A simple traffic surveillance system based on the extraction of features from range-Doppler radar images is addressed. The concept exploits the High-Resolution Radars (HRR) properties. Specifically, a procedure is proposed to obtain some features from the HRR non-cooperative targets to enable their classification. These features are the distance, radial velocity, radial longitudinal dimension of the target, its integrated range-Doppler image based on a group of range-Doppler frames from each target, and both the coherent and non-coherent integrated range profiles. Experimental results from real scenarios using a high-resolution Linear-Frequency-Modulated Continuous-Wave (LFMCW) millimetre-wave radar are shown.

Electric fields have been widely used for the treatment of neurological diseases, using techniques such as non-invasive brain stimulation. An electric current controls cell excitability by imposing voltage changes across the cell membrane. At the same time, the presence of the cell itself causes a re-distribution of the local electric field. Computation of the electric field distribution at a single cell microscopic level is essential in understanding the mechanism of electric stimulation. In addition, the impact of the cellular biophysical properties on the field distribution in the vicinity of the cell should also be addressed. In this paper, we have begun by first computing the field distribution around and within a spherical model cell. The electric fields in the three regions differed by several orders of magnitude. The field intensity in the extracellular space was of the same order as that of the externally applied field, while in the membrane, it was calculated to be several thousand times greater than the applied field. In contrast, the field intensity inside the cell was greatly attenuated to approximately 1/133th of the applied field. We then performed a detailed analysis on the dependency of the local field distribution on both the electrical properties (i.e., conductivity, dielectricity), and the geometrical properties (i.e., size, membrane thickness) of the target cell. Variations of these parameters caused significant changes to the amplitude and direction of the electric field around a single cell. The biophysical mechanisms of such observations and their experimental implications are discussed. These results highlight the significance of considering cellular properties during the electric stimulation of neuronal tissues.

Radar-based microwave imaging is being investigated as a complementary diagnostic tool for breast cancer detection. One of the major challenges associated with radar-based breast imaging is the removal of the overwhelming reflection caused by the skin. This paper presents an algorithm that has been designed for realistic 3D scenarios. The algorithm is tested on a variety of realistic 3D numerical breast models, as well as measured data from a phantom and patient. In all cases, the reflections from the skin are significantly reduced, facilitating detection of known tumors.

In this hybrid combined time domain (TD) and frequency domain (FD) approach, one can generate the early-time response using the method of marching-on-in-time (MOT) and use the method of moment (MOM) to generate the middle-frequency response, as the low frequency data may be unstable. The early-time and the middle-frequency data provide the missing low and high frequency response and the late-time response, respectively. Generation of a wide-band response using partial information of the TD data and FD data has been accomplished by the use of the continuous and discrete Laguerre functions.

This paper presents the estimation of emissivity of calibration load using discretized scattering simulation data in bistatic reflection measurement, and analyzes the effect of several measured parameters on emissivity of calibration load. In the analysis of the impact of measured parameters on emissivity, a new calibration target is designed to improve the accuracy of emissivity measurement. In this bistatic measurement, the scattering from calibration load is simulated by FDTD (Finite-Difference Time-Domain) method. Based on Kirchhoff's law, the emissivity of calibration load is estimated by the discretized scattering data composed of different scanning angle interval and sampling azimuth planes. By the studies of simulation results, the estimation accuracy of emissivity of calibration load can be improved by selected appropriate measured parameters in bistatic reflection measurement.

In this paper, the applications of shunt open stubs are reported based on asymmetric half-wavelength resonators structure. To demonstrate the design ideas, the analysis methods of ABCD matrix and equivalent circuit are used. The multi-band bandpass, miniaturization and harmonic suppression by application of the shunt open stubs are demonstrated. The measured insertion loss of the dual-band filter with the center frequency of 1.9 and 5.8 GHz is less than 2.7 dB. The insertion loss of the tri-band filter with the center frequency of 1.5, 4 and 6.3 GHz is less than 2.7 dB. Furthermore, a compact bandpass filter with size around 12.3 mm*11.5 mm is designed and fabricated. The bandwidth of the filter is 120 MHz with the center frequency of 2.4 GHz and the insertion loss is less than -3 dB. Especially, the insertion loss is less than -20 dB from 2.8 GHz to 7 GHz. For the filters above, the simulated results and the measured results agree well.

A novel Ku-band push-push dielectric resonator oscillator (DRO) using substrate integrated waveguide (SIW) power combiner is presented. Compared with the traditional push-push oscillator, the proposed push-push DRO can realize high fundamental harmonic suppression, due to the use of a SIW power combiner, whose cut-off frequency is designed within the range of the fundamental and second harmonic frequency. Moreover, the isolation of two fundamental frequency oscillators can be enhanced, while the power combiner operates at the second harmonic frequency to maximize the output power. As shown in the experimental results, the centre frequency of push-push DRO is 14 GHz, with a frequency tuning range of 30 MHz. The suppression of the fundamental frequency is 28.59 dBc while the third harmonic suppression is 22.54 dBc, respectively. Furthermore, the phase noise can achieve -98.01 dBc/Hz at 100 kHz offset from the centre frequency.

A loss of large aperture quasi-optics which consist of a lens and a feed antenna is firstly measured using a radiometer receiver via the modified reference control method for a W-band imaging radiometer system. The quasi-optical loss is mainly decided by the dielectric loss of the lens with good quasi-optical transformation efficiency between the lens and the feed antenna. The quasi-optics composed of an aspheric lens and a dielectric rod antenna are designed for high resolution, low aberration, and compact size. The fabricated quasi-optics with the aperture diameter of 500 mm have the quasi-optical transformation efficiency of more than 95%. The radiometer receiver is designed applying a total power type and a direct conversion topology for simplicity, compact size and low temperature sensitivity. The manufactured receiver has the temperature sensitivity less than 1 K for both a hot source and a cold source. The calculated and measured results of the quasi-optics are very well matched by approximately 1.6 dB. The expected measurement errors by the reference control method are also analyzed as the functions of the characteristic parameters of the radiometer receiver.

This paper studies the bit error rate (BER) performance of non-coherent impulse-radio ultra wideband (IR-UWB) correlation receivers in the IEEE 802.15.3a channel for combined binary pulse amplitude modulation-pulse position modulation (BPAM-PPM) scheme. The BER performance is based on the channel averaged signal-to-noise ratio (SNR). The study includes simple transmitted reference (TR), differential TR (DTR), and energy detection (ED) receiver structures. Moreover, different performance parameters are addressed, namely the signal bandwidth integration window factor, number of pulses per bit, and receiver power consumption. ED receivers with BPAM-PPM are shown to outperform simple TR receivers and have a performance which approaches that of differential TR (DTR) receivers with smaller power consumption for the same design parameters.

P4 polyphase code is well known in microwave pulse compression technique. There are different reduction techniques to reduce the sidelobes of P4 code. This paper presents a new sidelobe reduction technique which its results are excellent. To valid our work, other sidelobe reduction techniques such as Woo filter and modified forms of Woo filter are investigated and compared with the technique presented in this paper. Results show that the method introduced in this paper produces better peak side lobe ratio (PSL) and integrated side lobe ratio (ISL) than other solutions.

Time harmonic electric and magnetic fields inside a parallel plate DB boundary waveguide are derived and fractional curl operator is utilized to study the fractional parallel plate DB waveguides. The DB boundary conditions are incorporated by assuming the behavior of boundary as perfect electric conductor (PEC) for transverse electric mode and perfect magnetic conductor (PMC) for transverse magnetic mode. For this purpose a general wave propagating inside the parallel plate wave waveguide is assumed and decomposed into TE and TM modes. Behavior of the fields and transverse impedances of the walls of guide are studied with respect to the fractional parameter describing the order of the fractional curl operator. The results are compared with the corresponding results for fractional waveguides with PEC walls.

A compact reconfigurable antenna integrated with stepped impedance stub (SIS) loaded stepped impedance resonator (SIR) and SIS loaded hexagon stepped impedance resonator (HSIR) for ultra wideband (UWB) applications is proposed in this paper. The reconfigurable UWB antenna can work as a UWB antenna and a dual notch band UWB antenna by controlling the switches ON and OFF. The proposed two notch bands are obtained by embedding a SIS-HSIR on hexagon radiation patch and a SIS-SIR on coplanar waveguide (CPW) excitation line. The reconfigurable characteristic is achieved by means of two ideal switches. The proposed reconfigurable antenna has been designed, fabricated and measured. The experimental results show that the proposed reconfigurable antenna has a multi-mode function and good omni-directional characteristics.

A new permittivity is defined for anisotropic dielectrics with permanent polarization, which allows obtaining simple connections between the quantities of electric field. As an application, using the defined quantity, we will demonstrate advantageous forms of the refraction theorems of the two-dimensional electric field lines at the separation surface of two anisotropic dielectrics with permanent polarization, anisotropic by orthogonal directions.

This paper deals with the problem of detecting potential suicide bombers wearing concealed metallic and dielectric objects. The data produced by Millimeter-Wave-Radar system, working on a Multiple Frequency-Multiple Transmitters and Multiple Receivers configuration (MF-MTMR), is synthetically generated by an electromagnetic code based on Finite Differences Frequency Domain (FDFD) method. The numerical code provides the scattered field produced by the subject under test, which is later processed by using a multiple bistatic Synthetic Aperture Radar (SAR) algorithm. The blurring effect produced by the Point Spread Function (PSF) in the SAR image is removed by applying a regularized deconvolution algorithm that uses only magnitude information (no phase). Finally, the SAR algorithm and the deconvolution procedure are tested on a person wearing metallic and dielectric objects. The SAR response of dielectric rods is quite different from the metallic pipes. Our algorithm not only distinguishes between cases but also is capable of estimating the dielectric constant of the rods. Each constitutive parameter directly maps to the dielectric constant of explosive compounds, such as TNT or RDX, making feasible the detection of potential suicide bombers.

RF radiation due to corona and dry-band arc discharges have been observed using an antenna. Variations in radiated energy were observed due to change in the distance between two water droplets, the contact angle and the volume of the droplets, and the condition of the insulator surface. Changes in the frequency spectrum within the 800 MHz-900 MHz and 1.25 GHz-1.4 GHz frequency bands have been used to identify the transition from corona discharge to dry-band arc discharge. The 800 MHz-900 MHz emission band has also been used to monitor the condition of the insulator. These findings highlight the potential for RF sensing in the identification of partial discharges and insulator condition monitoring.

In this work, the enhancement in photonic band gap (PBG) in a dielectric-semiconductor photonic crystal (DS PC) is investigated. We consider two possible schemes that can be used to enhance the PBG in the near-infrared region. The first scheme is to add an ultrathin metal layer into the DS PC such that a structure of ternary metal-dielectric-semiconductor (MDS) PC is formed. The second scheme is to make use of the heterostructured PC. In scheme 1, it is found that the addition of metal layer will significantly move the left band edge to the shorter wavelength position, leading to an enlargement in the PBG. This enlargement can be extended as the thickness of metal film is increased. In addition, a pronounced enhancement in PBG is achieved when the metal with a higher plasma frequency is used. In scheme 2, we find that the PBG can be significantly enlarged compared to scheme 1. In addition, the increase in the band extension is shown to be four times larger than that in scheme 1. The results illustrate that, in order to enhance the PBG, the use of scheme 2 is superior to scheme 1. The enhancement of near-infrared (NIR) PBG is of technical use in the optical communications.

In this paper, a new method to analyze arbitrary shaped microstrip patch antennas is introduced. This method uses the multiport network model (MNM) together with a mathematical approximation called the "Pade approximation" such that the antenna input impedance obtained from the multiport analysis is approximated as a rational function of polynomials. Then, the roots of the denominator of this rational function are used to determine the antenna resonant characteristics. This new method is more time efficient than the standard multiport analysis because the evaluations are made at a single frequency. In the standard method, evaluations are made at multiple frequency values throughout the analysis. Results obtained by the new method are verified using the examples of rectangular and slot loaded compact microstrip patch antennas. Computational efforts for both procedures are presented.

This paper presents a conical monopole antenna with two C-shaped slots to provide a frequency stopband to suppress interference. Compared to previous work reported in the literature, the antenna provides increased gain suppression to vertically polarised signals within the notch-band of up to 41.5 dB in four specific directions. It also yields omni-directional radiation patterns at frequencies throughout the operating band, outside the rejection band. The four null directions in vertically polarised plane at the notched band frequency are explained by an analysis of simplified equivalent current sources. The effect of different length of slots has been investigated. Two methods to control the stop band directions are also discussed.

A novel 180° hybrid is proposed, based on a modified Gysel power combiner, using phase shifter and ground bridge for the difference output. Also the Defected Microstrip Structure has been used to increase the hybrid's phase matching. All steps of the design are simulated using HFSS 11 and the final design is validated by the fabrication. It has good results between 7 GHz to 10 GHz and can be used between 6 GHz to 11 GHz with less accuracy.

This work introduces and investigates various methods of improving spurious-free dynamic rage (SFDR) in HBT transimpedance distributed amplifiers by trading off transimpedance gain. The methods are theoretically analyzed in detail with design examples, compared against each other in terms of performance and the best tradeoff is determined. SFDR improvements of up to 9 dB are reported in our design examples.