Dual-band Design Research Articles

Design and analysis of a multi-element dual band infrared detector for counter-countermeasure

A dual band multi-element infrared (IR) detector which enables effective target tracking in a complex tactical environment is presented. The photosensitive elements are designed like the stripes of the Lovell optical reticle and arranged close to each other. The thin films of the dual band filter are precisely coated onto an IR transparent substrate, which is then bonded directly onto the surface of photosensitive area with an IR transparent adhesive. The optical system of the detector adopts a spin-scan mode. The filter-detector combination rotates with a mechanical rotor during scanning. The dual band filters temporally encode target location into the incoming radiation signals, and the photosensitive elements then convert the modulated radiation into an electrical signal. The ratio of radiation intensity from two bands can be calculated to distinguish target from IR target-flare mixed signals. Because the pattern of the detector is similar to the Lovell reticle, the detector can also perform spatial filtering to eliminate background noise. In addition, relatively high stability, together with simplicity of the hardware and low cost, indicates that the presented method has a potential application at the field in which precision is not strictly requested.

Dual-Band Compact Planar Antenna for a Low-Cost WLAN USB Dongle

Among the present technologies for WLAN devices, USB dongles still play a noticeable role. One major design challenge regards the antenna, which unavoidably has to comply with a very small volume available and sometimes should also allow multiband operation. In this scope, the present work discusses a dual-band WiFi compact planar IFA-based antenna design for a low-cost USB dongle application. Like most of the related published solutions, the methodology for deriving the present proposition was assisted by the use of an antenna analysis software. A prototype was assembled and tested in order to qualify the radiator design. Practical operation conditions were considered in the tests, such as the influence of the dongle case and the effect of the notebook itself. The results complied with the design constraints, presenting an impedance match quite stable regardless of the stick position alongside a laptop base.

Dual Y-Shaped Monopole Antenna for Dual-Band WLAN/WiMAX Operations

A dual-band design of monopole antenna with two coupled Y-shaped strips for WLAN/WiMAX applications is presented. By the introduction of dual Y-shaped strips, two separated impedance bandwidths of 22.4% (3.28~4.10 GHz) and 19.2% (4.90~5.94 GHz) can be obtained to meet the specifications of the WLAN/WiMAX communication band applications. The proposed antenna is successfully simulated, designed, and measured, demonstrating the matched impedance and good radiation characteristics with an overall dimension of17.7×26×1 mm3.

A Micromachined Dual-Band Orthomode Transducer

In this paper, an orthomode transducer (OMT) for dual-band operation and optimized for stacked micromachined layers implementation is presented. The proposed design avoids the use of septums, irises, pins, or small features and minimizes the number of equal-thickness micromachined layers required. In this way, the micromachining fabrication is simplified, making the proposed design a very attractive candidate for high frequency applications and for low-cost batch production. A W-band dual-band design (one different polarization in each frequency band) with more than 10% fractional bandwidth for each band and 30% separation between bands is presented. In addition, proper routing and layered bends are designed for an optimum standard interfacing with the same orientation of the input/output ports. Two OMTs in a back-to-back configuration are fabricated using a thick SU-8 photo-resist micromachining process. A total of six stacked SU-8 layers, all of them with the same thickness of 635 μm, are used. The experimental results are coherent with the tolerance and misalignment of the process, validating the proposed novel OMT design.

Singly-Fed Dual-Band Circularly Polarized Dielectric Resonator Antenna

This letter presents a new dual-band circularly polarized (CP) dielectric resonator antenna (DRA). The dual-band design utilizes the quasi- TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</sub> and -TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">113</sub> modes of the rectangular DRA, which is coupled by a simple underneath rectangular aperture. Two opposite corners of the DRA are removed at 45 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> to obtain CP fields. A diagonal groove is introduced at the top face of the DRA to facilitate tuning of the DRA. A design guideline of the dual-band CP DRA is given. The reflection coefficient, radiation pattern, axial ratio, and antenna gain of the DRA are simulated and measured, with good agreement between them.

Compact Perturbed Hexagonal Microstrip Antenna for Dual-Band Circular Polarization

A novel dual-band circularly polarized multi-layer microstrip antenna for 3.5-/5.2-/5.8-GHz applications is presented. A stacked-patch configuration is used for the compact dual-band antenna design, and good circular polarization performance is achieved by adjusting the size of truncated corners and inserted slits of the hexagonal patches. The antenna generates circular polarization radiation at 3.49 and 5.18 GHz with good return loss and broadside radiation patterns. The measured peak gains of the antenna are 3.5 and 5.1 dBi at the lower and upper bands, respectively. In addition, the antenna occupies a small radiating area of 15.6 × 16 mm2.

Design and Analysis of a Dual-Band Inverted-F Antenna With Orthogonal Frequency-Controlled Radiation Planes

A dual-band inverted-F antenna design operating at 433/868 MHz ISM bands is reported. The structure is planar, fed by a coplanar waveguide and easily integrated into a PCB. The device has the ability to produce radiation in two different orthogonal planes with respect to the operation frequency. This frequency-controlled radiation property offers a spherical coverage in space. A transmission line model based on the asymmetrical coplanar waveguide is used to analyze the critical parameters of the design and can be used to estimate its performance. Analytical equations are provided confirming the model and the simulations. The design procedure can be used to adjust the structure to the desired operating frequencies and to achieve the required frequency ratio (fH/fL). Measured data from a fabricated prototype show return loss greater than 10 dB at both frequency bands and are compared to simulations. Measured and simulated radiation patterns demonstrate the reconfiguration of the radiation planes with frequency that can be used for more reliable mobile communications.

Dual-Band Wlan Antenna Design by Controlling Higher Order Mode Characteristic

This article presents a new method for designing a dual-band WLAN antenna using the higher order harmonic mode of a monopole antenna, the first-order mode of which operates at the low-frequency band of WLAN (2.4 GHz). After measuring the current distribution in the higher order antenna mode, we added a stub in a location where the electric field is strong. This added stub brought the resonant frequency into the higher WLAN frequency band. Further, the input impedance was controlled by controlling the width of the branch without affecting the low-frequency band of the WLAN (the first-order mode of the monopole antenna). This compact dual-band antenna was designed to be the size of a universal serial bus dongle, and the −10 dB bandwidths are 700 MHz (2.3–3 GHz) at 2 GHz and 1 GHz (4.9–5.9 GHz) at 5 GHz, which cover the full WLAN dual bands. The proposed antenna achieves more than 50% efficiency in WLAN bands. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1897–1902, 2013

Dual-Band Matching Properties of the C-Section All-Pass Network

The all-pass C-section is introduced as a replacement for the classic quarter-wave section in the design of wideband dual-band impedance-matching networks. First, the impedance-matching properties of the all-pass C-section are presented, showing its dual-band behavior. Second, a simple adaptation to dual-band designs of the well-known wideband designs with binomial and Chebyshev responses is introduced. Finally, a dual-band power divider is presented, as a test of the introduced design technique.

Dual-band dual-polarized printed antenna for wireless communication

A novel dual-band dual-polarized antenna design with high isolation and low cross-polarization is presented. An arc-coupled annular ring and a special coaxial-fed slot patch are employed as the radiating elements at lower and upper bands, respectively. Measurements show that the 10-dB impedance bandwidths reach 27.9% (1.66–2.19 GHz) and 18.4% (5.09–6.12 GHz). The port isolation for both bands is better than 30 dB. Moreover, stable and symmetrical radiation patterns at slanted polarizations are achieved, and the measured cross-polarization level is less than dB within the above-mentioned bands.

Design and Analysis of a THz Metamaterial Structure with High Refractive Index at Two Frequencies

The concept of a single frequency band, single high-refractive-index metamaterial has been extended and applied in the design of dual frequency band, dual high-refractive-index metamaterials in the THz regime. The structure design consists of twenty five unit cells with a surface area of 250 um by 250 um and a thickness of 5 um. Each cell has metallic structures embedded in a polyimide substrate. The return loss (S-parameter) analysis shows two strong electric responses at two frequency ranges, and the extracted constitutive parameters suggested high values of simultaneous dielectric constant and permeability at these frequencies. Results retrieved from the S-parameters also show high refractive index values. A first peak refractive index of 61.83 was observed at a resonant frequency of 0.384 THz, and another peak refractive index of 19.2 was observed at the resonant frequency 1.416 THz. Analysis show that higher refractive index at the second resonance frequency band is achievable through redesign of the structures, and modifications could lead to a single structure with multiple frequency, multiple high-refractive-index metamaterials that can be put to practical use.

Dual-mode dual-band bandpass filter design using open-loop resonators

This letter presents a novel dual-band bandpass filter using dual-mode open-loop resonator. Non-degenerate modes of the dual-mode resonator are excited by loading a center-loaded T-shaped stub and its nature is investigated through the even-odd mode analysis. Based on the aforementioned dual-mode resonators, a compact dual-band filter is designed. Results verify that the fabricated filter with the central frequencies of 1.8 and 2.4 GHz and the fractional bandwidth of 8.3 and 12.9% are obtained. Also, there are several transmission zeros located at both sides of each passband. It provides the filter with improved selectivity and stopband suppression. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2370–2372, 2012; View this article online at wileyonlinelibrary.com.. DOI 10.1002/mop.27080

Compact dual-band stubless branch-line coupler

The implementation of microstrip nonuniform transmission lines (MNTLs) for dual-band branch-line coupler design is presented in this study. The proposed structure demonstrates dual-band performance, low insertion loss, and compact size in comparison with other prior proposed dual-band branch-line couplers. The current work fabricates an experimental dual-band branch-line couplers working at 0.9/1.8 GHz. Employing the stubless branches also leads to circuit miniaturization and achieves an overall size reduction up to 64.4%, compared with conventional stub tapped dual-band couplers. Also, stubless dual-band operation of the coupler causes the same phase relation between the two output signals at the two frequency bands. The measured results validate good dual-band performance.

Shunted-Line Stepped-Impedance Resonator

This article provides an extensive review of dual-band bandpass filter designs and discusses the pros and cons of these design methods. The behavior of an SLSIR proposed by the authors shows that two passbands can be generated without using external dual-band impedance transformers. Furthermore, by using the design curves shown in this article, the k and the Qe, which are used for the synthesis of a dual-band bandpass filter, can be accurately calculated. Two examples of dual-band bandpass filters operated at 1.9/5.7 and 2.45/5.7 GHz with different bandwidths was presented to show details of the design technique. The simulation and measurement results shown are in good agreement. The resulting SLSIR dual-band filters using this technique not only provide controllable responses but also have high frequency selectivity and good impedance matching with considerable size reduction. Finally, a performance comparison comparing the technique in this article with previous design methods is listed in Table 3. The design methodology should be useful in dual-band RF transceiver design.

Dual-mode dual-band filter with flexible frequency ratio using degenerate modes of ring resonator

A novel dual-mode dual-band bandpass filter design is introduced by virtue of modified ring resonator. According to qualitative analyses on the field distributions of a conventional ring resonator, T-junctions are utilized instead of ring transmission lines to control the frequency ratio of passbands. Meanwhile, each individual passband is formed using a pair of degenerate modes of the same order resonance. Stepped-impedance perturbations are adopted to split the degenerate modes and control the bandwidths. A design example is given to validate the design approach. The measured results agree well with the performances predicted by analyses.

Requirements, Challenges and Analysis of Alternatives for Wireless Datalinks for Unmanned Aircraft Systems

Two key challenges in the design of datalinks for unmanned aircraft (UAS) systems compared to other wireless links are the long range of distances and speeds that need to be covered. The 960 - 1164 MHz part of the IEEE L band has been identified as a candidate spectrum for future manned and unmanned aircraft datalinks. The amount of spectrum available in the L-Band is not sufficient to support video applications common in UASs and so dual-band designs using both L-Band and C-Band are being considered. For L-Band, two projects funded by EUROCONTROL L-Band Digital Aeronautical Communications Systems 1 and 2 (L-DACS1 and L-DACS2) are often mentioned for use in UAS also. We briefly discuss issues with their use for UAS. We compare the two proposals in terms of their scalability, spectral efficiency, and interference resistance. Then we discuss several issues in UAS datalink design including availability, networking, preemption, and chaining. We also propose ways to mitigate interference with other systems in the L-Band.

Design of Dual Band Patch Antennas for Cellular Communications by Genetic Algorithm Optimization

Designing multiband antennas with low volume becomes of practical interest for mobile telecommunications. This paper presents the designs of five small dual band patch antennas for GSM 1800 (1710-1880MHz) and Bluetooth (2400-2483.5MHz) applications using a genetic algorithm combined with MoM (Method of Moments). A substrate with dielectric constant 3.2 and height 8mm is used for the first two dual band designs. The height is reduced thanks to the optimization process to 6mm in the third design by inserting a shorting pin to the fragmented patch antenna. Further the height is reduced to 4mm in the by inserting two shorting pins. In the final design with three shorting pins, the height is only 3mm. The patch dimensions are similar to that of the conventional rectangular patch for the center frequency of the lowest frequency band but with the advantage of having dual-band operation at the desired bands. Genetic algorithm optimization is used to optimize the patch geometry, feed position and shorting positions. HFSS is used to carry out simulations. The antenna thickness is reduced from 8mm to 3mm by incorporating shorting pins which position is optimized by the genetic algorithm.

Analytical design of novel dual-band cross-coupled substrate integrated waveguide filter

A dual-band substrate integrated waveguide (SIW) filter is presented in this article. The dual-band cross-coupled design procedure is based on the frequency transformation from the normalized frequency domain to the actual frequency domain, which can calculate the coupling coefficients and the external quality factors analytically. The cross-coupled SIW filter has the flexibility to achieve different kinds of filtering characteristics with the same coupling structure. To validate the method, a practical SIW dual-band filter operating at 5.85–5.95 GHz and 6.05–6.15 GHz is designed and fabricated. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1609–1612, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26908

A compact dual-band RF front-end and board design for vehicular platforms

Modern vehicular platforms include several wireless systems that provide navigation, entertainment and road side assistance, among other services. These systems operate at different frequency bands and thus careful system-level design should be followed to minimise the interference between them. In this study, we present a compact dual-band RF front-end module for global positioning system (GPS) operating in the L1-band (1574.42–1576.42 MHz) and satellite digital audio radio system (SDARS) operating in the S-band (2320–2345 MHz). The module provides more than 26 dB of measured gain in both bands and low noise figure values of 0.9 and 1.2 dB in SDARS and GPS bands, respectively. The front-end has interference suppression capability from the advanced mobile phone system and personal communication service cellular bands. The module is designed on a low-cost FR-4 substrate material and occupies a small size of 62 × 29 × 1.3 mm3. It dissipates 235 mW in the SDARS section and 100 mW in the GPS section. Three prototypes have been built to verify a repeatable performance.

Small Antennas: Miniaturization Techniques and Applications

The paper presents research results in the field of small antennas obtained at the Department of Wireless Communications, Faculty of Electrical Engineering and Computing, University of Zagreb. A study comparing the application of several miniaturization techniques on a shorted patch antenna is presented. Single and dual band shorted patch antennas with notches and/or slot are introduced. A PIFA designed for application in mobile GSM terminals is described. The application of stacked shorted patches as array elements for a mobile communication base station as well as for electromagnetic field sensor is presented. The design of single and dual band folded monopoles is described. Prototypes of the presented antennas have been manufactured and their characteristics were verified by measurements.