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A second harmonic mixer appropriate for direct conversion recievers is realized in 0.18 μm SiGe technology. The realized topology offers a unique mechanism to prevent LO to RF leakage, thus, suppress the DC Offset voltage due to LO self mixing. The constant current consumption of the topology provides a proper isolation of the noise mixing operation from the supply lines. Large signal analysis of...
A novel compact slow wave structure (SWS) based on spoof plasmonic waveguide with meander lines in the terahertz (THz) and microwave frequency range is proposed. The use of the meander lines increases the effective length of the proposed structure thereby providing more path length for efficient trapping of the spoof surface plasmon polaritrons (SPPs). The meander line based SPPs structure is designed...
In this paper, the design and characterization of a GaN HEMT based class-AB power amplifier (PA) operating in LTE communication band (1.9–2.5 GHz) are presented. A model-based design procedure is adopted. Source and load impedances for optimum linearity, power and efficiency are extracted through source- and load-pull simulation. The implemented PA shows excellent performance on the whole frequency...
Microwave-based security camera systems have been implemented using different types of instruments to attain a real time, high resolution image representing dangerous concealed carry-on objects on people. Some designs achieved this goal but at a very high manufacturing cost that made them impractical as well as unfeasible. Moreover, such designs were made of a single receiver that led to loss of some...
This work demonstrates the design of an adaptive reconfigurable rectifier to address the issue of early breakdown voltage in a conventional rectifier and extends the rectifier's operation for wide dynamic input power range. A depletion-mode field-effect transistor has been introduced to operate as a switch and compensate at low and high input power levels for rectifier. This design accomplishes 40%...
We present a simple design of Quarter-Wave Plate (QWP) and Half-Wave Plate (HWP) of an all-dielectric metasurfaces based on Elliptic Dielectric Resonators (EDRs) of minor radius 2.5 mm, ellipticity τ (τ1=1.4 or τ2=1.6), relative permittivity 10.2, loss tangent 0.003 and thickness 5.12 mm. The metasurfaces transmissions under x- and y-polarizations of the incident electric fields were studied over...
A compact multiple-input-multiple-output (MIMO)/ diversity ultra-wideband (UWB) antenna with planar structure is presented in this paper. It comprises of two modified rectangular slot antennas excited by microstrip transmission lines. An inverted U-shaped slot is inserted in the feeding transmission line to create a band-rejection at WLAN band (5.15–5.825 GHz). The mutual coupling between the two...
Fading models of practical mobile radio channel may change over time and/or due to mobility being Rice, Rayleigh, double-Rayleigh, etc, depending on the nature of radio wave propagation, which results in a non-stationary channel. This work is based on investigation of fading figure (FF) that addresses non-stationarity nature of radio channels. The FF is represented by the parameter m of Nakagami-m...
This paper discusses the use of a one arm Archimedean Sinusoidal Spiral Antenna (ASSA) to capture high frequency signals generated by Partial Discharge (PD) in an oil filled transformer. The antenna is designed such that it blocks low frequencies which corresponds to corona and noise in the transformer and allows higher frequencies which result from harmful PD activities. The captured PD signals will...
In this paper a practical approach for calibrating coax-to-microstrip transitions for narrowband applications, is presented. The method is an in-fixture measurement technique, which uses afterward de-embedding procedure to achieve the target S-parameters result. It is performed by extracting the equivalent circuit models of both measurement fixture-halves. Compared to the other in-fixture measurement...
A miniaturized ultrawideband (UWB) multiple-input multiple-output (MIMO) antenna with reconfigurable band-notched characteristics is examined in this paper. The MIMO antennas exhibit a good impedance match over frequency band of 2.5 GHz–10.4 GHz, while exhibiting high isolation. The proposed MIMO antenna system consists of two complementary radiating patches and a common ground plane. Enhanced isolation...
In this paper, the performance of orthogonal frequency division multiplexing technique, over a measured underground mine channel at 2.4 GHz, is investigated. The effect of increasing the number of subcarriers as well as the guard interval length is considered. In a further step, the performance of the OFDM scheme when combined with multiple input multiple output system, using, the well-known, diversity...
In this modern era, mobile phone has great impact on daily life and is used for exchange of information in the form of text, audio, email and images. Though it has many positive impacts but its negative impact in teenagers can not be neglected. These negative impact can be reduced by continuous monitoring. This paper presents a novel user defined system model to detect abnormal behavior of cell phone...
Notch characteristic is implemented in a wideband four-arm sinuous antenna with a nominal gain of 4.5 dBi over an operational bandwidth of 2–7 GHz. The notch band is introduced at 4.9 GHz with a fractional bandwidth of % 2 at 4.9 GHz, the center frequency of notched band. The sinuous antenna is backed with a metallic cavity having a low profile of 30 mm. The antenna is working with two orthogonal...
This paper presents a novel microstrip antenna that consists of conducting circular patch with elliptical etched rings and partial conducting ground plane. The fabrication was done using Rogers 5880 LZ substrate, and the dimensions are selected to be 45mm × 31mm × 1.27 mm. Split Ring Resonators (SRRs) will be used to enhance gain performance for wide frequency band. The Split Ring Resonator design...
Design of a wideband cascaded unit element microstrip bandpass filter (UEBPF) operating along the whole X-band (8–12 GHz) is presented with satisfactory agreement between theoretical and measurement results. Simplified real frequency technique (SRFTs) has been utilized in Richards domain to design the UEBPF, whose driving point impedance function is then synthesized by a "high precision Richards...
In this paper, a sparse direction-of-arrival (DOA) estimation based on a shifted coprime array configuration is proposed. The proposed array utilizes two uniform linear arrays (ULAs), one of them is shifted from the other by certain displacement. The displacement is optimized such that the number of lags in the difference coarray is increased. Thus, the value of this displacement changes for different...
In this paper, new polynomial and neural network models for power amplifier digital pre-distortion are introduced. The motivation behind the suggested models is having low complexity models that maintain good error performances. Also, this paper discusses the comparison between polynomial and neural network models in terms of model complexity and error performance before and after applying a compressed...
This paper presents a new technique, that does not require the use of spatial smoothing, for detecting the directions of coherent signals impinging on a Uniform Circular Array (UCA). The new technique is based on transforming the original UCA into an equivalent Virtual Uniform Linear Array (VULA) upon which a Toeplitz re-construction is employed to alleviate the inaccuracies incurred in the equivalent...
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