Alyani Ismail

Multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency spacing

We demonstrate a multiwavelength Brillouin-erbium fiber laser with double-Brillouin-frequency spacing. The wider channel spacing is realized by circulating the odd-order Stokes signals in the Brillouin gain medium through a four-port circulator. The circulated odd-order Stokes signals are amplified by the Brillouin gain and thus produce even-order Stokes signals at the output. These signals are then amplified by erbium gain block to form a ring-cavity laser. Ten channels with 0.174 nm spacing that are generated at 0.5 mW Brillouin pump power and 150 mW pump power at 1480 nm can be tuned from 1556 nm to 1564 nm. The minimum optical signal-to-noise ratio of the generated output channels is 30 dB with maximum power fluctuations of ±0.5 dB.

NOVEL COMPACT MICROSTRIP ULTRA-WIDEBAND FILTER UTILIZING SHORT-CIRCUITED STUBS WITH LESS VIAS

We present here a new pattern with compact size of Ultra Wideband (UWB) microwave filter. The filter is based on quarter-wave length short-circuited stubs model. We introduced here a new schematic model by extracting all parasitic elements such as T- junction and discontinuity in our new pattern of UWB filter. This new filter has minimal number of vias and improved frequency bandwidth, insertion loss and return loss. It is fabricated on RT Duroid 5880 with 0.508 mm of substrate thickness. The final dimension is measured as 21 mm × 14 mm. It is not only compact, but also delivers excellent scattering parameters with magnitude of insertion loss, |S21| lower than 0.85 dB and return loss better than −11.6 dB. The fractional bandwidth is 109% from 3.06 GHz to 10.43 GHz. In the pass band, the measured group delay varies in between 0.47 ns to 0.32 ns, showing stability with minimum variation of only 0.15 ns.

X-Band Trisection Substrate-Integrated Waveguide Quasi-Elliptic Filter

A narrowband trisection substrate-integrated waveguide elliptic filter with coplanar waveguide (CPW) input and output ports is proposed and demonstrated for X-band applications. The filter is formed by incorporating metallized vias in a substrate (RT/Duroid) to create cross-coupled waveguide resonators. The result is an attenuation pole of finite frequency on the high side of the passband, therefore exhibiting asymmetric frequency response. The fabricated trisection filter with a centre frequency of 10.05 GHz exhibits an insertion loss of 3.16 dB for 3% bandwidth and a return loss of -20 dB. The rejection is larger than 15 dB at 10.37 GHz.

Vertical-Edge-Based Car-License-Plate Detection Method

This paper proposes a fast method for car-license-plate detection (CLPD) and presents three main contributions. The first contribution is that we propose a fast vertical edge detection algorithm (VEDA) based on the contrast between the grayscale values, which enhances the speed of the CLPD method. After binarizing the input image using adaptive thresholding (AT), an unwanted-line elimination algorithm (ULEA) is proposed to enhance the image, and then, the VEDA is applied. The second contribution is that our proposed CLPD method processes very-low-resolution images taken by a web camera. After the vertical edges have been detected by the VEDA, the desired plate details based on color information are highlighted. Then, the candidate region based on statistical and logical operations will be extracted. Finally, an LP is detected. The third contribution is that we compare the VEDA to the Sobel operator in terms of accuracy, algorithm complexity, and processing time. The results show accurate edge detection performance and faster processing than Sobel by five to nine times. In terms of complexity, a big-O-notation module is used and the following result is obtained: The VEDA has less complexity by K2 times, whereas K2 represents the mask size of Sobel. Results show that the computation time of the CLPD method is 47.7 ms, which meets the real-time requirements.

X-band miniaturized wideband bandpass filter utilizing multilayered microstrip hairpin resonator

This paper presents a new design of miniaturized wideband bandpass fllter using microstrip hairpin in multilayer conflguration for X-band application. The strong coupling required for wideband fllter is realized by arranging flve hairpin resonators in two layers on difierent dielectric substrates. Since adjacent resonator lines are placed at difierent levels, there are two possible ways to change coupling strength by varying the overlapping gap between two resonators; vertically and horizontally. In this paper, simulated and measured result for a wideband fllter of 4.4GHz bandwidth at 10.2GHz center frequency with flfth order Chebyshev response is proposed. The fllter is fabricated on 0.254mm thickness R/T Duroid 6010 and R/T Duroid 5880 with dielectric constant 10.2 and 2.2 respectively using standard photolithography technique. Two fllter conflgurations based on vertical (Type 1) and horizontal (Type 2) coupling variation to optimize the coupling strength are presented and compared. Both conflgurations produce very small and compact fllter size, at 5:0 £ 14:6mm 2 and 3:2 £ 16:1mm 2 for the flrst and second proposed fllter type respectively. The measured passband insertion losses for both fllters are less than 2.3dB and the passband return loss is better than i16dB for fllter Type 1 and i13dB for fllter Type 2. Very small and compact fllter is achieved where measured results show good agreement with the simulated responses.

A CIRCULAR SYNTHETIC APERTURE RADAR FOR ON-THE-GROUND OBJECT DETECTION

Detecting an on-the-ground object is a subject of interest for use in some applications. Foreign Object Detection (FOD), which is an important issue in aviation safety, is a possible application. In this way, radar imaging, has several inherent advantages over other on-the-ground object detection techniques. This paper will introduce a ground-based Circular Synthetic Aperture Radar, which detects and localizes various objects, based on their re∞ection properties of microwaves. Here, wideband Linear Frequency Modulated (LFM) chirp pulses are employed for the transmission and reception of re∞ection pulses, both to and from the object under test. Once the pulses are received by the radar, a processing algorithm (proposed later in this paper) is executed to conflrm detection. In order to verify the validity of the model, a prototype was developed and a series of fleld experiments was carried out. The results show that the proposed system has the ability to detect and localize on-the-ground objects with dimensions as small as 2cm high and 1cm diameter, located several metres away. Furthermore, the resolution of the system was analysed and results indicate that the system is capable of distinguishing multiple objects in close proximity to each other, which therefore, makes it suitable for FOD applications by some small modiflcations.

An aligned-gap and centered-gap rectangular multiple split ring resonator for dielectric sensing applications

This paper presents the design and development of a planar Aligned-Gap and Centered-Gap Rectangular Multiple Split Ring Resonator (SRR) for microwave sensors that operates at a resonance frequency around 5 GHz. The sensor consists of a microstrip transmission line loaded with two elements of rectangular SRR on both sides. The proposed metamaterial sensors were designed and fabricated on Rogers RT5880 substrate having dielectric constant of 2.2 and thickness of 0.787 mm. The final dimension of the proposed sensor was measured at 35 × 14 mm2. Measured results show good agreement with simulated ones as well as exhibiting high Q-factor for use in sensing application. A remarkably shift of resonance frequency is observed upon introduction of several sample with different dielectric value.

All-optical generation of a 21 GHz microwave carrier by incorporating a double-Brillouin frequency shifter

An all-optical generation of a microwave carrier at 21 GHz that incorporates a double-Brillouin frequency shifter is presented. The frequency shift of approximately 21 GHz is achieved by generating the second-order Brillouin Stokes signal from the Brillouin pump. This is accomplished through the circulation and isolation of its first-order Stokes signal in the optical fiber. The Brillouin pump signal is heterodyned with its second-order Brillouin Stokes signal at a high-speed photodetector, and the output beating frequency is equal to the offset between these two signals. The generated microwave carrier is measured at 21.3968 GHz, and the carrier phase noise as low as -58.67 dBc/Hz is achieved.

Miniaturized Ultra-Wideband Antenna Using Microstrip Negative Index Metamaterial

Abstract A three left-handed metamaterial unit cell antenna is presented in this article for ultra-wideband applications. Each left-handed metamaterial unit cell is a combination of a modified octagonal split-ring resonator, an octagonal spiral resonator, a capacitance-loaded strip, and a wire in order to achieve a design that simultaneously exhibits both negative electrical permittivity and negative magnetic permeability, which promises an extraordinary index of negative refraction to enhance the radiated power of the antenna, consequently improving the antenna system. The antenna design was etched on an FR4 epoxy substrate (Farnell Electronic Components Limited, Selangor D.E., Malaysia) with an evident compact size of 25 × 25 × 1.6 mm 3 . Return loss measurements demonstrated that this antenna achieves 94% bandwidth for a voltage standing wave ratio less than 2 over the frequency band of 5.2–13.9 GHz, with a maximum gain and directivity of 3.85 dBi and 5.45 dB, respectively, at 10.5 GHz. These measurement results show good agreement with those of the simulations as well as good omni-directional characteristics within its operating frequency band. The proposed metamaterial antenna is compact and highly directive and has a tunable operational frequency especially for ultra-wideband applications.

Novel compact "via-less" ultra-wide band filter utilizing capacitive microstrip patch

This paper presents a novel compact “via-less” UWB filter derived from a quarter-wavelength short-circuited stubs model. In this compact “via-less” UWB filter, there is no connecting vias as short circuit elements. Unlike its previous model that has 5 short-circuited stubs, this novel shape consists of two pairs of stubs which are joint together to share on the same microstrip patch and thus reduces total size of the UWB filter itself making it more compact in nature. With proper width optimization, the microstrip patch is able to decouple and provides low impedance to the ground in the UWB frequencies range. The filter delivers 3.85GHz to 10.44 GHz frequency range with 92.23% of fractional bandwidth. The magnitude of insertion loss is below than 0.53 dB and the return loss is lower than −14.8dB in the passband frequencies. The −3 dB bandwidth is from 3.85 GHz to 10.44 GHz with 92.23% of fractional bandwidth. The group delay only varied by 0.47 ns in the passband, which makes it suitable for radio communication systems.