In many ways light and nanoscience do not mix well. By convention light can be focussed to a spot no smaller than about a micron whereas nano structures by definition are three orders of magnitude smaller in scale. However recent theoretical advances show how to control light at the nanoscale, provided we can find the correct materials for our devices. I shall describe these new theories, and how they enable us to concentrate light to better than a nanometre. In this way light can detect single molecules, and the huge concentrations of optical energy can force photons to interact with one another which they normally do not do.

The finite-difference frequency-domain (FDFD) method is a very simple and powerful approach for rigorous analysis of electromagnetic structures. It may be the simplest of all methods to implement and is excellent for field visualization and for developing new ways to model devices. This paper describes a simple method for incorporating anisotropic materials with arbitrary tensors for both permittivity and permeability into the FDFD method. The algorithm is benchmarked by comparing transmission and reflection results for an anisotropic guided-mode resonant filter simulated in HFSS and FDFD. The anisotropic FDFD method is then applied to a lens and cloak designed by transformation optics.

For the measurement of microwave device in high-power, traditional methods are inefficient, inaccurate and not on-line real-time measurement. A new type of high-power microwave impedance tuner (26.5 GHz~40 GHz) based on load-pull technique and a corresponding rapid calibration method based on curve fitting are proposed. A new structure using increased width rectangular waveguide slotted in the center is adopted as the main transmission line. In order to prevent the leak of electromagnetic waves transferring in rectangular waveguide, two choke grooves are added in upper cover plate of the waveguide cavity. The results (standing wave ratio range of 1.02~10.98, insertion loss of 0.063 dB at minimum standing wave ratio) show by practical measurement that this structure and method are feasible. The device can meet the requirement of design, and the new method has less time for calibration.

This paper provides a modified formula for calculating dielectric loss of dielectric resonator of working in TE_01δ mode in closed cavity. The measurement system is divided into six regions with all electromagnetic field distributions given in each region. Based on analyzing the formula of loss tangent published in literatures, a quality factor of a substrate is created, and a modified formula is proposed. Validating the modified formula, with three substrates as supports, the frequencies and unloaded quality factors of dielectric resonators made of two sorts of dielectric materials with permittivity 38 and 75 respectively are measured using a closed cavity method. The measured results are compared with those obtained by other well-known formulas and show a good agreement with the result given by the parallel plate method.

Inverse synthetic aperture radar (ISAR) imaging is an effective method to identify unknown targets regardless of weather and illumination conditions. Research results published regarding this topic have focused mainly on imaging and automatic target recognition (ATR) of single targets. However, targets generally fly in formation, so the applicability of ISAR images to ATR of multiple targets must be studied. This paper proposes an ATR procedure for targets flying in formation. ATR accuracy derived using five targets composed of point scatterers and the measured radar signal of a Boeing747 aircraft was as high as that of the solo flight in terms of SNR and the size of the training database; this result shows that ISAR is an adequate tool for ATR even if an image is contaminated by radar reflections from neighboring targets.

This paper presents a novel power divider with filtering responses. By using quarter-wavelength resonators with a novel feeding structure, both power division and bandpass responses are obtained, and compact size is realized. Discriminating coupling is utilized to suppress the third harmonic to obtain wide stopband. The isolation resistor is connected at two ends of the input feed line, and good isolation is obtained. Two transmission zeros are generated at two edges of the passband, resulting in high selectivity. For demonstration, a filtering power divider is implemented. Comparisons of the measured and simulated results are presented to verify the theoretical predications.

The transmission and reflection coefficients of electromagnetic waves propagating through the finite periodically layered chiral structure are defined both theoretically (using the propagation matrix method) and experimentally. The coefficients of the propagation matrix of the periodically layered chiral medium are obtained. The boundaries of the forbidden bands for a periodic medium, whose unit cell consists of two different chiral layers were determined. It is shown that the boundaries of the forbidden bands do not depend on the chirality parameter of the layers. It is found that for certain values of the layers thicknesses, the forbidden band widths tend to zero and that the proposed method for calculation of the reflection and transmission coefficients can be used to determine the effective constitutive parameters of artificial chiral metamaterials. The transmission and reflection coefficients of plane electromagnetic waves propagated through the finite periodically layered chiral structure were determined experimentally for 20-40 GHz range. A good agreement between the experimental results and theoretical studies of the forbidden band spectrum for the structure under research has been shown.

A multimode collocated microstrip patch antenna with reduced mutual coupling is proposed in this paper. The antenna is designed to achieve polarization and pattern diversity for use in multiple-input-multiple-output (MIMO) terminals. The four-port antenna resonates at 2.45 GHz and have total dimension of 1.03λ with reduced mutual coupling (< -20 dB) between its ports. It consists of a simple square patch and a square ring antenna, with a novel square ring slot defected ground structure (DGS). Square ring slot on ground improves isolation by 7 dB by reducing surface waves in both E and H planes. With defected ground structure (DGS), coupling between patch and ring antennas is about -25 dB and correlation factor is less than 0.1. Pattern diversity, mutual coupling and correlation coefficient between signals for a four-port antenna fabricated using FR4 substrate is discussed in this paper.

As the boundary of the universe which is explored by human expanded, antenna used in deep space exploration (DSE) could become too large to carry and deploy, miniature deep space probe based antenna arrays (MDSPBAA) provide a novel solution for the problem. This kind of antenna array may lower the difficulty of sending antenna to the area where is tend to be detected and may also monitor cost effectively in the work of deep space detect. However, turbulence and positional errors provide a challenging operational environment when it comes to the implementation of these systems. Turbulence will deteriorate SLL badly. In some cases, the level could be changed by almost 10 dB. Therefore, a SLL control algorithm is presented, which could well compensate the SLL which is caused by positional error.

The Casimir force between an ellipsoid and a plate can be tuned by using the combination of anisotropic materials and nonlinear materials exhibiting the AC Kerr effect. The force was obtained numerically by using the FDTD method, based on the Maxwell's stress tensor. The results indicate that the force can be significantly varied by changing the intensity and location of the laser, as well as the properties of material. The sensitive changing between ellipsoid and plate structure with different materials' properties provides new possibilities of integrating optical devices into nano-electro-mechanical systems (NEMS).

A planar compact multiband monopole antenna is presented for ultra-slim mobile handsets applications. The proposed antenna operates over 0.885 GHz-0.962 GHz and 1.69 GHz-3.8 GHz frequency bands with -6 dB impedance bandwidth that covers GSM900, GSM1800, GSM1900, UMTS, IMT2100, WLAN, WiMAX along with most of the higher LTE bands of modern mobile phone applications. The radiation characteristics of the antenna is analyzed in term of radiation patterns, peak realized gain, total radiation efficiency, and surface current distribution. The radiation patterns of the proposed antenna is dipole like which is suitable for mobile applications with 73-93% total radiation efficiency. The proposed antenna is investigated in free space as well as in actual mobile environment consisting of mobile plastic housing along with large metallic display screen and battery. No significant effect on the operating bands of the mobile antenna due to the actual mobile environment on the impedance bandwidth is observed. Specific absorption rate (SAR) computation is carried out on human head phantom. The computed values of SAR lie well below the specified limit over 1 g and 10 g of tissues. The parametric analysis is also carried out to understand the effect of the shape parameters.

In this paper, a novel folded metal-plate monopole antenna is presented for indoor digital television (DTV) signal coverage in the 454-1300 MHz band. The proposed antenna consists of a folded metal-plate with two asymmetrical bevels and a shorted pin connecting the metal-plate with a ground plane. The folded structure extends the lower frequency band and reduces the height of the antenna for better application to DTV. Experiment results show that the antenna achieves a bandwidth for |S₁₁| < -10 dB ranging from 454 MHz to 1300 MHz and shows stable radiation patterns in three coordinate planes.

This paper presents a novel method to design filtering power divider with compact size. Based on lumped elements, a novel topology is proposed and theoretically analyzed. The equivalent power splitting circuits and filtering circuits are characterized by even-odd-mode analysis. Closed-form design equations are obtained, and all the unknown parameters can be derived. Meanwhile, two transmission zeros are produced near the passband edges, resulting in high-selectivity quasi-elliptic responses. For demonstration, a filtering power divider is implemented. The circuit operating at 600 MHz occupies only 15 mm × 14 mm.

In this paper, an efficient three-dimensional Laguerre-based finite-difference time-domain (FDTD) method is used to analyze planar circuits. An iterative procedure is introduced to improve the accuracy. Both the time-domain waveforms and the S-parameters are presented. The numerical results show that at the comparable accuracy, the efficiency of the Laguerre-based FDTD method with an iterative procedure is superior to the FDTD method and alternating-direction implicit (ADI) FDTD method.

A novel compact and multiband dipole antenna with a planar fractal-inspired configuration is presented. Several series capacitances and a parasitic element are employed as loading. Results show that the loading improves the impedance matching and enables the proposed antenna to radiate at multiple frequency bands. In addition, the proposed loaded dipole antenna offers a high degree of miniaturization in comparing with the unloaded host dipole antenna. The simulated |S₁₁| response of the proposed loaded dipole antenna shows five distinct resonant bands with the center resonant frequencies of 1.52 GHz, 3.62 GHz, 4.6 GHz, 6.9 GHz, and 9.43 GHz. A fabricated prototype has compact dimensions of the 37 mm × 14 mm × 1.6 mm, and exhibits good agreement between the measured and simulated S-parameters.

A low-profile broadband dual-polarized antenna with high isolation and low cross polarization is presented in this letter. The proposed antenna employs two different feeding mechanisms. On one hand, two out-of-phase probes loaded with two small circular patches make the proposed antenna operate in horizontal mode. On the other hand, two pins connecting two eyebrow-shaped patches and the ground form a magnetic loop which enables the proposed antenna to achieve vertical polarization. By elaborately adjusting the feeding structures, measurements demonstrate that the proposed antenna not only achieves 10-dB return loss bandwidths of 49% (1.7-2.8 GHz) and 28% (2-2.65 GHz) for Port 1 and Port 2, respectively, but also maintains a high isolation better than 32 dB over the entire common frequency band. Meanwhile, within the main lobes, the cross polarization levels, both in E-plane and in H-plane, stay lower than -25 dB for Port 1 and -20 dB for Port 2. In addition, the proposed antenna with a profile of 0.13 achieves the maximum gains of 8.4 dBi for horizontal polarization and 8.2 dBi for vertical polarization.

For coherent jammers to wideband linear frequency modulation (LFM) radar, the ratio between jamming energy and signal energy is always constant. To enhance the jamming to signal ratio (JSR), a two-dimensional (2D) discretized coherent noise jamming (2D-DCNJ) method is first proposed in this paper, where the covering area of the noise jamming results in 2D imaging is limited to a certain shape and further discretized to centralize the jamming energy. Moreover, the idea of weighting is applied to 2D-DCNJ to control the distribution of jamming energy, which can present some particular deceptive characteristics. The relationship between jamming results and modulated noise is analyzed, based on which the procedure of generating the jamming signal is detailed, and the JSR performance is compared with the previous ones. Finally, the validity of the proposed method is demonstrated via numerical simulation.

In this article, a compact dual-band bandpass filter (BPF) using coupled open-loop resonators and an embedded center-grounded stepped-impedance resonator (CGSIR) is proposed. This filter operates at 2.1/5.2 GHz for WCDMA/WLAN applications. The first passband is generated by the proposed CGSIR, and the second one is created by the coupled open-loop resonators. Each passband can be controlled independently by adjusting the dimension parameters of corresponding resonators. Five transmission zeros (TZs) are generated due to the 0° feed structure and signal cancellation effects between electric couplings and magnetic couplings, which improve the filter band-to-band isolation level and skirt selectivity significantly. Moreover, the overall circuit size is very compact due to the embedded configuration. The measured filter performances are in good agreement with the simulated ones.

Based on the conventional finite-difference time-domain (FDTD) method, a novel dual-meshed technique is presented to deal with the underwater detection problems applying in low frequency electromagnetic wave. A transformation surface connecting the coarse cell with the fine cell is implemented by applying a total-field scattered-field source (TSS) technique, which is carried out by two-step FDTD simulation. The ratio of a coarse cell size to a fine cell size can be set as an arbitrary integer, such as N=10. Moreover, it is illustrates that non-physical reflection fields from the TSS surface are avoided by introducing the TSS surface. We have derived, in detail, the update equations of fields on grids of the TSS surface. Three cases of dealing with different underwater electromagnetic problems are discussed. Numerical results show that by analyzing the magnitude and phase of scattered fields from obstacles underwater we can distinguish the category of the obstacles which belongs to either a high resistivity body or a low resistivity body. Therefore, the proposed method provides us an effective tool for analyzing the electromagnetic response of materials underwater.

A novel Quasi-Yagi antenna with low radar cross section (RCS) is proposed in this paper. By using arrow-shaped Koch dipoles as the driver and director and cutting the ground of the antenna, the RCS can be reduced in the operating band of 5 GHz-8 GHz when the incident wave is perpendicular to the antenna plane. Wideband radar absorbing material (WRAM) with frequency selective surface (FSS) is devised to replace the metallic reflect plate of the antenna to reduce the RCS in the maximum radiation direction. The average RCS reduction of the antenna in the frequency band of 3 GHz-12 GHz is 8.0 dB. The simulated and measured results show that there is a considerable RCS reduction of the Quasi-Yagi antenna with WRAM, and the radiation performance is preserved at the same time.