In the present study, a novel periodic planar leaky‐wave antenna (PLWA) was designed, simulated, and fabricated based on the substrate integrated waveguide (SIW) technology. The antenna can scan the main beam from around −60? to +20? continuously with complete suppression of open stopband (OSB) by the sweeping frequency from 9.2 to 14.1?GHz. The proposed structure was designed to have circular polarisation (CP) in the entire operating frequency range, where the broadside or centre frequency is 12.25?GHz. Antenna gain in the broadside frequency is around 13 dBi. The radiation efficiency of the structure is improved and equalised through broadside, which is around 80% in the frequency band of operation. Also, series and shunt analysis wa

The polarizability tensors of a particle are its characteristic parameters, which once obtained, can be applied as equivalent representations of the particle in any problems involving plane wave illuminations. In this paper, the generalized Kerker’s conditions for unidirectional scattering are derived, in the case of normal and oblique incidence, in terms of the polarizability tensors of any arbitrary nanostructures in homogeneous media and located on dielectric substrates. In order to present structures that corroborate the conditions derived from such polarizabilities, first, the effect of constituent material on the frequency response of the nanoparticle is investigated. Then, the dimensions of nanostructures that satisfy the first and

The analysis and synthesis of metasurfaces are important because of their emerging applications in a broad range of the operational wavelengths from microwaves to the visible light spectrum. Moreover, in many applications, like optical nanoantennas, absorbers, solar cells, and sensing, the presence of a substrate is apparent. Therefore, understanding the effects of substrates upon the metasurfaces is important, as the substrates typically affect the resonance behaviors of particles, as well as the interactions between them. In order to consider the impacts of substrates, this paper develops a method for the characterization and homogenization of substrated metasurfaces. This approach is based on independent studies of the electromagnetic be

In this paper, we study the existence of a surface wave on bianisotropic metasurfaces (BMS) by using electric and magnetic polarizabilities. These polarizabilities connect the local electric and magnetic fields on BMSs with electric and magnetic surface polarizations. We have chosen the method based on surface polarizations because applying boundary conditions using surface polarizations gives a better physical insight than the other methods including surface impedance-based methods. Variations of the electric and magnetic surface polarizations are equivalent to electric and magnetic surface currents, respectively; so, the Variations lead to discontinuities of the magnetic and electric fields on the BMS’s surface. In BMS structures, one o

In the present study, a characteristic mode analysis (CMA) is proposed for the first time to design a periodic leaky‐wave antenna (LWA). By applying CMA to the unit cell of a periodic travelling wave structure, the open stopband is suppressed and circular polarization (CP) radiation is achieved. Also, some parametric studies are added to clarify the design processes. Eventually, to optimize the design, the series and shunt analysis is applied to the unit cell of the periodic travelling wave structure. Based on the proposed analysis, a wideband CP long microstrip LWA (MLWA) is designed and simulated. The MLWA can sweep the main beam from around −30? to +10? continuously through broadside by sweeping the frequency from 7.5 to 12.25 GHz.

In this letter, design, simulation and fabrication of a high gain and wideband waveguide slot array antenna at X-band frequency is presented. In order to reach the required bandwidth, the whole antenna array is divided into several sub arrays. The antenna designing process includes an iterative procedure to determine the antenna structure, the number of radiating slots in each sub array, the offset and length of each radiating slot along with the length and orientation of each coupling slot. For this purpose, a MATLAB program based on the Elliott formulae is developed. The full-wave simulation of the whole antenna array is carried out and the bandwidth and radiating pattern characteristics such as gain and sidelobe levels are measured. The

In this paper, an X-band low-profile monopulse array antenna with high aperture efficiency is proposed for target tracking applications. The proposed structure consists of a 112-element patch array antenna, a monopulse comparator, and a full corporate feed network which is composed of waveguide and microstrip dividers. The monopulse comparator and waveguide part of the feed network are produced out of a single-layer substrate as the back-end section. Also, the printed array antenna and microstrip part of the feed network are integrated as the front-end. Finally, the back-end and the front-end sections are integrated through 32 SMP connectors. The proposed design decreases the lateral size of the feed network and results in achieving a high

In this letter, design, simulation, and fabrication of a high-gain and wideband waveguide slot array antenna at X-band frequency is presented. To reach the required bandwidth, the whole antenna array is divided into several subarrays. The antenna designing process includes an iterative procedure to determine the antenna structure, the number of radiating slots in each subarray, the offset and length of each radiating slot, along with the length and orientation of each coupling slot. For this purpose, a MATLAB program based on the Elliott formulas is developed. The full-wave simulation of the whole antenna array is carried out and the bandwidth and radiating pattern characteristics such as gain and sidelobe levels (SLLs) are measured. The me

Cognitive radars have the capability of adapting the transmitted waveform with the dynamic state of target and environment, to enhance the radar performance. In this paper, a cost function is proposed for designing the waveform parameters in cognitive radars, along managing the radar time resources. The proposed cost function has the capability of adapting to any radar measurement vector. The purpose of the proposed cost function is to design the waveform parameters adaptively, so that a compromise between the different radar measurement errors is made. This compromise between the different radar measurement errors depends on the prior and posterior target state estimations. Both simulated target data and real target data are used for evalu

Abstract The present study considers detection of the weak Swerling targets which exist in the clutter Doppler cell of the Weibull-distributed ground-based clutter by means of Independent Component Analysis (ICA). We present a new detector based on convolutive ICA that is independent of target and clutter statistical distribution and has no need to the previous knowledge of the radar signals. For the detection of radar target using ICA, there are some problems that are solved by two wisely proposed approach through the detector. Synthetic generated clutter and target are used to show quantitatively and qualitatively the capability of the proposed ICA-based detector. Also, the method is tested against real-life data. Finally, the computatio

In this paper, a new type of hot wire acoustic vector sensor based on Polyacrylonitrile base carbon fiber, as a sensing element is presented. The vector sensor employs two suspended carbon fiber with micro size diameter and millimeter length as a pair of hot wires that are close together with hundreds of micron separation. Resistance-Temperature curve shows that the temperature coefficient of resistance is negative for carbon fibers. Sensor response to air flow, directivity index, frequency response and sensitivity of the sensor in two different bias voltage have been measured.