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A simple method for the synthesis of rectangular and circular antenna arrays with independently specified beamwidth and sidelobe level is presented. It makes use of the Taylor one-parameter design method, and thus the resulting arrays have decaying sidelobes. Knowing that the array factor of the rectangular array is the product of the array factors of two linear arrays, the rectangular array is obtained...
This paper explains why antennas can achieve limited frequency tunability by mounting varactor diodes across slots. The reason is that majority of varactors have a resistance in parallel to the variable capacitor. Resistance mainly acts as a short and thereby the varactor loses its capacitive behavior at low frequencies ∼ 2 GHz. At higher frequencies, the varactor retains its capacitive effect. Simulations...
Massive multiple-input multiple-output (MIMO) systems is an emerging technology that is paving its way into wireless communication systems. Massive MIMO consists of tens or hundreds of antennas, which will result in an increase in capacity, reliability and performance. However, massive MIMO is facing many obstacles in terms of complexity due to the large number of antennas. In this paper, sparse code...
This paper presents an inventive and simple procedure for the design of a 2D slotted waveguide antenna (SWA) having a desired sidelobe level (SLL) and a pencil shape pattern. The 2D array is formed by a defined number of 1D broadwall SWAs, which are fed using an extra broadwall SWA. For specified number of identical longitudinal slots in both dimensions, the desired SLL and the required operating...
A simple method for the design of rectangular slotted waveguide antennas (SWAs) with specified sidelobe levels is briefly described, and is used to design an example SWA with 7 broadwall elliptical slots and sidelobes lower than −20 dB. A special corrugation geometry is then added to the SWA, where the uniform height of the corrugations controls the SWA's operation frequency. This height can be changed...
Multiple-input multiple-output (MIMO) with a spatial-multiplexing (SM) scheme is a topic of high interest for the next generation of wireless communications systems. At the receiver, neighborhood studies (NS) and lattice reduction (LR)-aided techniques are common solutions in the literature to approach the optimal and computationally complex maximum likelihood (ML) detection. However, the NS and LR...
The smart behavior of cognitive receivers is based on an efficient spectrum sensing, leading to an opportunistic use of vacant resources. Therefore, an error-free detection of spectrum white spaces is required to enable all the adaptive functionalities of cognitive radios. Practically, the RF tunable frontend is a source of various RF impairments that harm the accuracy of sensing techniques. On the...
In this paper, a circularly polarized antenna operating at 1.575GHz, for GPS applications is designed. The antenna has a square patch, with cross slots to ensure Right Hand Circular Polarization (RHCP) over the operating frequency range. Electronic Band Gap (EBG) structures are incorporated between the patch and the ground plane to reduce the back lobes. The antenna has a gain of 5.37dB. The design...
In a cognitive radio system, spectrum sensing is considered as the key step of the cognition cycle and the primary function of the opportunistic usage of the spectrum. In real world scenarios, spectrum sensing algorithms are sensitive to several factors especially the model uncertainty problem in low signal-to-noise ratio environments. In this paper, a blind detector based on the cyclostationarity...
Spectrum sensing is the key element in the implementation of a cognitive radio equipment allowing the utilization of vacant bandwidth unused by the primary users such as broadcasting white spaces. To implement suitable spectrum sensing techniques, RF front end is mandatory at the secondary devices. However, these front-ends are usually low cost devices implying then some RF impairments which may affect...
Spectrum sensing has been identified as the key step of the cognition cycle and the most important function for the establishment of cognitive radio. In this paper, a blind cyclostationary feature detector, which is based on the symmetry property of cyclic autocorrelation function (SP-CAF), is implemented and tested using universal software radio peripheral platform and GNU Radio open-source software...
In this paper, a metamaterial unit cell with low effective permeability attained over a specific frequency band is used to form a planar single-layer metamaterial structure, which is utilized as a lens for broadside gain enhancement of a patch antenna. The proposed metamaterial lens consists of an 8-by-8 matrix of Split-Ring Resonators (SRRs), and is positioned above a probe-fed rectangular patch...
In this paper, a simple method to estimate the relative permittivity εr and the tangential loss tan(δ) of wearable textiles is presented. Quarter-wavelength stub-line band-stop filters, based on jeans and cordura textiles, are designed assuming reasonable initial values of εr and tan(δ), fabricated and experimentally tested. The filter designs are then re-simulated, by tweaking the values ofεr and...
In this paper, a compact quad-band antenna based on Open Loop Resonators (OLRs) is presented. The antenna is microstrip line-fed, and is printed on a 40 mm × 35 mm × 1.6 mm FR4-Epoxy substrate over a partial ground plane. The incorporation of each OLR contributes a resonance that depends on the OLR's design frequency and electrical length. Ansoft HFSS, an FEM-based solver, is used to design and simulate...
A simple frequency-tunable antenna for cognitive radio is proposed. It features a narrow bandpass filter, rendered tunable with a single varactor, and embedded in the feed line of an ultrawideband antenna. A modified version capable of both ultrawideband and tunable narrowband operations is also presented. Due to the topology of the antenna, the required DC biasing lines are easy to design and leave...
Introduction to Electrical and Computer Engineering, EECE 200, is a required course for all first year students majoring either in Computer and Communications Engineering (CCE) or in Electrical and Computer Engineering (ECE) at the Electrical and Computer Engineering Department of the American University of Beirut (AUB). The objectives of this course are to introduce CCE and ECE students to the various...
In this paper a novel printed diversity antenna for WiMAX applications is proposed. The antenna consists of two identical monopoles, and operates over a wide band spanning the 2.8–4.7 GHz frequency range, over which it has high isolation of over 20 dB. The diversity performance of the antenna, which is attributed to the configuration of the slots placed in its ground plane, is assessed by calculating...
This paper presents a planar antenna for employment in overlay and underlay ultra-wideband cognitive radio (UWB-CR). The antenna can be operated as ultra-wideband, for underlay CR and for sensing in the overlay CR. When used in the overlay CR mode, the proposed antenna can selectively have one, two or three notches in the WLAN, WiMAX, and U-NII bands, to prevent interference to primary users operating...
In this paper, a polarization reconfigurable microstrip antenna, for WLAN applications, is proposed. The antenna structure is based on a reconfigurable feed network, which drives a circular patch. The approach, presented herein, is based on electronically reconfiguring the phase difference, between the antenna's feeding ports, to achieve polarization diversity. The proposed antenna is designed and...
In this paper, a modified Finite Volume Control (FVC) method is introduced and used to solve for the fields in a 3D rectangular waveguide. The FVC method finds its main applications in Computational Fluid Dynamics (CFD) problems and has been rarely used in Computational Electromagnetics (CEM). The 3D rectangular waveguide under consideration is coupled through its apertures to two infinite conducting...
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