IEEE Transactions on Antennas and Propagation

Design of effective wearable tags for UHF RFID applications involving persons is still an open challenge due to the strong interaction of the antenna with the human body which is responsible of impedance detuning and efficiency degradation. A new tag geometry combining folded conductors and tuning slots is here discussed through numerical analysis and extensive experimentation also including the i... View full abstract»

A compact, low cost and high radiation efficiency antenna structure, planar waveguide, substrate integrated waveguide (SIW), dielectric resonator antennas (DRA) is presented in this paper. Since SIW is a high Q- waveguide and DRA is a low loss radiator, then SIW-DRA forms an excellent antenna system with high radiation efficiency at millimeter-waveband, where the conductor loss dominates. The impa... View full abstract»

A novel integrated leaky-wave antenna-duplexer/diplexer, based on the CRLH uniform ferrite-loaded open radiating waveguide is introduced, demonstrated and characterized both numerically and experimentally. The duplexing operation, characterized by equal Tx and Rx frequencies, is performed directly within the antenna thanks to the non-reciprocity of the ferrite, thereby suppressing the need for a c... View full abstract»

A novel ultrawideband (UWB) antenna, called the Shark antenna, and designed especially for transient applications is proposed in this paper. A Shark antenna array is also conceived in order to obtain a high power UWB pulse radiation source through the frequency band [800 MHz-8 GHz]. For this application, the elementary antenna must be compact, non-dispersive, and the array must have a high transie... View full abstract»

The equivalent self impedance of a perturbed array of metal dipoles is derived and the resonant effects upon plane wave illumination are studied. It is revealed that as a result of the perturbation, the scattering within a frequency range is dominated by the excitation of the odd mode. This corresponds to significant deviation compared to the unperturbed case. It is demonstrated that within this f... View full abstract»

Unmanned aerial vehicles (UAV) are extensively being used in exploration, surveillance and military applications. Such vehicles often collect data via special sensors and send the data back to the central station via wireless links. Embedded in wing structure printed antennas will eliminate the drag due to friction, and allow for extended load capability due to their extra light weight. In this wo... View full abstract»

The problem of generating a flat-top main beam with an arbitrary footprint for array elements placed in an arbitrary planar aperture is considered in this paper. Some simplifying properties of the Bessel functions, encourages the general framework of the paper to encompass patterns produced by circular aperture and eventually generalize it to arbitrary aperture geometries. In this regard two synth... View full abstract»

Synthesis of unequally spaced linear antenna arrays is considered in this paper. A recently developed new differential evolution algorithm is applied to solve the problem. Both position-only and position-phase synthesis have been studied. Effect of angle resolution has also been investigated. Synthesis results show that our algorithm is able to obtain better synthesis result reliably and efficient... View full abstract»

A C-band four-frequency resonant stacked-patch array antenna is developed for synthetic thinned aperture radiometer measurements of hurricane force wind speeds. This antenna is being integrated into an aircraft instrument referred to as the Hurricane Imaging Radiometer (HIRAD). Details of the antenna design are presented along with antenna performance tests and laboratory measurements using a full... View full abstract»

An electronically reconfigurable transmitarray device at 12 GHz is presented in this work. This paper highlights the functioning of this kind of device and thoroughly examines the proposed reconfigurable transmitarray. The architecture is discussed along with the design and selection of all the constituting elements and the prototypes for all of them. In order to add reconfigurability to the trans... View full abstract»

Frequency-invariant (FI) beamforming for wideband antenna arrays inevitably involves array aperture loss at the higher-end frequencies of the bandwidth. In order to minimize aperture loss and to fully utilize the array aperture at different operation frequencies, an optimal wideband beamformer for uniform linear array (ULA) is designed based on Dolph-Chebyshev's theory of beamforming. Different fr... View full abstract»

The design, fabrication, and integration of a frequency selective surface (FSS) with integrated photodiodes to allow for photonic calibration of phased array antennas is presented. The design includes embedding electrically short dipole antennas in each unit cell of the FSS, with a zero-biased photodiode placed across the gap of the diode. Fibers from an optical distribution network are passed thr... View full abstract»

Through-lossy-slab radar imaging will be shown at stand-off ranges using a low-power, ultrawideband (UWB), frequency modulated continuous wave (FMCW) radar system. FMCW is desirable for through-slab applications because of the signal gain resulting from pulse compression of long transmit pulses (1.926-4.069 GHz chirp in 10 ms). The difficulty in utilizing FMCW radar for this application is that th... View full abstract»

Breast lesion characterization for discriminating between localized malignant and benign lesions is important as the current breast screening techniques do not have the required specificity to be clinically acceptable. A method using ultrawideband (UWB) microwave imaging system for such classification is proposed in this paper. The early time portion of the backscatter breast response is processed... View full abstract»

Novel configurations based on Fractal Hilbert curves are proposed for realizing artificial magnetic materials. It is shown that the proposed configuration gives significant rise to miniaturization of artificial unit cells which in turn results in higher homogeneity in the material, and reduction in the profile of the artificial substrate. Analytical formulas are proposed for design and optimizatio... View full abstract»

A complete antenna pattern characterization procedure for spherical near-field antenna measurements employing a high-order probe and a full probe correction is described. The procedure allows an (almost) arbitrary antenna to be used as a probe. Different measurement steps of the procedure and the associated data processing are described in detail, and comparison to the existing procedure employing... View full abstract»

The phaseless techniques have been discussed in the antenna measurements community and the theories behind these techniques are well explained in literature. The issue of the noise and the presence of measurement errors are not investigated in details to provide strong impetus to the importance of phaseless measurements. In this paper the near-fields of a number of different types of antennas with... View full abstract»

A technique is proposed for the generation of planewaves in the total-field scattered-field (TFSF) formulation of the FDTD method. The method is developed using the 1D properties of a planewave and optimized projection of the 3D finite difference operators to the 1D domain. The result is an efficient and accurate planewave source that can be propagated on six 1D grids concurrent with the main simu... View full abstract»

An efficient finite-difference time-domain (FDTD) algorithm with a simple periodic boundary condition (PBC) is developed to analyze general periodic structures with arbitrary skewed grids. The algorithm is easy to implement and efficient in both memory usage and computation time. The stability criterion of the algorithm is angle independent and therefore it is suitable for implementing incidence w... View full abstract»

The Holland and Simpson thin wire formalism is a versatile technique to deal with wires in the FDTD method. This paper develops an approach to correctly perform a junction between several wires at any Yee's cell location. The application context is the wires parallel to Cartesian axes with any translation in the Yee's Cell. The sensitivity of the thin wire current to Cartesian shift is also minimi... View full abstract»

An efficient hybrid analysis which hybridizes surface-wire integral equations (SWIE) with physical optics (PO) approximation is presented for wire antennas attached to an electrically large aircraft platform. In the analysis, the whole surface of the platform and antennas is divided into three regions, namely, the method of moments (MoM) region, the PO region and a region referred to as the joint ... View full abstract»

A method is presented for enhancing the efficiency of integral equation solutions for antennas. In this paper, a folded coaxial guide junction, proposed to be part of a below the feed inductive load, is analyzed. Scattering parameters for the folded coaxial guide junction are developed to replace the coupling of the field accounted for by a coupled integral equation at the aperture joining two coa... View full abstract»

A well-conditioned coupled set of surface (S) and volume (V) electric field integral equations (S-EFIE and V-EFIE) for analyzing wave interactions with densely discretized composite structures is presented. Whereas the V-EFIE operator is well-posed even when applied to densely discretized volumes, a classically formulated S-EFIE operator is ill-posed when applied to densely discretized surfaces. T... View full abstract»