http://ieeexplore.ieee.org TOC Alert for Publication# 7727 2012 February 10 10 C1 1680 125 10 C2 C2 35 10 1 2 267 LF/29, where λ_LF is the lowest frequency of the operating band.]]> 10 3 6 789 10 7 10 673 10 11 13 519 2 instead of using expensive ceramics. The WCDMA/WLAN antenna achieves multiband operation with good impedance matching and radiation behavior. Antenna measurements are presented to validate the simulations.]]> 10 14 16 242 10 17 20 199 10 21 24 333 1. Also, a wide bandwidth at f₂ is easily achieved by coupling between the monopole and parasitic radiator. From the measured results, the 10-dB reflection coefficient bandwidth of the proposed antenna covers WiBro (2300-2390 MHz), Bluetooth (2400-2484 MHz), WLAN (2400-2485 and 5150-5850 MHz), WiMAX (2500-2700 MHz), and S-DMB (2605-2655 MHz) bands.]]> 10 25 28 698 10 29 32 340 10 33 36 490 10 37 40 666 r = 3.2), which is used as a substrate for the compact design. Also, the designed antennas have good impedance matching and radiation characteristics for Digital Video Broadcasting-Terrestrial (DVB-T) service of VHF (174-230 MHz) band, Digital Video Broadcasting-Handheld (DVB-H) service of UHF/L (470-862 MHz/1452-1492 MHz) bands and also wireless local area network (WLAN) service of IEEE 802.11b/a (2.4-2.5 GHz/5.15-5.825 GHz) bands. The design methodology and the measurement results of the proposed antenna are presented in detail.]]> 10 41 44 934 10 45 48 438 10 49 52 481 10 53 55 540 10 56 58 588 o) of 1.94 GHz, a -3-dB fractional band- width (FBW) of 5.57%, a gain (G) of 4.87 dBi, a front-to-back ratio (FTBR) of 25.60 dB, and a co-to-cross-polarization ratio of 22.86 dB in the direction of maximum radiation. The integration of the filter and the antenna into just one module leads to a reduction of size and weight in the RF front-end, while the implementation by means of the substrate integrated waveguide technique makes the integration with planar circuits easier.]]> 10 59 62 345 r) is greater than the permittivity (ε_r).]]> 10 63 66 585 10 67 70 895 10 71 74 610 m × 0.44λ_m, where λ_m is the wavelength at the lowest operating frequency. These dimensions are about 20% higher than those of the original CSLA, but with the advantage of providing an extra polarization. This antenna is fabricated with an integrated balun feed and measured. The measurements and the simulations agree well and show good matching over more than two octaves of bandwidth and isolation better than 25 dB between the two polarization ports.]]> 10 75 78 497 10 79 82 711 10 83 86 322 r = 10.02) substrate achieves a reasonable axial-ratio bandwidth. At the operating frequency of 1.575 GHz, the size of the patch is 0.13λ_o × 0.13λ_o, while the ground size is 0.315λ_o × 0.315λ_o and the thickness of the substrate is 0.05λ_o. The measured gain is 4.5 dBi, and axial-ratio bandwidth is 3.2%.]]> 10 87 90 393 x_δ01 mode is introduced. The value of 6 approaches zero for a dielectric with high permittivity. The TE^x_δ01 mode has been explored with the possibility of a radiating mode in the hybrid dielectric-air resonator antenna with good radiation efficiency and broadside pattern. Owing to special electric field distributions, the resonant frequency of the TE^x_δ01 mode is mainly determined by the dimension along the z-axis and relatively stable regardless of changes in length along y-axis. The proposed antenna has an impedance bandwidth of 85 MHz at 3.5 GHz and a gain of about 5.72 dBi. A prototype is fabricated and measured. Measured and simulated results show high accordance.]]> 10 91 94 983 2, including the feed structure. The measured -10-dB reflection coefficients bandwidth of the two modes are 770 MHz (32.1%) and 730 MHz (30.4%) at the operating frequency of 2.4 GHz. In the WLAN band, the ports isolation is better than -21.3 dB. Gains of the two modes are better than 2.9 and 4.1 dBi. Radiation patterns are measured and compared to simulation results. The proposed antenna has the advantages of compact dimension, wide bandwidth, good ports isolation, and low cross polarization.]]> 10 95 98 1191 10 99 102 538 10 103 106 523 11| <; -10-dB bandwidth with >;1.2 dB gain using a λ₀/9.8 × λ₀/9.8 × λ₀/39.4 footprint. It is shown that the antenna has 49% smaller footprint area than a standard patch and exhibits the same bandwidth performance at the expense of lower gain. The second antenna is fabricated on a reduced-size substrate comparable to its footprint size. This antenna still exhibits the same bandwidth performance as the standard patch. The third antenna is on a 250-mil-thick substrate and exhibits 14.7% bandwidth and 4.34 dB gain with λ₀/9.8 × λ₀/9.8 × λ₀/19.7 footprint.]]> 10 107 110 578 10 111 114 732 10 115 118 753 10 119 122 471 10 123 126 463 10 127 130 691 10 131 134 279 10 135 138 230 10 139 142 315 10 143 146 300 10 147 150 393 10 151 154 494 10 155 158 756 10 159 162 893 10 163 166 212 3. This antenna has the advantages of simple configuration, low profile, compactness, and low fabrication cost. Microwave experiments and numerical simulations are performed to demonstrate its functionalities.]]> 10 167 169 643 10 170 173 570 o surface-wave mode that is launched by an array of slots in the ground plane. The leaky-wave attenuation and phase constants are derived using a simple but accurate field perturbation approach. The radiation power, directivity, and beam patterns are also deduced. Numerical results show that, depending on the screen period and the substrate height, there is an optimum frequency range for maximum radiative power. In addition, calculated results are also in agreement with simulations and measurements for some recently designed and fabricated structures.]]> 10 174 178 601 1 linear antenna arrays where each linear antenna array consists of N₂ receiving antennas. In each cycle, the receiving antennas on each linear antenna array are switched to the single receiving channel in turn from the first antenna to the N₂th antenna. An accurate and detailed system model for the radar system is addressed. The Cramer-Rao lower bound (CRLB) analysis on the accuracy of estimating the azimuth angle, elevation angle, velocity, and range using the radar system is presented.]]> 10 179 182 293 10 183 186 306 10 187 190 560 10 191 194 689 11 of the antenna in frequency domain is less than -10 dB in the band of 220 MHz-6 GHz, and it is also verified that the resistors mainly have influence on the antenna's S₁₁ below 1 GHz. The measured reflected pulses show that there are only two reflecting points, and the reflection is weak. The simulated and measured antenna gains at boresight show little variations with loading resistors of different values, and this means that the resistive loadings do not affect the gain characteristics of the antenna. The antenna's transmission re- sponse in time domain is also tested, and its application in GPR detection of a buried target is validated by experiments.]]> 10 195 198 619 10 199 202 513 10 203 206 722 10 207 210 909 10 211 214 374 10 215 218 573 10 219 222 618 10 223 226 484 2, or about 0.15λ × 0.25λ at 4.2 GHz, while showing the band-rejection performance in the frequency band of 5.05-5.95 GHz.]]> 10 227 230 630 10 231 234 505 10 235 238 703 3 is demonstrated for special small-size and pure near-field industry application requirement. The measured reading range is 37 mm (with Impinj UHF button) without reading nulls. The measured bandwidth is 220 MHz (750-970 MHz) under the condition of voltage standing wave ratio (VSWR) less than 1.5, which covers the Europe and FFC standards and agrees well with the simulated results. In addition, the antenna has a low far-field gain less than -20 dBi, which can be applied in pure near-field RFID systems.]]> 10 239 242 753 10 243 246 372 10 247 250 678 10 251 254 754 2), almost stable radiation pattern, and reflection coefficient of lower than -10 dB across the entire passband. A prototype of the proposed antenna is fabricated, and the measured results are shown to be in good agreement with the simulated results.]]> 10 255 258 565 10 259 261 597 10 262 265 508 10 266 269 537 10 270 273 136 11 properties is completely presented and discussed.]]> 10 274 277 1044 10 278 281 635 h and a copolarized horizontal receiving loop located at a height of z ≥ 0, coupling between the dipoles was measured for distances up to 50 m along a direction perpendicular to the surface normal axes of the loops. Inverting the theoretical expressions to estimate the distance from measured field values resulted in peak and rms distance estimation errors of 23.01 and 11.74 cm, respectively, for distances between 1.3 and 34.2 m. Received signals were not strongly affected by the proximity of a group of people even when the line of sight was obstructed.]]> 10 282 285 456 10 286 289 514 10 290 293 744 10 294 297 155 10 298 301 757 10 302 305 777 2.]]> 10 306 309 307 0 from element center to center (side by side of 1.6 mm ≈ 0.031λ₀) when the ground plane size is 0.85λ₀ × 0.55λ₀. Along with this letter, several prototypes were fabricated, and their performances measured to validate the obtained IE3D moment method-based simulation results.]]> 10 310 313 297 10 314 317 504 ° linear polarization (LP) is described. Sixteen radiating slots, tilted at an angle of 45^°, are separated by one-half guided wavelength due to use of the alternating inductive and capacitive load slot pairs. These alternating reactance slot pairs allow this novel antenna to achieve impedance matching, uniform field excitation, and suppression of grating lobes simultaneously. The antenna is designed and fabricated using substrate integrated waveguide (SIW) technology to overcome the drawbacks associated with conventional metallic waveguide antennas. The measured impedance bandwidth, maximum gain, and sidelobe levels are 2.7%, 15.64 dBi, and 15.36 dB, respectively, at the design frequency. The measured data are in agreement with the theoretical calculations and demonstrate the validity of the design technique for the proposed antenna structure.]]> 10 318 321 1041 10 322 325 1016 10 326 329 818 2 was comparable to that of antenna-matching sensors. Total RF insertion losses due to the compared proximity sensors and loss compensation systems were 0.4 and 0.55 dB, respectively, across the 900- and 1900-MHz frequency bands.]]> 10 330 333 250 10 334 337 602 10 338 341 494 10 342 345 199 10 346 349 803 10 350 353 198 10 354 357 1378 L-band satellite communication system: Inmarsat application (downlink: 1525-1559 MHz, uplink: 1626.5-1660.5 MHz). The proposed antenna was carefully investigated and discussed. The measured results show that the impedance bandwidth for return loss below -10 dB is about 170 MHz, and the half-power beamwidth (HPBW) can be up to 110°. The antenna can be used in the high latitudes thanks to its wide HPBW.]]> 10 358 360 533 10 361 364 380 10 365 368 1349 3 operates over the frequency band between 2.67 and 13 GHz (4.74:1, 132%) for VSWR <; 2, exhibiting a 32.2% (4.9-6.9 GHz, 1.5:1) circular polarization (CP) bandwidth. Throughout this letter, the improvement process of the axial ratio (AR) and S\ properties are presented and discussed in detail.]]> 10 369 372 1065 10 373 376 1026 2.]]> 10 377 380 307 10 381 384 244 10 385 388 420 10 389 392 438 10 393 395 473 10 396 398 173 1a → 0 where k₁ is the wavenumber in the matrix and α is the particle radius, new analytical formulas are obtained for k₁a <; π/10, from which the DNG bandwidth can be easily computed. As an example, a contour map of DNG bandwidth for a wide range of values of particle permittivity and permeability is plotted for particle volume fraction f = 0.3. From the analytical formulas, it is shown that the maximum achievable DNG band width for a simple cubic lattice of spheres with particle volume fraction f = 0.3 is 7.4%, when the particle permittivity and permeability are both approximately 14 times greater than those of the matrix.]]> 10 399 402 209 2.]]> 10 403 406 738 10 407 410 289 10 411 414 279 10 415 418 471 z integration is utilized to get a closed-form solution. The guided modes are accounted for with a pole-searching algorithm. Both one-branch-cut and two-branch-cut cases are studied. Several numerical results are presented to validate this method.]]> 10 419 422 377 10 423 426 734 11 mode and generates the higher-order TE₂₁ mode in order to reduce the cross polarization of offset reflectors. To excite the second mode, two blocks and a small discontinuity step are used. These blocks are tangent to the aperture of the second waveguide, as opposed to the traditional case where they are usually located right at the discontinuity step, which results in high reflections. An analytic model is then de ployed to extract the mode content factor along with the field tapers of each mode in the principal planes. Other than far-field radiation patterns, emphasis is placed on the scattering parameters of the antenna, and they are compared to the ones for the same antenna with no blocks as well as the traditional case when the blocks are placed right at the discontinuity of the stepped waveguide. It is shown that the proposed feed provides a good impedance match, over a wide frequency band, similar to its counterpart for the single-mode antenna with no blocks. To verify the concept, a prototype antenna is fabricated and tested. There is an excellent agreement between the simulated and measured results.]]> 10 427 430 673 10 431 434 443 3 is constructed and tested. The simulated and measured results show that the antenna has the active reflection coefficient less than -9.6 dB in the band 2.6-6 GHz. The radiation performance of the antenna is good over the whole frequency band.]]> 10 435 437 658 10 438 441 403 10 442 445 263 10 446 449 314 max, and a radiation pattern of omnidirectivity. The designed antenna has great potential for its flush-mount capability.]]> 10 450 453 617 10 454 457 182 02 mode with a vertical linear polarization for ITS application, which considerably increases the impedance bandwidth. Very good consistency between the measurement and simulation for the return loss and radiation patterns is achieved.]]> 10 458 461 695 10 462 465 610 10 466 468 409 10 469 471 190 10 472 475 463 10 476 479 208 10 480 483 711 3 and operates over the frequency band between 2.6 and 11.12 GHz for VSWR <; 2. Using multifractal concept in modified Pythagorean tree fractal antenna design makes monopole antennas flexible in terms of controlling resonances and bandwidth. In this letter, the improvement process of the impedance bandwidth has been presented and discussed.]]> 10 484 487 999 10 488 491 455 10 492 495 516 10 496 499 452 10 500 502 213 10 503 506 164 10 507 509 1097 3 solar antenna 3-D structure operating around 2.4 GHz demonstrates the potential of the presented configuration for the implementation of autonomous integrated wireless sensors nodes.]]> 10 510 513 337 10 514 516 375 10 517 519 602 10 520 523 477 10 524 527 608 10 528 531 352 10 532 535 264 10 536 539 376 10 540 543 705 10 544 547 1349 10 548 551 871 S₁₁ better than - 15 dB at the frequency of interest. In addition, the radiation pattern of both antennas is influenced. This can be seen as an advantage or a disadvantage, depending on the application.]]> 10 552 555 516 Q-factors of two coupled thin dipole antennas with sinusoidal current distribution. The approach is based on novel rigorous equations for radiated power and stored energies recently derived by Vandenbosch. First, we study the validity of the used thin-wire approximation with a reduced kernel. Good agreement between the assumed sinusoidal current distribution and the real cylindrical antenna modeled with the full-wave method of moments (MoM) is observed. Then, radiation Q-factors are evaluated for half-wave side-by-side coupled dipole antennas with different feeding configurations. It is found that every such combination of studied coupled dipoles presents minimum Q for specific feeding arrangement and separation distance.]]> 10 556 560 466 Y-power splitter are performed to verify the implementation with the PML. The results show that with the proposed method, CPU time savings can be up to 50% of that of a conventional ADI-FDTD.]]> 10 561 564 520 2, high efficiency, and high-gain advantages.]]> 10 565 568 593 10 569 572 610 10 573 576 369 LC (ELC) resonators with broadband tunability of the resonance frequency is presented in this letter. An ELC resonator is typically composed of inductive loops and a capacitive gap, resonant at a wavelength much larger than its physical dimension. Here, the original resonator is modified to accommodate a varactor and its accompanying dc bias enabling resonance tunability. The wideband operation can be achieved through strategic placement of the varactor. The robustness of the response for a large array containing hundreds of the varactor-loaded resonators is considered via a sensitivity analysis. The numerical and experimental results show that the fabricated array possesses a wide tuning range of nearly 32% with no significant resonance broadening, despite the tolerance in varactor characteristics.]]> 10 577 580 482 3) and four antennas mounted on a typical body-worn vest to achieve an omnidirectional pattern. Each antenna element is carefully designed for body-worn mounting onto fitted vests and can operate at UHF frequencies with reasonable on-body gain. Radiation patterns are calculated and validated via measurements. Performance is also evaluated in an indoor environment for several realistic human activities. Comparison to a simple whip monopole antenna is also provided.]]> 10 581 583 481 10 584 587 623 10 588 591 553 B₁ field produced by a transmission-line resonator element for high-field magnetic resonance systems. The method calculates the surface currents on a homogeneous phantom with triangular patches with the Rao-Wilton-Glisson (RWG) basis functions, and the tetrahedra with the Schaubert-Wilton-Glisson (SWG) basis functions are used to calculate the resonator element field. The transmission-line resonator element is excited at its resonant frequency and the equivalent surface current distribution over the phantom are obtained, and then the internal fields in the phantom are calculated for the 9.4-T MRI system. This integral equation method provides much faster B₁ field results than the corresponding finite-difference time domain (FDTD) approach. A field localization method by adjusting phase excitations is also discussed.]]> 10 592 595 513 10 596 598 156 10 599 602 172 0.5Mn_0.2Co_0.07Fe_2.23O₄ ferrite substrate (14 × 7 × 3 mm³) and characterized for antenna performance. Measured return loss and isolation were -26 and -16.4 dB at 720 MHz, respectively. Correlation coefficient calculated from experimental S-parameters (S₁₁, S₂₂, S₁₂, and S₂₁) was less than 0.02 in the LTE band. Three-dimensional peak gain at 746 MHz was measured to be -8.83 dBi for antenna 1 and -8.32 dBi for antenna 2. These low antenna gains are attributed to high magnetic loss of ferrite substrate. Performance simulation suggests that antenna gain can be further improved up to -3.14 dBi with the use of low-loss ferrite.]]> 10 603 606 518 10 607 610 769 10 611 614 1019 10 615 618 853 10 619 622 330 10 623 626 327 L_sub) × 24 (W_sub) × 1.6 (H) mm³. The antenna structure is fabricated and tested. Measured S₁₁ is ≤ -10 dB over 2.3-2.5 and 3.1-12 GHz. The antenna shows acceptable gain flatness with nearly omnidirectional radiation patterns over both Bluetooth and UWB bands.]]> 10 627 630 721 10 631 634 299 L-band telemetry link antenna for meteorological stratospheric balloon payloads, but the achieved results can be extended to any quadrifilar helical antenna with shaped pattern. Size reduction close to 50% is reached while preserving major radiation pattern characteristics and good axial-ratio performance over a wide angular range.]]> 10 635 638 249 10 639 642 175 10 643 646 861 10 647 650 592 3. The simulated and measured performance of the antenna confirms its multiband operation and omnidirectional radiation pattern.]]> 10 651 654 718 10 655 657 243 10 658 661 526 10 662 665 401 10 666 669 328 10 670 673 206 10 674 677 558 10 678 681 345 10 682 685 691 10 686 689 268 10 690 692 346 10 693 696 553 10 697 700 844 10 701 704 804 r = 6.4), whereas the lens has been realized on a high-dielectric-constant superstrate (CT765, ε_r = 68.7 ). The two (substrate and superstrate) are integrated through four corner posts to realize the required air gap (focal distance). The fractal array alone provides a measured gain of 8.9 dBi. Simulations predict that integration of this array with the lens increases the gain by 6 dB. Measurements reveal that the design is susceptible to LTCC fabrication tolerances. In addition to high gain, the SoP provides a bandwidth of 8%. The high performance and compact size (24 × 24 × 4.8 mm³ ) of the design makes it highly suitable for emerging wireless applications such as automotive radar front end.]]> 10 705 708 548 10 709 712 872 10 713 716 926 3. The proposed cavity antenna is realized by making two adjacent side walls of a rectangular dielectric-filled resonant cavity open as radiating ports. The achievable frequency ratio changes from 1.2 to 2.2 with different aspect ratios. With a varactor diode installed at the front open port, the dual frequency bands can be tuned over a wide range. When the applied reverse biasing voltage varies from 3 to 13 V, the realized |S₁₁| <; -6 dB impedance bandwidth is 420 MHz (12.5%) and 960 MHz (20.5%) for the low band and the high band, respectively. The designed antenna occupies no area on a circuit board, and a 0.5-mm-thin volume inside a device cover is enough for installation. The dual bands can be scaled to other desired bands within the frequency ratio range.]]> 10 717 720 1047 10 721 725 705 10 726 729 830 10 730 733 756 10 734 737 771 3 in dimension. Solder bump flip-chip technology is used to attach the AiP to the RFIC for system-level assembly. The assembled package is evaluated using a custom-designed near-field measurement setup. EM simulations and measurements confirm the presented AiP features more than 9 GHz bandwidth, 45° beam-steering ranges in both E- and H-planes, and more than 14.5 dBi gain at boresight.]]> 10 738 741 890 10 742 745 791 10 746 747 414 10 748 751 658 10 752 755 669 10 756 759 769 10 760 763 689 10 764 767 718 10 768 771 539 10 772 775 1122 10 776 779 686 10 780 783 706 10 784 787 614 10 788 791 933 10 792 795 755 10 796 799 721 0, where λ₀ is the minimum operating wavelength and operates over 148% relative bandwidth. The antenna is based on the principle of top-loading of coupled sectorial loop antenna (CSLA). Introducing a series capacitive gap in the top-loading plate and the CSLA fins allows for achieving ultrawideband operation and very low antenna height simultaneously. The proposed structure is also relatively easy and cost-effective to fabricate using standard printed circuit board (PCB) fabrication technology. A parametric study is presented to show the effect of the different dimensions on the antenna performance. A prototype antenna is fabricated and measured. The measurements and simulation results show good agreement and indicate that a VSWR <; 2 over 0.9-6 GHz can be accomplished. It is also shown that the radiation pattern has omnidirectional characteristics over more than two octaves.]]> 10 800 803 624 10 804 807 1384 H and base station antenna relative height h, which are not well-covered by existing large-scale models. The path loss exponents are investigated, based on which the influence of viaduct on propagation is discussed. The fading depth up to 15.96 dB and the Ricean K -factor with mean value of 3.79 dB are obtained.]]> 10 808 812 735 10 813 816 1168 r=3.2) with a limited volume, i.e., 7×11×46 mm³. The design methods and the measured results of the proposed antenna are presented in detail.]]> 10 817 819 855 10 820 823 938 10 824 826 522 2 (0.56 λ₀ × 0.28 λ₀ at 140 GHz).]]> 10 827 830 729 10 831 834 726 10 835 838 700 10 839 842 601 S₁₁| <; -10 dB. The | S₁₁| response of the newly proposed antenna shows an additional resonance compared to its cylindrical ring counterpart without the step, resulting in at least 10% larger impedance bandwidth.]]> 10 843 845 654 10 846 849 1073 3, while maintaining the ultrawideband (UWB) performance.]]> 10 850 853 753 2. It is also promising to bend the antenna into an L shape or meander line to reduce its volume occupied inside the mobile handsets. Good radiation characteristics, gain, and radiation efficiency are obtained over these six operating bands.]]> 10 854 857 848 10 858 861 642 0 (edge-to-edge distance) and 0.27 λ₀ (center-to-center distance) can be obtained. Measured S₂₁ of the array in the first and second designs of the FSRRs are about -56 and -45 dB, respectively. The features including very small occupied area, high performance, and noncomplex structure make the proposed FSRRs more useful for various related applications.]]> 10 862 865 801 z-dependence by kz, can be solved by compact 2-D FDTD method. Moreover, the perfect matched layer (PML), corresponding to the proposed FDTD algorithm, is also presented for the simulation of open system. Three representative examples-cylindrical, ring, and asymmetric parallel-plate resonators-are analyzed to verify the proposed compact 2-D FDTD method.]]> 10 866 868 660 0δ0 modes ( 0 <; δ <; 1, 1 <; δ <; 2, 2 <; δ <; 3, or 3 <; δ <; 4, etc). Here, we have shown only the dual-band results. Successful design of triple- or tetraband antenna is also possible by using our proposed idea. Using unconventional TM_0δ0 mode (0 <; δ <; 1), it has also been shown that miniaturization of a rectangular patch antenna may be only possible with μ -negative (MNG) metamaterial.]]> 10 869 872 1017 10 873 875 1003 10 876 879 883 RLC boundary condition, and the experimental results show that with this model, the simulation can provide an accurate prediction of the antenna radiation performance. The measurement results show that the proposed monopole antenna has a VSWR 2:1 bandwidth over 2.41-2.49 and 5.2-5.6 GHz with omnidirectional radiation patterns. The simulation results suggest that the proposed antenna has a directivity around 1.5 dB at both bands with relatively high radiation efficiency. The antenna is designed and optimized by using Ansoft HFSS.]]> 10 880 883 592 10 884 887 813 10 888 891 881 10 892 895 572 10 896 899 473 10 900 903 845 10 904 906 366 ° and radiates in circular polarization. It consists of a polarizing FSS (used to ensure the polarization conversion) and a corrugated ground plane (designed to guarantee the resonance conditions for both incident orthogonal linear polarizations). A compact shielded FP antenna with an aperture of 1.62 λ₀ is optimized and fabricated in S -band to validate the concept at 2.5 GHz. A 3-dB axial-ratio bandwidth of about 1.9% is achieved with an antenna height of only 0.8 λ₀. The experimental results are in good agreement with the simulations. This antenna configuration is attractive for narrowband applications, like the space ones in C- or S-bands.]]> 10 907 910 1119 2. It is also promising to bend the antenna into a E shape, inverted-T shape and meander line to reduce its volume occupied. Details of the antenna design and experimental results are presented and discussed.]]> 10 911 914 899 10 915 918 807 R⁴ path loss of previous interleaved architectures. Retrodirectivity as well as null steering is reported at 2.4 GHz.]]> 10 919 922 466 10 923 926 613 10 927 930 727 10 931 934 784 S₁₁ | values, radiation efficiencies and patterns, and Q-ratios are provided. For the low, 0-dBm input power level, the measured rectifying efficiencies of the larger (ka = 0.808) and 25% smaller (ka = 0.604) version are, respectively, 78.0% at 1.5754 GHz and 67.9% at 1.55 GHz.]]> 10 935 938 760 S₂₁ is less than - 18 dB within the - 6-dB impedance bandwidth. The average measured total efficiency at the aforementioned bandwidth is - 0.95 dB. The measured radiation patterns are presented at 2 and 4 GHz with orthogonal polarizations. Finally, the measured envelope correlation and effective diversity gain (EDG) as a function of frequency are presented, with a maximum correlation less than 0.01 and EDG better than 8.0 dB.]]> 10 939 942 1386 10 943 946 1048 10 947 950 536 10 951 954 1297 10 955 958 816 3. The antenna is fabricated and tested providing broadband impedance matching, appropriate gain, and stable radiation pattern.]]> 10 959 962 978 10 963 966 668 10 967 970 836 10 971 974 388 10 975 978 1009 10 979 982 733 10 983 986 584 10 987 990 760 10 991 994 392 10 995 998 675 10 999 1002 733 10 1003 1005 623 10 1006 1009 590 10 1010 1014 1388 S-band around 2300 MHz. The proposed structure consists of a slot-loaded patch antenna printed over an optimized metamaterial-inspired reactive impedance substrate (RIS). We demonstrate, step by step, the main role of each antenna element by comparing numerically and experimentally the performance of various antenna configurations: antenna over a single- or dual-layer substrate, standard patch or slot-loaded patch, antenna with or without RIS. The final optimized structure exhibits an axial-ratio bandwidth of about 15% and an impedance bandwidth better than 11%, which is much wider than the conventional printed antenna on the same materials.]]> 10 1015 1018 714 n independent Rayleigh random variables is proposed. The approximation is based on a transformed Nakagami-m distribution. Unlike the existing exact density function in the literature, the new approximation is compact and only employs simple functions that are very easy to calculate and to manipulate. New maximum likelihood estimators for the distribution parameters are also derived that are otherwise impossible using the existing exact density function. A new estimator using the logarithm of the sample and a new estimator without knowledge of the number of variables are also developed. Numerical results show that the new approximation has very high accuracy in most cases considered. Numerical results also show that the new estimators using maximum likelihood and sample logarithm outperform the existing estimators.]]> 10 1019 1022 808 10 1023 1026 701 3 (L×W ×H). It is composed of a series of branches, properly dimensioned and separated to generate the required resonances. A prototype has been realized with a 0.4-mm-thick aluminum foil, properly cut and folded. Results are shown in terms of reflection coefficient, radiation patterns, and gain. The antenna shows a reflection coefficient less then -6 and -10 dB, and a gain between 2.7 and 4.8 dBi and approximately equal to 3.7 dBi, in the DVB-T and WiMAX bands, respectively.]]> 10 1027 1030 778 0 at 2.5 GHz, which results in a strong mutual coupling between antenna ports. A reconfigurable DMN is proposed to reduce the mutual coupling when the array frequency is switched. Measured results show that the use of the DMN realizes a matched (S₁₁ ≤ -10 dB) and decoupled (S₂₁ ≤ -20 dB) bandwidth of 150 and 160 MHz in the lower and higher bands, respectively. In addition, compared to the strongly coupled array, at least 9% antenna total efficiency improvement is measured over a 125-MHz bandwidth in both the lower and the higher bands. The effect of the ohmic loss in the DMN on the antenna correlation is also investigated.]]> 10 1031 1034 849 10 1035 1038 698 3. It can cover the WLAN 2.4- and 5.8-GHz bands. The measured isolation values (S21) are lower than - 25 and - 20 dB at the 2.45- and 5.8-GHz bands, respectively. The key design parameters are presented, and the parametric study is performed.]]> 10 1039 1042 1025 10 1043 1046 697 10 1047 1050 796 10 1051 1054 756 10 1055 1058 901 10 1059 1062 658 10 1063 1067 574 10 1068 1071 1018 10 1072 1075 718 10 1076 1080 1369 10 1081 1084 755 10 1085 1087 585 10 1088 1091 490 3 (0.36λ₀ × 0.054λ₀ × 0.036λ₀) cavity of the metallic cover. The -6-dB bandwidth of 2.62-2.81 GHz (7%) is achieved by combining multiple narrow bands from different resonant elements. A prototype of the proposed antenna is designed and measured to validate the design method. The obtained results including reflection coefficient, radiation pattern, and gain are presented and agree well with the simulation results.]]> 10 1092 1095 814 10 1096 1099 606 z-field over a broad antenna aperture to identify the various items with stable reading performance. To obtain a strong near H_z-field, two coupled patches are employed along with a microstrip-line feed, resulting in average H_z of -15 dBA/m on antenna aperture (30 × 30 × 10 cm³). We also measured the reading range, and it confirmed that the proposed antenna is suitable for a commercial RFID smart-shelf application.]]> 10 1100 1103 880 r/a) ratio of the Koch fractal patterns larger than 0.5 in the whole structure. In the passband region, an improved flat response is obtained by tapering the dimensions of the Koch fractal patterns etched in the ground plane, together with the width of the microstrip line, with a Kaiser distribution that also modulates the periodicity of the fractals. A major consequence of this modulation of the periodicity of the pattern is that this structure is much more compact than a uniform conventional one.]]> 10 1104 1107 1171 10 1108 1111 675 10 1112 1115 731 2.]]> 10 1116 1119 760 10 1120 1123 763 10 1124 1126 502 10 1127 1130 817 S₁₁ | <; - 10 dB and has a gain of 2.41 dBi.]]> 10 1131 1134 863 L)×16 (W)×6 (H) mm³ to be easily embedded inside a handheld reader device as an internal antenna. By properly designing a thin slot and a shorting wall, strong and uniform electric field distribution surrounding the near-zone region can be obtained with the antenna. This design can not only achieve an operating band of 2.38-2.55 GHz, but also generate large capacitive coupling effect to significantly enhance the near-field performance for actual application. Experiments exhibit that the proposed patch antenna may well function as a handheld reader antenna to detect the dipole-like tags through capacitive coupling for RFID near-field operation.]]> 10 1135 1138 804 10 1139 1142 1161 °), hence degrades the radar performance further.]]> 10 1143 1146 860 10 1147 1150 778 10 1151 1153 599 0 × 0.047 λ₀ and the antenna is placed over a 0.237 λ₀ × 0.111 λ₀ CPW ground plane (λ₀ being the wavelength in vacuum).]]> 10 1154 1157 595 10 1158 1161 714 3, the proposed antenna operates in heptaband, including GSM850, GSM900, GPS, DCS, PCS, UMTS, and WLAN, with the return loss lower than 6 dB. The efficiency and gain with the p-i-n diodes with their bias circuit are also measured and analyzed.]]> 10 1162 1165 894 10 1166 1169 1037 10 and TE₁₀ modes. By using the proposed method, the transmission characteristics of the MIMO and the mutual coupling effect at the antenna array can be easily calculated. In addition, the capacity of the MIMO can also be calculated by using the analysis results.]]> 10 1170 1173 1036 10 1174 1177 671 2 and provides the impedance bandwidth of more than 128% between 3.1 and 14 GHz for VSWR <; 2, with notch frequency band at 5.13-6.1 GHz.]]> 10 1178 1181 875 S₁₁ <; -10 dB) of 86% and a 3-dB AR bandwidth of 50%, respectively.]]> 10 1182 1185 1011 2, which is much smaller than most of the current wideband unidirectional antennas. Experimental and simulated results are shown and discussed for practical applications.]]> 10 1186 1189 969 2. The experiment shows that the proposed antenna achieves good impedance matching constant gain, stable radiation patterns over an operating bandwidth of 3-11.2 GHz (115.5%) that covers the entire UWB. The nearly stable radiation pattern with a maximum gain of 5.4 dBi makes the proposed antenna suitable for being used in UWB communication applications.]]> 10 1190 1193 724 10 1194 1196 416 10 1197 1200 1004 10 1201 1204 507 10 1205 1207 1199 3 and built on the printed circuit board. Simulation and measurements are conducted, and both results have proven to be in good agreement.]]> 10 1208 1211 823 2.]]> 10 1212 1215 582 QZE(ω) quality factors of an electrically small antenna were derived by using an equivalent circuit of the antenna. The quality factors complying with the lower bound on the quality factor Q_lb(ω) were defined by means of magnitudes of frequency derivatives of reactance of resonant and antiresonant subcircuits to provide their additivity in the vicinity of an antiresonant frequency ω_a. The quality factor QZE(ω) was used to approximate the conductance bandwidth of an antenna with overlapped resonances. The quality factors at the maximums of the bands of conductance and return loss Q_ZE(ω_1,2) were utilized to calculate the composite quality factor of the antenna Q_ZEc(ω_a) >; Q_lb(ω).]]> 10 1216 1219 1025 10 1220 1223 491 10 1224 1227 999 yz -plane (θ = 0° , 30° , and 331° , respectively), and the overall HPBW is 115°. The measured peak gains are 6.11-6.69 dBi.]]> 10 1228 1231 1000 10 1232 1235 755 10 1236 1238 729 10 1239 1242 1006 10 1243 1246 678 10 1247 1250 630 10 1251 1254 588 10 1255 1258 959 10 1259 1262 801 10 1263 1266 751 10 1267 1269 717 10 1270 1273 869 10 1274 1277 943 10 1278 1281 615 10 1282 1285 531 10 1286 1289 1086 10 1290 1294 1417 10 1295 1298 665 ° and 30 ^°, respectively.]]> 10 1299 1301 499 10 1302 1304 657 10 1305 1308 622 10 1309 1312 908 10 1313 1316 823 0 (λ₀ is the free-space wavelength at the operating frequency), approximately equal directivity can be achieved, compared to an ideal conventional array with a half-element spacing (0.835λ₀) and an identical total size.]]> 10 1317 1320 805 10 1321 1324 538 10 1325 1328 720 10 1329 1332 837 10 1333 1336 1350 10 1337 1340 501 10 1341 1344 770 10 1345 1348 516 ° to 360^° and adaptive beamforming is presented. Multiple radiation patterns can be generated by the antenna for interference canceling. To reduce the size and cost, the antenna employs the configuration of electronically steerable parasitic array radiators (ESPARs). The parasitic elements are 12 folded monopole antennas, which surround a short monocone antenna. The short monocone antenna serves as the driven element. Each folded monopole is loaded with a p-i-n diode, and by controlling the dc voltages applied to the p-i-n diodes, the antenna can achieve electronic beam steering and adaptive beamforming. To prove the concept, a prototype antenna was developed whose frequency bands are 1.8-2.2 and 2.85-3.15 GHz. The height of the antenna has been reduced to 0.12 λ at 1.8 GHz.]]> 10 1349 1352 789 2 in size. Power conversion efficiency (PCE) represents a major challenge for WPT, especially at low input power levels. Our results indicate that PCE is related to the distributions and the combinations of input power spectrum. Therefore, a novel multitone powering system is developed to achieve a high output voltage. Experimental results indicate that the induced voltage can increase by 3.8 times over that of multitone WPT. Furthermore, wireless multitone powering can produce a 1.92-V output, i.e., an improvement of 14%, with a small average power of -5.3 dBm at 1.83 GHz.]]> 10 1353 1357 798 10 1358 1361 644 10 1362 1365 563 M-ary coding capability for large ID coding diversity.]]> 10 1366 1368 591 10 1369 1372 675 S₁₁| <; -10 dB) for either horizontal or vertical polarization and from 1.35 to 1.9 GHz for the 45° linear polarization. Measured results on frequency tuning ranges and radiation patterns agree well with numerical simulations.]]> 10 1373 1376 430 0×0.14λ₀. The measured gain and efficiency of the fabricated antenna have been improved to 2.3 dBi and 79%, respectively, at the zeroth-order resonant frequency of 2.3 GHz.]]> 10 1377 1380 879 10 1381 1384 368 10 1385 1388 457 2, and the antenna operates at 1.25 and 2.1 GHz. The relative bandwidths are 4.18% and 11.4%, respectively.]]> 10 1389 1392 733 10 1393 1396 425 S₁₁ ≤ -10 dB and covers the main range of the pulse spectrum. The front-to-back ratio of the amplitude of the received signal reaches about 3.5:1.]]> 10 1397 1400 531 10 1401 1404 627 10 1405 1408 895 10 1409 1412 1002 10 1413 1416 674 10 1417 1420 658 10 1421 1424 417 Q, and matching behavior of these antennas.]]> 10 1425 1428 424 10 1429 1432 741 10 1433 1436 586 10 1437 1440 554 10 1441 1444 761 10 1445 1448 692 10 1449 1452 744 3 covers the frequency bands DCS (1710-1880 MHz), PCS (1850-1990 MHz), WLAN (2.3-2.5 GHz), and LTE Band 7 (2.5-2.6 GHz), all with circularly polarized radiation patterns and gain at broadside angle varying between 5-9 dBic. A prototype antenna was fabricated and experimentally verified for the sum mode for both the impedance matching and radiation pattern characteristics. This antenna can also be used in monopulse radar tracking and transmit/receive communications after cavity backing.]]> 10 1453 1456 1004 10 1457 1460 676 0 × 0.67λ₀ × 0.83λ₀ at the working frequency. The resonant mode of the proposed cavity antenna is excited by a coaxial feeding probe, and circular polarization is realized by an inserted perturbation screw. The measured impedance bandwidth for | S₁₁| ≤ -10 dB and 3-dB axial-ratio bandwidth are 1.02 GHz (6.07-7.09 GHz) and 320 MHz (6.59-6.91 GHz), respectively. The measured gain is 8.5 dBic across the whole 3-dB axial-ratio bandwidth. The measured 3-dB axial-ratio beamwidths at the central frequency are 150^° and 148^° in the xoz- and the yoz-planes, respectively, which is wide enough to cover the >; 0-dBi gain beamwidths of 120^° for practical engineering applications. The measured and the simulated results show good agreement.]]> 10 1461 1464 754 10 1465 1468 678 S₁₁ <; -10 dB) of 120% (3-12 GHz). The proposed cavity-backed PMA prototype antenna was fabricated, and experimental verification was performed for impedance matching and radiation patterns. The measured results show reasonable agreement with the simulated ones.]]> 10 1469 1472 1050 C_n is calculated from data measured over a one-year period using its definition relation. Linear regression in heights is applied to a structure constant vertical dependence to obtain single and joint annual statistics of the near ground value of C_n and of its vertical gradient in the lowest troposphere. Approximate probability models are given with C_n being log-normal and the vertical gradient normally distributed.]]> 10 1473 1475 530 10 1476 1479 933 10 1480 1483 609 10 1484 1487 570 10 1488 1490 553 10 1491 1494 691 10 1495 1498 709 10 1499 1502 1007 10 1503 1506 804 10 1507 1511 812 10 1512 1515 577 10 1516 1519 609 ${-}{hbox{51}}^{circ}$ to 48$^{circ}$ via changing the parameters of CSRR structure.]]> 10 1520 1523 717 10 1524 1527 650 $LC$ resonant tanks, act as high-impedance elements at their resonance frequencies, and different effective $lambda/4$ sections can be achieved in the monopole by placing them at proper locations. Thus, the first working frequency is related to the length of the monopole, while the additional bands are controlled by the resonance frequencies of the OCSRRs. Moreover, the proposed antennas present monopolar radiation characteristics at all the operation bands. Two prototypes are designed, manufactured and measured: 1) a single-loaded OCSRR dual-band printed monopole antenna covering the Bluetooth and IEEE 802.11a/b/g/n bands (2.40–2.48 and 5.15–5.80 GHz, respectively); and 2) a triband prototype based on the same design, but with an additional OCSRR designed to also cover the IEEE 802.11y frequency band (3.65–3.70 GHz). Both antennas are printed on a single-layer of a low-cost substrate, resulting in very compact designs.]]> 10 1528 1531 665 $lambda$ ) and a folded cylinder diameter of 10 mm. A 74% size reduction is achieved after CSRR loading. The antenna located at the outermost surface not only functions as an electromagnetic radiator and an EMI shield, but also serve as a mechanical packaging structure.]]> 10 1532 1535 548 10 1536 1539 774 10 1540 1542 638 $lambda/24$ and extremely light weight, which renders it attractive for use in applications such as broadband arrays and portable wireless devices.]]> 10 1543 1546 684 10 1547 1550 956 10 1551 1554 855 10 1555 1558 876 10 1559 1562 1111 10 1563 1566 977 ${ z}$-dipole is employed as a straightforward example.]]> 10 1567 1570 677 10 1571 1574 716 10 1575 1578 481 10 1579 1581 520 $Omega$ source without any matching network and to yield high radiation efficiencies over their FBW $_{10, {rm dB}}$ bandwidths that are more than 75 times their original values.]]> 10 1582 1585 774 10 1586 1589 652 10 1590 1593 864 10 1594 1597 827 10 1598 1601 810 10 1602 1604 897 $mu$m, exploring the impact of material losses and impedance mismatch on the diffraction efficiency.]]> 10 1605 1608 519 10 1609 1609 26 10 1609 1609 26 10 1610 1614 108 10 1615 1666 889 10 1680 1680 189 10 C3 C3 5 10 C4 C4 5