In this paper, we describe the design of a hybrid 24 GHz RADAR array for termite detection and imaging. The array uses MIMO techniques to provide transmit beam steering and null steering in conjunction with the Matrix Enhanced Matrix Pencil (MEMP), which provides direction of arrival processing. We describe the selection of our MIMO orthogonal codes and test their suitability. Simulated results are shown for our array design and MIMO processing in a range of applications MIMO enables us to produce flexible nulling and beam steering for our transmitter array as well as reducing multipath re°ections and narrowband interference. MIMO processing also produces large time savings, enabling longer, more accurate acquisitions which can increase SNR. Transmitter beam-forming, produces an SNR improvement of 18.2 dB and can be used to reject clutter by up to 20 dB. Flexible nulling can reject interferers still further.

In this paper a novel approach to design multifrequency self-diplexed single patch antennas is proposed. This approach is based on a square microstrip patch antenna loaded with split ring resonators (SRRs). The working frequencies can be arbitrarily chosen and frequency ratios lower than 1.07 have been achieved. In addition self-diplexing characteristics are also achieved between transmitting and receiving ports by including SRRs in the feeding lines. Several prototypes have been manufactured and measured in the X-band showing good performance.

A fully-integrated bandpass filter using Q-enhanced and semi-passive inductors is design, implemented, and verified experimentally in a standard 0.18-μm CMOS process. The inductors achieve high-Q factors by using a tapped-inductor feedback technique to produce negative resistances. Compared with conventional transformer feedback, the proposed technique not only compensates resistive losses with low-power consumption but also provides a high-inductance inductor which is suitable for low-frequency applications. The 2-pole Chebyshev series-C coupled bandpass filter provides a frequency tuning range of 300 MHz around 2.65 GHz. Measurements shown that it consumes 2.4 mW to achieve 1.0-dB insertion loss, 12-dB return loss, 6.3-dB noise figure, and --- 2.5-dBm input P_1dB with a 950-MHz bandwidth at 2.8 GHz. And it consumes 5.6 mW to achieve 1.5-dB insertion loss, 10-dB return loss, 7.9-dB noise figure, and --- 4-dBm input P_1dB with a 700-MHz bandwidth at 2.5 GHz. The overall chip size of the filter is 0.7 mm×0.9 mm including all testing pads.

This paper presents a mini multi-band printed omni-directional antenna with v-shaped structure for radio frequency identification (RFID applications. The proposed multi-band antenna is developed from the initial v-shaped design which is only capable of working as a single-band antenna. By deploying a concept of dipole antenna to an initial design, the proposed antenna is accomplished to operate with two different modes of RFID system which are passive and active modes at frequencies of 915 MHz and 2.45 GHz respectively. The passive RFID tag is invented when a chip of UHF (Ultra High Frequency) is integrated with a proposed multi-band antenna. This passive tag, which is able to radiate with the measured signal strength, shows that the reading ranges are boosted almost two times compared to the conventional inlay antenna. The maximum reading range of passive RFID tag with inlay antenna is 5 m, though a reading range up to 10 m is achievable through the deployment of the proposed antenna at a measurement field. Implicitly, the measurements carried out on the antenna are in good agreement with the simulated values. Moreover, the size of the mobile passive RFID tag has been substantially as 100 mm x 70 mm, even though the antenna is fabricated with an inexpensive FR-4 substrate material. With the reasonable gain, coupled with cheaper material and smaller size, the proposed antenna has attractive potentials for use in RFID applications with multiple frequency antenna for active and passive tags.

A high-gain and broadband printed Yagi-Uda antenna is proposed. The microstripline-to-balance microstripline technique is adopted in the feeding mode of the active dipole, which can help to realize the balanced-unbalanced transformation. The ground of the microstrip feeding line can function as a reflector, and both the longer reflector and the shorter director can also help the antenna achieve wideband. By altering the area of the substrate, the antenna gain can be effectively improved. A printed Yagi-Uda antenna operating at 3.5 GHz has been designed and manufactured. Both the simulated and measured results indicate that there is a high positive correlation between antenna gain and the substrate area extended from the front of the director, and antenna broadband characteristic would not be changed at the same time. Moreover, the impedance bandwidth of the proposed antenna can achieve 27.4%, and the maximum gain in the operating band can reach 10.6 dBi.

Violations of the process of methylation reveal itself at the early stages of malignant transformation of cells, and the content of 5-methylcytosine can serve as a diagnostic test for tumor formation and treatment of disease. The carried out studies revealed the correlation of antitumor activity of MM-therapy (the coherent millimeter electromagnetic waves of low intensity) with inhibition of methylation of tumor DNA in vivo. It is established that an half-hour exposure of MM-radiation results in the tumor growth inhibition by 33,5% and a sharp suppression of the level of DNA-methylation -2.5 times. The results obtained in this experiment indicate the prospects of working out the MM-therapy for clinical oncology in the treatment of malignant neoplasms.

The nonlinear absorption of a strong electromagnetic wave caused by electrons confined in cylindrical quantum wires is theoretically studied by using the quantum kinetic equation for electrons. An analytic expression of the nonlinear absorption coefficient of a strong electromagnetic wave caused by electrons confined in a cylindrical quantum wire with a parabolic potential for electron-optical phonon scattering is obtained. The dependence of the nonlinear absorption coefficient on the intensity E₀ and the frequency Ω of the external strong electromagnetic wave, the temperature T of the system and the radius R of the wires is strong and nonlinear. Analytic expression is numerically calculated and discussed for a GaAs/GaAsAl quantum wire. The results are compared with those for normal bulk semiconductors and quantum wells to show the differences.

A novel G-shaped slot ultra-wideband (UWB) bandpass filter with a very narrow notched band is proposed. The basic ultra-wideband filter is short-circuited stub bandpass filter consisting of shunted λ/4 short-circuited stubs and λ/4 connecting lines. To avoid the interferences such as WLAN signals. The G-shaped slot embedded in the stub filter is used to obtain the notched band inside the UWB passband. Additional U-shaped defected ground structures are adopted to improve the out-band suppression. Measured results show that the proposed filter has an ultra-wide bandwidth from 3.1 GHz to 10.6 GHz, and the insertion loss is less than 1 dB. Specifically, the fabricated filter possesses a 10 dB notched fractional bandwidth (FBW) of 2.36% at the notched center frequency of 5.8 GHz. It also achieves a stop band with 20 dB attenuation.

Combining a two-year measurement and numerical approach, a semi-empirical model has been developed for prediction of rain attenuation at Ka-band in northern Taiwan. This was done using the drop size distribution (DSD) measurement and the extinction coefficient calculated by T-matrix, followed by regressing with rain attenuation measurements in all seasons. The attenuation due to rain can be estimated by calculating the extinction coefficient over all of the rain drops within the antenna beam volume. Comparing with the measured data demonstrates that the proposed model proves sufficiently accurate for Ka-band signal attenuation in site specific. For purpose of cross reference, we also compared the proposed model with Crane and ITU-R-P838 rain attenuation models. The RMS error and chi-square test shows that the proposed semi-empirical model has better performance to predicted rain attenuation than Crane and ITU-RP383 models, implied that both model predictions may not be quite reliable in some specific areas. Analysis suggests that seasonal effects are strong in signal attenuation due to rain types. It means that rain rate itself is not a quite reliable enough to be the single parameter in the rain attenuation model.

Passive source localization has wide applications in array signal processing. In the practical applications, the observations collected by an array may be ``arbitrary"-field signals, i.e., which are either mixed near-field and far-field signals or multiple near-field signals or multiple far-field signals. With a cross array, a two-stage separated steering vector-based algorithm is developed to localize ``arbitrary"-field narrowband sources in the spherical coordinates. The key points of this paper are: i) different physical steering vectors of near-field and far-field sources are transformed into the virtual ones with the same form, thus linearizing the quadratic phases of near-field sources and allowing the same operations for near-field and far-field sources; ii) the virtual steering vector is separated into two parts and restored by introducing a special phase angle, and thus it is used to estimate the azimuth-elevation arrival-angles of ``arbitrary"-field sources; and iii) special Hermitian matrices are constructed using the separated physical steering vector and their eigenvalue decomposition (EVD) are performed, thus the ranges of near-field sources are easily obtained from the eigenvector being corresponding to the smallest eigenvalue. The proposed algorithm can localize ``arbitrary"-field sources without pairing parameters and multidimensional search. Simulation results are provided to validate the performance of the proposed method.

The T-match feed is a useful impedance matching tool for dipole antennas, especially for electrically short dipoles with capacitive loads. The Uda model has been extensively tested for accuracy in the literature for the special case of the folded dipole, but not for the more general T-match dipole, which is often used for RFID antenna design. We investigate the accuracy of the Uda model for this more general case and show that aspects of the model become inaccurate for a number of practical scenarios. Nevertheless, we show that the model can still be used as a guide to T-match dipole designs.

This paper proposes a robust Computer-Aided Design (CAD) tool for an Ultra-Wideband (UWB) antenna system which successfully integrates the design of the transmitting antenna, the receiving antenna and the shaping of the transmitted pulse. The distinctive features of this tool include: the efficient characterization of transfer function in terms of an analytical model, the effective evaluation from system point of view and the simultaneous optimization of multiple objectives. Using this tool, an automatic and efficient design can be realized to deliver the UWB antenna system upon the optimal performance.

Modulation methods such as homodyne and heterodyne detections are employed in A-SNOM in order to eliminate serious background effects from scattering fields. Usually, the frequency-modulated detection signal in apertureless scanning near-field optical microscopy (A-SNOM) is generally analyzed using a simple dipole-interaction model based only on the near-field interaction. However, the simulated A-SNOM spectra obtained using such models are in poor agreement with the experimental results since the effects of background signals are ignored. Accordingly, this study proposes a new phenomenological model for analyzing the A-SNOM detection signal in which the effects of both the dipole-interaction and the background fields are taken into account. It is shown that the simulated A-SNOM spectra for 6H-SiC crystal and polymethylmethacrylate (PMMA) samples are in good agreement with the experimental results. The validated phenomenological model is used to identify the experimental A-SNOM parameter settings which minimize the effects of background signals and ensure that the detection signal approaches the pure near-field interaction signal. Finally, the phenomenological model is used to evaluate the effects of the residual stress and strain in a SiC substrate on the corresponding A-SNOM spectrum.

The modified Watson transform is applied to the Mie series for the electromagnetic wave transmitted into the double negative cylinder due to high frequency plane wave incidence The Debye series expansion is adapted to the transmission coefficients to reveal the transmission mechanism at high frequency. The first term of the Debye series is examined. Two kinds of geometrical shadow regions and two kinds of geometrically lit regions are shown to exist. The field formation mechanisms in these regions are indicated. Several differences between a double positive cylinder and a double negative cylinder are determined. The field computations are performed in the geometrical shadow and the geometrically lit regions for the first term of the Debye series. The residue series and steepest descent computations are shown to be in good agreement with the Mie series computations.

In this paper a semi-analytical representation of the coupling impedance between coils composed of filamentary turns located between two layered media is provided on the basis of the spectral expansion of the fields involved in the system. Both media are composed of several layers of homogeneous materials characterized by their physical properties occupying, respectively, a half-space bounded by a plane. The domain in the middle, where the coils are placed, has vacuum properties. The development is focused on misaligned circular coils placed in parallel planes with respect to the media boundaries. Two different behavioral descriptions have been considered: first, the system is made up entirely of magnetic insulators and the coupling impedance is therefore purely inductive; second, at least one medium is an electrical conductor and, as a consequence, an additional resistive component emerges when the coupling impedance is evaluated. In the latter case, the coupling impedance exhibits a frequency dependence due to the dispersive effects associated with the induced currents generated in the conductive media. The model developed is verified by means of a comparison between numerical and experimental results.

This paper presents a cavity backed slot antenna design with high gain and relatively small size. The large ground plane of the original design is cut 75%. Mushroom cells, ground plane orientation, and bending edges in the ground plane have been employed to improve the antenna gain. A 19.25 dB maximum gain is obtained with an average gain of 18.2 dB in the entire operating band.

Light scattering from small spherical particles has applications in a vast number of disciplines including astrophysics, meteorology optics and particle sizing. Mie theory provides an exact analytical characterization of plane wave scattering from spherical dielectric objects. There exist many variants of the Mie theory where fundamental assumptions of the theory has been relaxed to make generalizations. Notable such extensions are generalized Mie theory where plane waves are replaced by optical beams, scattering from lossy particles, scattering from layered particles or shells and scattering of partially coherent (non-classical) light. However, no work has yet been reported in the literature on modifications required to account for scattering when the particle or the source is in motion relative to each other. This is an important problem where many applications can be found in disciplines involving moving particle size characterization. In this paper we propose a novel approach, using special relativity, to address this problem by extending the standard Mie theory for scattering by a particle in motion with a constant speed, which may be very low, moderate or comparable to the speed of light. The proposed technique involves transforming the scattering problem to a reference frame co-moving with the particle, then applying the Mie theory in that frame and transforming the scattered field back to the reference frame of the observer.

Forward scattering effects have been studied and compared when nonhomogeneous medium is illuminated by coherent and quasi-noise sources operating in mm-wave and microwave ranges. Double-layers dielectric structure simulating Fabry-Perot resonator properties was employed to develop a relevant model used for comparing transmittances of both coherent and noise signals. Experiments with nonhomogeneous materials such as coal, wood chips, sand and others have proved the basic modeling predictions and the role of noise bandwidth in averaging process important for material characterizations. It was found out that efficient averaging associated with noise nature of probing signal can be reached for the relative noise bandwidth of 25% and more.

A 50 to 550 MHz wideband gallium nitride (GaN) HEMT power amplifier with over 43 dBm output power and 63% drain efficiency has been successfully developed. The demonstrated wideband power amplifier utilizes two GaN HEMTs and operates in a push-pull voltage mode Class D (VMCD). The design is based on a large signal simulation to optimize the power amplifier's output power and efficiency. To assure a wideband operation, a coaxial line impedance transformer has been used as part of the input matching network; meanwhile, a wideband a 1:1 ferrite loaded balun and low pass filters are utilized on the amplifier's output side instead of the conventional serial harmonic termination.

The purpose of this paper is to extend to spinor electromagnetism the differential forms, based on the Cartan exterior derivative and originally developed for tensor fields, in a very compact way. To this end, differential electromagnetic forms are first compared to conventional tensors. Then, using the local isomorphism between the O (3,C) and SL (2,C) groups supplying the well known connection between complex vectors and traceless second rank spinors, they are generalized to spinor electromagnetism and to Proca fields. These differential forms are finally expressed in terms of Hertz potentials.