In this article, a novel compact triple-band monopole antenna for WLAN/WiMAX applications is proposed. The proposed antenna is designed on an FR-4 substrate with thickness of 0.8 mm, relative permittivity of 4.4, and loss tangent of 0.02. It consists of a square ring, an open ended stub, and an inverted T-shaped stub. Three bands covering 2.3-2.76, 3.387-3.73, and 4.97-6.28 GHz are achieved, which cover all the 2.5/3.5/5.5 GHz WiMAX and 2.4/5.2/5.8 GHz WLAN operation bands. Moreover, the presented antenna has a compact size of 24 × 36 mm2. Experimental results show that the proposed antenna gives good gains and has nearly omnidirectional radiation patterns across all the operation bands.
A new method for designing compact Wilkinson power dividers with three order harmonics suppression is presented. The quarter-wavelength transmission line in the traditional Wilkinson power divider is replaced by two pairs of parallel coupled lines with one end connected in series with an open stub. With this structure, the quarter-wavelength line will be shorter and three attenuation poles can be added in the stopband. As a result, this newly proposed structure carries the functions of impedance matching at operating frequency and three orders harmonics suppression. In this study, an example of power divider operating at 1 GHz is designed and fabricated. The measured results show good performance at the operating frequency. In addition, the second, third and fourth harmonics suppressions are 43 dB, 49 dB and 37 dB, respectively, which validates the feasibility of the proposed design.
In this paper, a new approach using quasi-self-complementary antenna (QSCA) to reduce the wideband mutual coupling is proposed and discussed. QSCA element proposed in this paper is composed of a semi-circular radiation patch and a complementary-cut ground plane, which is easy to achieve ultra-wideband operation because its impedance is frequency independent. The proposed compact four-element ultra-wideband (UWB) multiple-input multiple-output (MIMO) array consists of four QSCA elements, and by arranging them anticlockwise, a good impedance matching and high port-to-port isolation (|S11| covers 2.95-12.1 GHz with |S21| = |S31|≤-15 dB, |S41|≤-17.8 dB) can be achieved. Notably, the isolation is obtained without using any other decoupling methods and totally benefits from the asymmetrical radiation property of QSCA. As an example, the proposed four-element UWB MIMO array is fabricated and tested. And the measured radiation pattern, gains and total efficiencies are displayed and show good performances which make it a nice candidate for future UWB diversity applications.
Previous ink characterization results published in the paper are corrected by new characterization measurements from Co ink consisting of the same Co nanoparticles bound together with poly(methyl methacrylate). New measurement result is reported as vol% whereas previous result was reported as wt.%. Correlation 50 vol% = ∼90 wt.%.
Previous ink characterization results published in the paper are corrected by new characterization measurements from Co inks based on same cobalt nanoparticles bound together with poly(methyl methacrylate). New measurements results are reported as vol% whereas previous results were reported as wt.%. Correlations are 30 vol% = ∼80 wt.%, 40 vol% = ∼86 wt.% and 50 vol% = ∼90 wt.%.
Free space path loss modelling is a model used to model path loss propagation for Wireless Local Area Networks. In some cases, the estimation of path loss by the FSL model can be inaccurate as FSL modelling does not take into account the effect of multipath propagation. The International Telecommunication Union Recommendation, ITU-R P.1411-7 provides prediction methods for the planning of short-range outdoor radio communication systems and radio local area networks in the frequency range 300 MHz to 100 GHz. This recommendation further proposes a location variability correction, ρ, which models the standard deviation of field strength due to small scale fading. This paper investigates the feasibility of using the ITU-R P.1141-7 Recommendation to estimate the path loss for 802.11n signals experienced by pedestrians in a suburban environment. Received signal strengths were collected from field experiments, and the measured path loss was compared with estimated path loss values. The results show that for areas with high levels of small scale fading, the ITU-R P.1141-7 was able to estimate the path loss for IEEE 802.11n signals with a higher accuracy of 5-7 dB than the FSL model.
A novel traveling-wave hybrid plasmonic optical antenna is proposed for operation at the standard telecommunication wavelength of 1550 nm and with the frequency bandwidth of more than 16 THz. A highly directive radiation pattern with 15.2 dBi directivity and 82% efficiency is achieved. The developed antenna benefits from high directivity advantage of leaky-wave antennas, and low loss properties and confinement of hybrid plasmonic structures. The designed device can have applications in inter/intera chip optical interconnect, and absorption enhancement of photodetectors, and solar cells.
In this letter, a novel compact dual-band microstrip bandpass filter (BPF) with multiple transmission zeros is proposed using the third-order interdigital structure and dual-mode short stub center-loaded resonator (DSLR) for wideband and WLAN applications. The high impedance feedline for the filter with the folded DSLR can function as the quarter-wavelength resonator (QWR) for the third-order interdigital filter. Meanwhile, the folded DSLR can be adopted without an evident increase of the size of the compact interdigital filter. Three transmission zeros between two passbands and in the lower- and upper-stopbands can be created due to the cross coupling between two high impedance feedlines as well as between the input and output, and the intrinsic characteristic of the DSLR. Further, two inverse QWR coupling short stubs with different size loaded in the 50 Ω feedlines can generate four transmission zeros to improve the isolation and deepen the stopband. Finally, a compact dual-band BPF prototype is designed, and good agreement can be obtained between measured and simulated results.
This work deals with the electromagnetic characterization of the electrical conductivity of anisotropic and weakly conductive materials by using resonant circuits. Experimental results characterizing a carbon fiber reinforced polymer (CFRP) ply are presented.
In this letter, a novel broadband single-layer reflectarray element composed of a circular patch and double circular ring is presented. The element in the reflectarray provides a nearly 360° linear phase range and has rebirth capability. The broadband characteristic of this reflectarray is obtained due to the sub-wavelength of the element space and the combination of two resonators of complementary size on a single layer. Then, a prime-focus 225-element microstrip reflectarray with this phoenix cell has been designed and implemented. The measured gain is 22 dBi with 1 dB drop within 29% bandwidth at the center frequency of 10 GHz.
Original resonant structures for improving efficiency of wireless charging system with the possibility of data exchange are presented. Characteristics of two different dual-mode spiral resonators were obtained by electromagnetic and circuit simulations. Based on these results, an optimum design for highly efficient data and energy transfer was suggested.
A multiband four-antenna system with high isolation for the mobile phone applications is presented in this paper. The four antennas consisting of a main antenna and three auxiliary antennas are located on a 135×65×0.8 mm3 FR4 epoxy board. The main antenna is an improved monopole antenna which can cover LTE700/2300/2500, GSM850/900/1800/1900/UMTS, and 2.4-GHz WLAN bands. Three identical auxiliary antennas with a size of 40×6×0.8 mm3 are located vertically in the sides and bottom of the circuit board, respectively. By adopting three slots in each radiating patch of the auxiliary antennas, they can successfully cover 704-746 MHz and 1880-2690 MHz band with S11 less than -6 dB. The isolation among the four antennas is better than 13 dB. The measured efficiency of the main antenna in the operation band can reach 40%, and the efficiency of auxiliary antennas can reach 25% at upper frequency band and about 10%-20% at 704-746 MHz band.
This letter presents a compact triple-band passband filter with high frequency selectivity. The first and second passbands are formed by a multi-stub loaded resonator. The width of the second passband can be independently adjusted by tuning the coupling strength between the two loaded open stubs. The third passband is implemented using two asymmetrical stepped impedance resonators (SIRs) with a tapped line structure as external coupling form. The asymmetrical SIRs also serve as one part of the external coupling structure of the multi-stub resonator so as to achieve a compact circuit size. Additionally, a source-load coupling is introduced, thus, multiple transmission zeros are generated to improve the frequency selectivity. After a detailed introduction of the operation principle, a triple-band passband filter with centre passband frequencies of 1.5, 2.6 and 3.6 GHz is designed and fabricated. The measured results verify the effectiveness of the proposed filter.
In this paper, a penta-band antenna design using matching network for mobile phone application is proposed. This design is composed of a planar inverted-F antenna (PIFA) and a LC-tank-stacked network. The LC-tank-stacked network consists of two pairs of stacked chip-LC tank, which is parallel with the microstrip line feeding to the antenna. The PIFA works for generating dual bands, and each pair of chip-LC tanks can effectively enhance the lower band and upper band, respectively. According to measured results, the bandwidth can cover 824-960 MHz/1710-2170 MHz band for WWAN application for VSWR = 3:1. The peak antenna gain is better than 0.5 dBi and 3.4 dBi for lower and higher operation band, respectively. And the measured radiation efficiency is about 40-60% and 40-70% lower and higher operation band, respectively.
In this paper, a novel compact tri-band bandpass filter (BPF) with compact circuit size and high passband selectivity has been presented and implemented using multipath-embedded resonator (MER). This filter includes two multipath-embedded stepped impedance resonators (SIRs), connected with stub-coupling at the symmetric plane. By tuning admittance ratio and length ratio of the multipath-embedded resonator, it can be designed at 1.84, 2.45, 3.05 GHz. Through internal edge-coupling and extemal zero-degree feed lines, a tri-band BPF can be achieved with compact circuit size, high passband selectivity and low insertion loss. The measured results validate the full-wave EM simulated results with good agreement.
A novel broadband circularly polarized slot antenna with a rotated slot for bandwidth enhancement is proposed. The antenna has a simple structure, consisting of a microstrip feed line, a substrate, and a rotated rectangular slot with two branches etched on the plane. By appropriately adding the rotated rectangular slot and two branches on the ground-plane, the impedance bandwidth of the antenna is enlarged, and its wide axial-ratio (AR) bandwidth is achieved. Experimental results show the proposed antenna has good right-hand circular polarization (RHCP) characteristics. The measured -10-dB return loss impedance bandwidth and 3 dB axial-ratio bandwidth are 38.8% (1.5 GHz~2.2 GHz) and 25.6% (1.56 GHz~2.02 GHz) at the center frequency of 1.8 GHz.
An analysis of quasi-optical unstable Bessel-Gauss resonator (QOUBGR) at millimeter wavelengths is presented in this paper. The QOUBGR, formed by a conical mirror and a convex mirror, is designed on the basic of quasi-optical theory and techniques. For the purpose of precisely analyzing the designed QOUBGR, a new algorithm known as iterative dyadic Green's functions (IDGF) is proposed, which originates from famous Fox-Li algorithm. The IDGF algorithm can calculate not only two-dimension (2-D) but also three-dimension (3-D) resonating modes in the cavity. Simulation results demonstrate that the designed QOUBGR can steadily support both zero-order and high-order resonant modes that are approximations to Bessel-Gauss beams. These beams will find their promising applications in the MM- and/or quasi-optical imaging and measurement systems.
This paper presents a comparative study of rectangular base desktop shaped broadband patch antenna (Antenna1) and triangular base desktop shaped broadband patch antenna (Antenna2). Apart from base dimensions all parameters of both antennas are constant. The broadband characteristics are achieved by introducing two parasitic ground planes and notches are etched on the radiating patch. Both antennas are simulated, fabricated and tested for obtaining the desired performance. The designed Antenna1 shows bandwidth of 39.97% (4.95 GHz to 7.42 GHz) whereas an improved bandwidth of 49.0% (4.53 GHz to 7.47 GHz) is achieved through Antenna2. Further, gain and radiation pattern of the two antennas are compared and discussed. The effect of inclination angle `α' on Antenna2 characteristics in obtaining the improved bandwidth is also studied. The proposed antennas are simulated, and results are verified experimentally.
This paper presents a data fusion algorithm combining a 24 GHZ radar and a 94.5 GHz radiometer for 3D image. Three trihedral reflectors are tested as multiple targets. Based on a conical scanner, the radar azimuth-range image and radiometric azimuth-elevation image are firstly obtained and preprocessed respectively. Then the common dimension of azimuth is made use of to align two images and synthesize a 3D image, where the positions, ranges and combined intensities of the targets are illustrated. Outdoor tests and experiment results demonstrate the effectiveness of the idea.
A new planar engineered material structure, which has multiple Fano resonances at the terahertz range of frequency, is presented. Starting with a double Fano resonance structure, it is shown that by considering several unit cells as a larger unit cell and creating new asymmetries in the super-cell, we can have five Fano resonances in one structure. Analysis of current distributions at resonance frequencies clarifies the origin of different resonances. We show that all of these resonances come from different arrangement of magnetic dipoles.