractal shapes, it is experimentally found that the operating bandwidth can be significantly enhanced, and the relation between the bandwidth and the iteration order (IO) and iteration factor (IF) of the fractal shapes is experimentally studied. Experimental results indicate that the impedance bandwidth, defined by - 10 dB reflection coefficient, of the proposed fractal slot antenna can reach an operating bandwidth of 2.4 GHz at operating frequencies around 4 GHz, which is about 3.5 times that of a conventional microstrip-line-fed printed wide-slot antenna. It also achieved a 2-dB gain bandwidth of at least 1.59 GHz.

A Differential-Mode Wideband Bandpass Filter on Microstrip Line for UWB Application

Abstract: A differential-mode wideband bandpass filter (BPF) on microstrip line is proposed with good common-mode suppression. A four port two stage branch-line differential-mode BPF is first designed. Then, open circuited stubs are attached to the middle of two of the vertical branches. As such, its two-port bisection becomes a bandpass or bandstop filtering topology under differental- or common-mode excitations, respectively. The lengths and widths of these stubs can be properly adjusted to produce a highly attenuated and widened stopband under the common-mode operation. Finally, a wideband differential-mode BPF is designed and fabricated. The predicted and measured performances are in good agreement with each other, showing good common-mode suppression with an insertion loss higher than 20 dB over the differential-mode passband with a fractional bandwidth of 65%.

Phase-Encoded Chipless RFID Transponder for Large-Scale Low-Cost Applications

Abstract: A novel 3 b chipless RFID transponder is presented. The transponder comprises three microstrip patch antennas, which are loaded with open circuited (O/C) high impedance stubs. The antennas are resonant at nearby frequencies, and when excited with their respective resonant frequency signals, they re-radiate backscattered signals with distinct phase characteristics. This phase information is encoded as hexadecimal bits for the proposed chipless RFID tag. Both the CST Microwave Studio full-wave solver and the anechoic chamber measurements show a 30deg phase step for the 3 b chipless RFID transponder. It it easily transferred to printed technology, and it may find applications in the mass identification market.

A Compact Planar MIMO Antenna System of Four Elements With Similar Radiation Characteristics and Isolation Structure Hui Li, Student Member, IEEE, Jiang Xiong, Student Member, IEEE, and Sailing He, Senior Member, IEEE

Abstract: A compact planar multiple-input-multiple-output (MIMO) antenna system of four elements with similar radiation characteristics is proposed for the whole 2.4-GHz WLAN band. It consists of two proximity-coupled fed microstrip square ring patch antennas and two microstrip slot antennas of the same linear polarization. These two types of antennas are printed on different sides of the substrate to reduce mutual coupling. With a novel isolation structure etched on the ground plane of the FR4 substrate, high port isolation (below dB) and good MIMO performance are achieved. The overall lateral size of the MIMO system is only , and good impedance matching ( dB) is achieved across the operating band for all the antenna elements. Full spherical radiation patterns are measured for the MIMO system, showing similar radiation characteristics, and the gains are above 2.3 dB across the operating band.

A Dual-Band Circularly Polarized Stub Loaded Microstrip Patch Antenna for GPS Applications

Abstract: A single-feed low-profile and easy to fabricate circularly polarized microstrip patch antenna has been developed for GPS applications. For dual frequency operation, four slots are etched near edges of the patch and a crossed slot etched in the center for generating circular polarization. In order to reducing the frequency ratio of two frequency bands of the antenna, the patch is loaded by four short circuit microstrip stubs. The paper reports several simulation results that confirm the desired characteristics of the antenna. Using stub loading, the frequency ratio of two bands of the antenna can be, even, reduced to 1.1.

A Compact Planar MIMO Antenna System of Four Elements With Similar Radiation Characteristics and Isolation Structure

Abstract: A compact planar multiple-input-multiple-output (MIMO) antenna system of four elements with similar radiation characteristics is proposed for the whole 2.4-GHz WLAN band. It consists of two proximity-coupled fed microstrip square ring patch antennas and two lambda/4 microstrip slot antennas of the same linear polarization. These two types of antennas are printed on different sides of the substrate to reduce mutual coupling. With a novel isolation structure etched on the ground plane of the FR4 substrate, high port isolation (below -25 dB) and good MIMO performance are achieved. The overall lateral size of the MIMO system is only 0.64lambda times 0.48A, and good impedance matching (S11 < 10 dB) is achieved across the operating band for all the antenna elements. Full spherical radiation patterns are measured for the MIMO system, showing similar radiation characteristics, and the gains are above 2.3 dB across the operating band.

Miniaturized Dual-Band Hybrid Couplers With Arbitrary Power Division Ratios

Abstract: Branch-line and rat-race couplers are designed to have dual-band operation with arbitrary power division ratios. An elementary two-port is proposed to imitate the 90deg section at the two designated frequencies with different characteristic impedances. The two-port consists of a stepped-impedance section with open stubs attached to its two ends, and its circuit parameters are determined by the transmission line theory. The use of the stepped-impedance sections also leads to circuit miniaturization. By the standard microstrip technology, investigated also includes the realizable power division ratios and circuit bandwidths in the two bands, the upper limit of the ratio of the two designated frequencies and the miniaturization factor of the proposed circuit. Hybrid couplers operating at 2.45/5.2 GHz with various power division ratios are designed, fabricated and tested. Experiment results are compared with the theory and simulation.

Resonator for wireless power transmission

Abstract: Disclosed is a resonator for wireless power transmission used in a mobile device. The resonator includes a substrate, at least one microstrip line, and a magnetic core. The microstrip line is formed on the substrate and is provided at one side thereof with a slit to have an open-loop shape. The magnetic core is formed on the substrate and is disposed on a space defined by the microstrip line to increase coupling strength.

Dual-Feed Dual-Polarized Patch Antenna With Low Cross Polarization and High Isolation

Abstract: In this communication, a dual-feed dual-polarized microstrip antenna with low cross polarization and high isolation is experimentally studied. Two different feed mechanisms are designed to excite a dual orthogonal linearly polarized mode from a single radiating patch. One of the two modes is excited by an aperture-coupled feed, which comprises a compact resonant annular-ring slot and a T-shaped microstrip feedline; while the other is excited by a pair of meandering strips with a 180 $^{\circ}$ phase differences. Both linearly polarized modes are designed to operate at 2400-MHz frequency band, and from the measured results, it is found that the isolation between the two feeding ports is less than 40 dB across a 10-dB input-impedance bandwidth of 14%. In addition, low cross polarization is observed from the radiation patterns of the two modes, especially at the broadside direction. Simulation analyses are also carried out to support the measured results.

Design of Compact Tri-Band Bandpass Filters Using Assembled Resonators

Abstract: A novel approach for designing tri-band bandpass filters with independently controllable center frequencies and improved stopband rejection characteristic is presented in this paper. The assembled resonator constructed by a stepped impedance resonator and a common half-wavelength resonator is employed to obtain tri-band response. The stepped impedance resonator is designed to operate at the first and third passbands and the other resonator is designed to operate at the second passband. Two kinds of filter configurations with cascaded and pseudointerdigital formats are proposed. Based on lossless lumped-element equivalent circuit, it is found that both filter structures can introduce transmission zeros between passbands. To verify the proposed approach, two filters are designed and fabricated, the measured results exhibit tri-band bandpass responses with high selectivity.

Waveguides and transmission lines in gaps between parallel conducting surfaces

Abstract: A new way of realizing microwave devices, such as electromagnetic transmission lines, waveguides and circuits of them, is disclosed, that is advantageous when the frequency is so high that existing transmission lines and waveguides have too large losses or cannot be manufactured cost-effectively with the tolerances required Thus, the new technology is intended to replace coaxial lines, hollow cylindrical waveguides, and microstrip lines and other substrate-bound transmission lines at high frequencies The microwave devices are realized by a narrow gap between two parallel surfaces of conducting material, by using a texture or multilayer structure on one of the surfaces The fields are mainly present inside the gap, and not in the texture or layer structure itself, so the losses are small The microwave device further comprises one or more conducting elements, such as a metal ridge or a groove in one of the two surfaces, or a metal strip located in a multilayer structure between the two surfaces The waves propagate along the conducting elements No metal connections between the two metal surfaces are needed At least one of the surfaces is provided with means to prohibit the waves from propagating in other directions between them than along the ridge, groove or strip At very high frequency the gap waveguides and gap lines may be realized inside an IC package or inside the chip itself

Compact UWB Bandpass Filter With Improved Upper-Stopband Performance

Abstract: In this letter, a novel ultra-wideband (UWB) bandpass filter with compact size and improved upper-stopband performance has been studied and implemented using multiple-mode resonator (MMR). The MMR is formed by attaching three pairs of circular impedance-stepped stubs in shunt to a high impedance microstrip line. By simply adjusting the radius of the circles of the stubs, the resonant modes of the MMR can be roughly allocated within the 3.1-10.6 GHz UWB band while suppressing the spurious harmonics in the upper-stopband. In order to enhance the coupling degree, two interdigital coupled-lines are used in the input and output sides. Thus, a predicted UWB passband is realized. Meanwhile, the insertion loss is higher than 30.0 dB in the upper-stopband from 12.1 to 27.8 GHz. Finally, the filter is successfully designed and fabricated. The EM-simulated and the measured results are presented in this work where excellent agreement between them is obtained.

Miniaturized Microstrip Wilkinson Power Divider With Harmonic Suppression

Abstract: A microstrip Wilkinson power divider with harmonic suppression and size reduction is presented in this letter. The proposed power divider not only effectively reduces its occupied area to 36.5% of the conventional design at 2.65 GHz but also has higher order harmonics suppression. From the measured results, a 29 dB suppression for the third harmonic and a 34 dB suppression for the fifth harmonic are achieved while maintaining the characteristics of a conventional Wilkinson power divider. Based on a 15 dB return-loss criteria, the measured fractional bandwidth is 48%. At an operation frequency of 2.65 GHz, the insertion losses are better than 3.4 dB, the return loss is 27 dB, and the isolation is better than 22 dB.

A Compact Dual-Band Dielectric Resonator Antenna Using a Parasitic Slot

Abstract: A compact dual-band dielectric resonator antenna (DRA) using a parasitic c-slot fed by a microstrip line is proposed. In this configuration, the DR performs the functions of an effective radiator and the feeding structure of the parasitic c-slot in the ground plane. By optimizing the proposed structure parameters, the structure resonates at two different frequencies. One is from the DRA with the broadside patterns and the other from the c-slot with the dipole-like patterns. In order to determine the performance of varying design parameters on bandwidth and resonance frequency, the parametric study is carried out using simulation software High-Frequency Structure Simulator and experimental results. The measured and simulated results show excellent agreement.

Substrate-Integrated Waveguide Ku-Band Cavity-Backed 2 $\,\times\,$ 2 Microstrip Patch Array Antenna

Abstract: A Ku-band cavity-backed microstrip patch 2 x 2 antenna array has been implemented using the substrate-integrated waveguide (SIW) technology-a low-cost multilayer printed circuit board (PCB) process. Cavities are emulated using vias, and the patches are fed using microstrip lines that are centrally fed by a shielded coaxial probe feed line. Simple design guidelines for the cavity, patch, and substrate selection are presented. The array was fabricated, and its measured results agreed very well with theoretical predictions and indicated a relatively high efficiency and wide bandwidth of greater than 70% and 9%, respectively.

A Generalized Dual-Frequency Transformer for Two Arbitrary Complex Frequency-Dependent Impedances

Abstract: The purpose of this letter is to propose a dual-frequency transformer for two arbitrary complex frequency- dependent impedances (ACF-DIs) and present a generalized T-junction power divider (T-JPD) operating at dual-band with arbitrary power-dividing ratios based on the proposed transformer. By the rigorous analysis of transmission line theory, the closed-form design equations for this generalized transformer are obtained. Using the analytical design method, a kind of generalized T-JPD can be designed to operate at two different frequencies with different power-dividing ratios. Furthermore, numerical examples are simulated and a microstrip T-JPD operating at 1 and 2.4 GHz with different power-dividing ratios (1.5 and 2 dB, respectively) is fabricated. Good agreements between the simulated and measured results can be observed.

Novel Broadband Planar Reflectarray With Parasitic Dipoles for Wireless Communication Applications

Abstract: A novel broadband planar reflectarray with parasitic dipoles is presented for wireless communication applications. A unit cell of the microstrip reflectarray consists of a printed main dipole with a pair of parasitic dipoles. The introduction of parasitic dipoles can effectively extend the reflection phase range beyond 360°, which overcomes the problem of an inadequate phase range when using thicker substrates for a wider operational bandwidth. The parasitic dipole reflectarrray (PDR) is applied to a wideband CDMA (WCDMA) system to eliminate blind spots in communication between the base station and mobile users. A practical link budget analysis demonstrates the effectiveness of the proposed planar reflectarray.

Compact Dual-Mode Open Loop Microstrip Resonators and Filters

Abstract: A novel compact microstrip dual-mode resonator and filter are proposed. The characteristics of the dual mode resonator are investigated. It is found that the filter response exhibits a desirable stopband response where the first spurious passband naturally occurs at 3f0. Finally, methods of miniaturizing such resonators and filters are discussed. The proposed structure was able to achieve 60% size reduction.

Applications of Open Split Ring Resonators and Open Complementary Split Ring Resonators to the Synthesis of Artificial Transmission Lines and Microwave Passive Components

Abstract: This paper is focused on the application of open split ring resonators (OSRRs) and their dual counterparts, open complementary split ring resonators (OCSRRs), to the synthesis of composite right/left-handed transmission lines, that is, artificial lines exhibiting backward wave propagation at low frequencies and forward wave propagation at high frequencies. Due to the small dimensions of these resonators, the resulting lines are very compact. Several artificial lines, with different electrical characteristics and topologies, are reported as illustrative examples. It is shown that these artificial lines can be applied to the synthesis of dual-band components and bandpass filters, and two prototype device examples are designed and fabricated in coplanar waveguide technology: a dual-band impedance inverter applied to a dual-band power divider, and an order-3 wide-band bandpass filter. Finally, it is also demonstrated that OSRRs and OCSRRs can be combined for the synthesis of band pass filters in microstrip technology. Since OSRRs and OCSRRs are described by means of series and shunt resonant tanks, respectively, and they are electrically small, their potential to the design of semi lumped planar microwave devices is very high.

Reduction of mutual coupling between closely-packed antenna elements using defected ground structure

Abstract: A simple ground plane structure that can reduce mutual coupling between closely-packed antenna elements is proposed. The structure consists of a dumb-bell-like pattern etched in a single ground plane. It is found that isolation of more than −40 dB can be achieved between two parallel individual planar inverted F antennas (PIFAs) sharing a common ground plane. Comparison of the proposed dumb-bell-like defected ground structure (DGS) with other approaches shows its unique capability of reducing mutual coupling. Influence of the designed DGS on radiation pattern and surface current distribution on the ground plane is also investigated.

Planar Substrate Integrated Waveguide Cavity-Backed Antenna

Abstract: A new cavity-backed antenna compatible with planar technology is designed, manufactured, and measured. The original design consists of a slotted cavity fed by a microstrip line. This allows the implementation of the feeding line and the cavity on a single substrate, compatible with a standard printed circuit board (PCB) or low-temperature cofired ceramic (LTCC) process. The idea is to combine specific slot patterns on the cavity back face such as meandered and edge slots. An example is presented, and the measurements show minimum 10-dB return loss bandwidth of 1.32%, 8.5 dBi gain, and 21 dB front-to-back ratio. The combination of volume cavity, planar feeding, and antenna layout, leads to light weight, easy fabrication, and easy integration with planar circuits.

Focused Microstrip Array Antenna Using a Dolph-Chebyshev Near-Field Design

Abstract: A new concept in designing large array antennas to focus the microwave power in the radiation near-field region is presented A small focused array antenna using microstrip patch elements to achieve the desired sidelobes levels in the Fresnel region based on Dolph-Chebyshev design is implemented This array is built to verify the concept, and then the measured and computed near fields are compared to verify the accuracy of the design Larger arrays are designed by using the knowledge of the mutual admittances between the elements of smaller arrays Several computed examples are presented in order to show some properties of focusing arrays It is shown that the maximum intensity of the electric field along the axial direction is displaced from the focal point towards the antenna aperture This displacement decreases as the aperture size increases

Microstrip square ring antenna for dual-band operation

Abstract: This paper presents a generalized approach to design an electromagnetically coupled microstrip ring antenna for dual-band operation. By widening two opposite sides of a square ring antenna, its fractional bandwidth at the primary resonance mode can be increased significantly so that it may be used for practical applications. By attaching a stub to the inner edge of the side opposite to the feed arm, some of the losses in electrical length caused by widening can be regained. More importantly, this addition also alters the current distribution on the antenna and directs radiations at the second resonant frequency towards boresight. It has also been observed that for the dual frequency configurations studied, the ratio of the resonant frequencies (center dot r(2)center dot center dot r(1)) can range between 1.55 and 2.01. This shows flexibility in designing dual frequency antennas with a desired pair of resonant frequencies.

Elimination of scan blindness with compact defected ground structures in microstrip phased array

Abstract: A compact H -shaped defected ground structure (DGS) is applied to reduce the mutual coupling between array elements and eliminate the scan blindness in a microstrip phased array design. The proposed DGS is inserted between the adjacent E -plane coupled elements in the array to suppress the pronounced surface waves. A two-element array is measured and the results show that a reduction in mutual coupling of 12 dB is obtained between elements at the operation frequency of the array. The scan properties of microstrip phased arrays with and without DGS are studied by the waveguide simulator method. The analysis indicates that the scan blindness of the microstrip phased array can be well eliminated because of the effect of the proposed DGS. Meanwhile, the active patterns of the array centre element in 7times3 element arrays with and without the H -shaped DGS are simulated, and the results agree with those obtained by the waveguide simulator method.