118 research outputs found
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No full textArchitecture Abstract This paper proposes a hybrid scanning antenna architecture for applications in mmwave intelligent mobile sensing and communications. We experimentally demonstrate suitable Wband leaky-wave antenna prototypes in substrate integrated waveguide (SIW) technology. Three SIW antennas have been designed that within a 6.5% fractional bandwidth provide beam scanning over three adjacent angular sectors. Prototypes have been fabricated and their performance has been experimentally evaluated. The measured radiation patterns have shown three frequency scanning beams covering angles from 11 to 56 degrees with beamwidth of 10±3 degrees within the 88-94GHz frequency range. Keywords Millimeter-wave mobile sensing and communications· W-band antennas· Leaky wave antennas
Design Method for Circularly Polarized Frequency Selective Surfaces
No full textThis paper proposes a design method for the realisation of circularly polarised frequency selective surfaces (CP FSS). An equivalent circuit model for a capacitive asymmetric loop FSS is proposed. For this model a set of nonlinear design equation for CP operation is obtained. Based on space mapping of the model and full-wave simulation, a fast converging design method for CP FSS synthesis is demonstrated for the first time.
Detection of an artificial target with low radar cross-section in presence of backscatter
No full textThis paper presents an approach to improve the detection of an artificial target with low radar cross-section in presence of clutter. The target proposed in the paper modulates the phase response of the circularly polarized incident signal by means of rotation. The same physical phenomenon can be used to steer the modulated response in a non-specular direction. The bi-static measurements of the response of the target have demonstrated good agreement with theoretical prediction as well as with full-wave simulation
Equivalent Circuit Model of Twisted Split Ring Frequency Selective Surfaces
No full textThis paper proposes a wideband equivalent circuit model for a twisted split ring frequency selective surface (FSS). Such surfaces can be used for modelling and design of polarisation sensitive surfaces such as circularly polarized selective surfaces as well as structures with asymmetric transmission. The proposed model is based extraction of equivalent circuit parameters from a single split ring (SRR) FSS and magnetic coupling from periodic eigenmode analysis of the coupled SRR. The resulting equivalent circuit model demonstrates excellent agreement with full-wave simulations
Metamaterial-based LTCC Compressed Luneburg Lens Antenna at 60 GHz for Wireless Communications
No full textThe paper presents a metamaterial based LTCC compressed Luneburg lens antenna for wireless communications. The antenna is designed at 60 GHz to utilize the unlicensed mm-wave spectrum available for short-range high-data-rate communications. The gradient index compressed Luneburg lens antenna is designed using the quasi-conformal transformation optics method. The design of the antenna is fully compliant with the standard LTCC process with a high-permittivity host material. The diameter of the antenna is 19 mm and the thickness is less than 2 mm. The peak antenna gain at 60 GHz of 16 dBi is demonstrated. Beam scanning capacity is demonstrated with 1 dB scan loss within ±25 degree field of view.</p
Electromagnetic wave diffraction from an infinite array of complex-shaped microstrip reflectors
No full textA numerical-analytical method is developed for solving surface integral equations (IEs) describing electromagnetic wave diffraction from arrays of complex-shaped planar reflectors. Solutions to these equations are regularized via analytical transformation of the separated singular part of the matrix kernel. Basis functions satisfying the metal-edge condition are determined on the entire surface of the complex region. The amplitude and phase responses of arrays consisting of polygonal reflectors are numerically investigated
A novel frequency-selective surface generating two-band pseudo-elliptic frequency response
No full textA novel frequency-selective surface (FSS) is introduced in this paper. The structure proposed is a single-sided printed circuit board (PCB) that generates a pseudo-elliptic type response with two closely spaced passbands. Such a multi-band operating regime is realized owing to additional higher modes excited in the meander-like apertures and involved in electromagnetic interaction. Passbands at the response are independently tuned by adjusting the geometrical parameters of the aperture. Numerical and measured data for X-band FSS are presented for different angles of incidence. Due to the high selectivity, a small frequency ratio of 1.27 for central frequencies of passbands of 4.2% and 5.5% bandwidths is achieved for a normal incidence of linearly polarized wave.</p
Calculation of loss in conductors of a superconducting shielded slotted line and a coplanar waveguide
No full textFinite conductivity in superconductors is taken into account by approximate boundary conditions imposed directly when deriving pair summatory equations, which are solved using the Galerkin method and the basis describing the edge singularity
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