A.M. Abbosh

University of Queensland, Brisbane, Queensland, Australia

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Publications (286)187.44 Total impact

  • Ahmed Toaha Mobashsher · A. Mahmoud · A. M. Abbosh
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    ABSTRACT: Intracranial hemorrhage is a medical emergency that requires rapid detection and medication to restrict any brain damage to minimal. Here, an effective wideband microwave head imaging system for on-the-spot detection of intracranial hemorrhage is presented. The operation of the system relies on the dielectric contrast between healthy brain tissues and a hemorrhage that causes a strong microwave scattering. The system uses a compact sensing antenna, which has an ultra-wideband operation with directional radiation, and a portable, compact microwave transceiver for signal transmission and data acquisition. The collected data is processed to create a clear image of the brain using an improved back projection algorithm, which is based on a novel effective head permittivity model. The system is verified in realistic simulation and experimental environments using anatomically and electrically realistic human head phantoms. Quantitative and qualitative comparisons between the images from the proposed and existing algorithms demonstrate significant improvements in detection and localization accuracy. The radiation and thermal safety of the system are examined and verified. Initial human tests are conducted on healthy subjects with different head sizes. The reconstructed images are statistically analyzed and absence of false positive results indicate the efficacy of the proposed system in future preclinical trials.
    No preview · Article · Feb 2016 · Scientific Reports
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    Ali Zamani · Amin M. Abbosh · Ahmed Toaha Mobashsher
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    ABSTRACT: A multistatic microwave imaging technique is presented for fast diagnosis of medical emergencies pertaining to brain injuries. The frequency-based imaging method utilizes Bessel functions to estimate the scattered power intensity inside the imaged region from measured multistatic scattered signals outside the imaged region in a quasi-real-time manner. A theory is used to prove that the relation between the scattered fields outside the imaged object (the head) and the internal scattering profile follows the first order of first type Bessel function. To reconstruct the internal scattered power intensity accurately, the average-trace subtraction method is used to remove the skin reflections and clutters. The presented algorithm is verified using realistic numerical simulations and experimental measurements, which are performed using a radar-based head imaging system that includes an antenna array containing eight elements, microwave transceiver, and switching network. To emulate different brain injuries, realistic head phantoms are utilized. The obtained results using frequency steps that meet Nyquist criterion confirm the reliability of the proposed method in the successful detection of different sizes and locations of injuries inside the head phantom in a fast and consistent way. In comparison with existing multistatic time-domain methods, the presented approach is faster and more accurate.
    Full-text · Article · Jan 2016 · IEEE Transactions on Microwave Theory and Techniques
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    Ahmed Mobashsher · Amin Abbosh
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    ABSTRACT: Researchers have proposed numerous wideband antennas with directional or omnidirectional radiations to meet the requirements of microwave based head imaging systems. This paper aims to study the effect of directionality on image quality of those systems. Hence, both directional and omnidirectional wideband antennas are designed and prototyped. Both antennas cover a wide bandwidth (1.25-2.4 GHz) which is typically used in microwave head imaging and attain a boresight average gain of 3.5 dBi. The antennas’ near-field radiation patterns are measured and analyzed. The antennas’ transient pulse performance in the near-field region along boresight direction is also studied. It is observed that without the effects of multipath inside the head, the directional antenna provides 20% higher impulse fidelity and 4 dB more peak transient response than the omnidirectional antenna. An experimental verification is examined by imaging a realistic artificial head phantom with an emulated brain injury. Quantitative analysis of the reconstructed images demonstrates that directional antenna yields more focused images with low artifacts than omnidirectional antenna.
    Full-text · Article · Jan 2016 · IEEE Antennas and Wireless Propagation Letters
  • He Zhu · Amin M. Abbosh
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    ABSTRACT: A tunable balanced bandpass filter using a short coupled-line resonator is proposed. The design aims at achieving a wide tuning range in the differential-mode for both of the center frequency and bandwidth with high common-mode suppression. The proposed filter uses a short section (about one-eighth of one wavelength) of parallel-coupled lines connecting the differential ports of the device and five pairs of varactors. A theoretical analysis using the even-odd mode theory is presented to verify the tunability of the design and calculate the initial values of its design parameters. For validation, a prototype is designed, fabricated and tested. The measured results indicate that the differential-mode tuning range for the center frequency and 3 dB- bandwidth extend from 0.58 to 1.22 GHz, and from 65 to 180 MHz, respectively, with more than 30 dB of common-mode suppression in the operating differential-mode passband. Moreover, the proposed device has a compact size (with respect to the guided wavelength) of only 0.12λG×0.08λG .
    No preview · Article · Dec 2015 · IEEE Microwave and Wireless Components Letters
  • Jayaseelan Marimuthu · Amin M. Abbosh · Bassem Henin
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    ABSTRACT: A compact third order bandpass filter (BPF) using dual and trimode resonators is proposed. To achieve compact size with wide and highly attenuated stopband with achievable fractional bandwidth (FBW), the proposed filter is designed using a dual-mode resonator in the form of a low-impedance feeding network and a trimode resonator formed using a miniaturized (one twelfth of a wavelength) parallel-coupled structure loaded with folded open-ended stubs of high/low-impedances and a semiannular resonator. To enable using easy to manufacture dimensions, the coupled structure of the resonator is designed to have moderate mode impedances. A complete design procedure for the filter is explained. Finally, a compact penta-mode BPF with 35% FBW with sharp upper and lower cutoffs is built and tested. The simulated and measured performance of the filter show less than 0.3 dB insertion loss in the passband and more than 32 dB attenuation across a wide stopband with sharp upper (107 dB/GHz) and lower cutoff (96 dB/GHz) skirts. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2824–2829, 2015
    No preview · Article · Dec 2015 · Microwave and Optical Technology Letters
  • A.M. Abbosh · U.T. Ahmed
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    ABSTRACT: A broadband out-of-phase power divider in a compact structure employing a microstrip technology is presented. The proposed power divider consists of a T-junction of microstrip to slotline transition at the input ports along with a pair of tightly coupled microstrip lines at the two output ports. The main features of the proposed device are the employment of a dumbbell-shaped slot terminated with a chip resistor under the tightly coupled lines to improve the isolation between the output ports and shunt open-ended stubs at the output ports to improve their impedance matching. The overall size of the structure is 30 × 60 mm using the substrate Rogers RO4003C with a dielectric constant of 3.38 and thickness of 0.4 mm. The simulated and experimental results of the developed device show wide bandwidths (120% fractional bandwidth) with isolation >15 dB across the investigated band 1-4 GHz. In addition, the output ports are out-ofphase with <1° phase imbalance across the whole frequency band.
    No preview · Article · Nov 2015 · Electronics Letters
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    A. T. Mobashsher · A. M. Abbosh
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    ABSTRACT: Time-domain characterisation is vital in verifying the suitability of wideband antennas for near-field applications such as microwave medical imaging and sensing. To that end, a near-field time-domain characterisation method to calculate the near-field transient response and the distortion of wideband antennas is proposed. The method uses a pulse merit factor, which consists of the near-field timedomain signal amplitude and a fidelity factor, both normalised to the highest values attained from the antennas. To verify the method, the transient responses of unidirectional and omnidirectional antennas designed for near-field imaging are analysed. The analyses show that even though the investigated antennas cover the same band with the same average far-field gain along the boresight direction, the unidirectional antenna exhibits 35% more pulse merit factor with less impulse distortion along the intended direction, which suggests better suitability for wideband near-field imaging systems.
    Full-text · Article · Nov 2015 · Electronics Letters
  • Ali Zamani · Amin Abbosh
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    ABSTRACT: The accuracy of microwave head imaging is adversely affected by strong clutters that can completely mask the target response. To that end, different clutter removal techniques are modified for multistatic frequency-based imaging. It is shown that some deficiencies of those methods in time domain, such as time overlapping, can be alleviated when they are modified for use in frequency domain. Based on the explored performance of different methods in the frequency domain, a hybrid technique, which combines the benefits of average subtraction and entropy-based filtering methods, is proposed. In this method, the average value of the multistatic scattered signals is subtracted from them at each frequency sample to remove late-stage clutters, whereas an entropy-based method is applied to mitigate early-stage strong clutters. The proposed technique is verified in realistic environments using simulations and experiments. The utilized system for verification is 1.1-3.2 GHz frequency-domain multistatic with an eight-element antenna array, and compact microwave transceiver. The simulations are performed on MRI-derived head model, whereas the experiments are done on realistic artificial head phantom. The obtained results from different locations and sizes of emulated brain injuries confirm the effectiveness of the proposed method in producing high quality images of the head after mitigating the clutter.
    No preview · Article · Nov 2015 · IEEE Transactions on Antennas and Propagation
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    ABSTRACT: A foam-embedded wideband antenna array is used to build a portable system for congestive heart failure (CHF) detection. In addition to the array, which has a pair of four-element antenna subarrays, the system includes a portable vector network analyzer (VNA), a switching system, and a laptop, which contains control, signal processing, and image formation algorithms. The main aim of the built system is to provide a noninvasive, convenient, low cost, fast, and reliable platform for detection and monitoring of CHF. In that regard, the antenna elements are built using a three-dimensional (3-D) structure, which utilizes a combination of loop, monopole, and parasitic patches to cover the needed band (0.7-1 GHz) while keeping the size compact. A differential technique is utilized to distinguish between healthy and unhealthy cases. The performance of the system is tested on an artificial phantom and a phantom with a pair of lamb lungs, which are confirmed to have electrical properties close to those of humans. Several possible cases are investigated to validate the reliability of the system in the early detection of CHF.
    No preview · Article · Nov 2015 · IEEE Transactions on Antennas and Propagation
  • A.M. Abbosh · U.T. Ahmed
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    ABSTRACT: A planar microwave in-phase power divider operating over threeoctave frequency band is presented. The proposed device is composed of two main parts. The first one is a pair of microstrip-slotline-microstrip transitions introduced to match the impedances at the input port. The second one is a pair of loosely coupled microstrip lines with two isolation resistors to provide improved isolation performance at the output ports over a wide range of frequency band. The device has a compact area of 40 × 40 mm using the substrate RO4003C (dielectric constant of 3.38 and thickness of 0.406 mm). The simulated and experimental results of the developed device show three-octave bandwidths (155% fractional bandwidth) with isolation <15 dB across the investigated band from 1 to 8 GHz. In addition, the device provides a < ±2° differential phase between the in-phase output ports across the whole frequency band.
    No preview · Article · Oct 2015 · Electronics Letters
  • K.S. Bialkowski · A.M. Abbosh · B.J. Mohammed
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    ABSTRACT: In radar-based time-domain head imaging, a priori information on the effective dielectric constants from the antennas' perspective with respect to different head pixels is needed to map the significant scatterrers inside the head. A microwave-based head imaging technique, which utilises a model for the effective dielectric constant as a function of the antenna's position and imaged point inside the head, is presented. To build that model, a realistic MRI-derived numerical head surrounded by an array of wideband antennas is implemented in a full-wave electromagnetic solver. The time difference of arrival between transmission coefficients in free space and inside the head is calculated at different head pixels and used to evaluate the effective dielectric constant at those pixels. The model is validated on two different head phantoms and used to accurately detect different brain strokes.
    No preview · Article · Sep 2015 · Electronics Letters
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    A.M. Abbosh · A. Zamani · Ahmed Toaha Mobashsher
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    ABSTRACT: In many medical applications, getting an accurate detection in real, or at least quasi-real, time is vital for the survival of the patient. An example of such an application is the detection of brain injuries due to different accidents. In this work, a frequency-domain multistatic microwave imaging technique, which aims to serve medical applications that require fast diagnosis, is explained. The method employs the captured multistatic scattered signals around the imaged domain to predict the scattering profiles inside that domain in a quasi-real-time manner. For an accurate reconstruction of the internal scattering profile, the method employs a proper technique to cancel background clutter and skin interface reflections. It is successfully verified using full-wave electromagnetic simulations in the detection of brain injury, which is one of the challenging applications of microwave imaging. To that end, a realistic radar-based simulation environment that includes an 8-element antenna array is used to detect brain injuries in a realistic head phantom. Index Terms— Head imaging, microwave imaging, frequency domain imaging, multistatic radar imaging
    Full-text · Conference Paper · Sep 2015
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    ABSTRACT: Pulmonary oedema is a common manifestation of various fatal diseases that can be caused by cardiac or non-cardiac syndromes. The accumulated fluid has a considerably higher dielectric constant compared to lungs' tissues, and can thus be detected using microwave techniques. Therefore, a non-invasive microwave system for the early detection of pulmonary oedema is presented. It employs a platform in the form of foam-based bed that contains two linear arrays of wideband antennas covering the band 0.7-1 GHz. The platform is designed such that during the tests, the subject lays on the bed with the back of the torso facing the antenna arrays. The antennas are controlled using a switching network that is connected to a compact network analyzer. A novel frequency-based imaging algorithm is used to process the recorded signals and generate an image of the torso showing any accumulated fluids in the lungs. The system is verified on an artificial torso phantom, and animal organs. As a feasibility study, preclinical tests are conducted on healthy subjects to determinate the type of obtained images, the statistics and threshold levels of their intensity to differentiate between healthy and unhealthy subjects.
    Full-text · Article · Sep 2015 · Scientific Reports
  • Ummee T. Ahmed · Amin M. Abbosh
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    ABSTRACT: The design of a planar out‐of‐phase power divider with broadband behavior is presented. The proposed device uses broadside coupled microstrip‐slotline‐microstrip transitions at the input port and coupled microstrip lines with shunt open‐ended stubs at the output ports to extend the impedance matching bandwidth at three ports of the device. Moreover, a dumbbell‐shaped slot is located underneath the coupled lines and shunted with a proper chip resistor to improve the isolation between the output ports. The utilized structure is suitable for single layer integration as both the input and output ports are located at the same layer. Following a proper theoretical method based on the even‐odd mode approach and slotline design guidelines, a prototype of the presented device aiming to operate across the band 1–3 GHz is designed, built, and tested. The developed device has overall dimensions of 30 mm × 60 mm using the substrate Rogers RO4003 (dielectric constant = 3.38 and thickness = 0.406 mm). While the device can be used for any wideband application, the developed prototype is designed to operate within the band 1–3 GHz, which is used in most microwave‐based medical imaging applications. The achieved simulated and experimental results show 100% fractional bandwidth (1.1–3.3 GHz) assuming 15 dB of isolation as the reference. The proposed device has equal power division between the two output ports with less than 0.2 dB amplitude imbalance. Moreover, the phase difference between the signals at the two output ports is 180° ± 1° across the frequency band 1–3.5 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2216–2218, 2015
    No preview · Article · Sep 2015 · Microwave and Optical Technology Letters
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    ABSTRACT: A technique for noninvasive microwave hyperthermia treatment for breast cancer is presented. In the proposed technique, electromagnetic focusing on patient-specific breast models is implemented to concentrate the power at the tumor position while keeping the power levels at other positions (healthy tissues) at minimum values. This step is realized by optimizing phase excitations of the utilized antenna elements. In the next step, a thermal analysis is used to determine the scaling factor of the antennas’ excitation amplitudes to realize the required temperature at the tumor position. A closed-loop procedure ensures that there are no hot spots in any of the healthy tissues. The technique is tested in a realistic environment which includes three-dimensional breast models and antenna arrays. The presented results on fatty and dense breast models using two types of directional antennas validate the proposed technique. The investigations across wide frequency bands indicate that the frequencies around 4.2 GHz and 4.5 GHz are optimum values for the hyperthermia treatment of dense and fatty breasts, respectively.
    No preview · Article · Aug 2015 · IEEE Transactions on Antennas and Propagation
  • Lei Guo · Amin M. Abbosh
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    ABSTRACT: An optimization-based confocal algorithm for microwave imaging aimed at medical applications is presented. Due to complexity of human body tissues, microwave signals that enter a human organ from different angles and are reflected at different depths inside that organ face different effective dielectric constants. An accurate estimation of those dielectric constants is vital for an accurate estimation of signal speed within the imaged object and thus accurate resultant images. The traditional confocal algorithm uses one preassumed effective dielectric constant and thus its resultant image is sensitive to that assumption. In the proposed approach, position-dependent dielectric constants are used to generate a highly focused image that accurately maps scatterers within an imaged object. To that end, an objective equation based on the focusing degree of the obtained initial image is created. Then, particle swarm optimization (PSO) uses that equation to find the effective dielectric constants facing signals penetrating the object according to their entrance point. Those optimized effective dielectric constants are used to produce a highly focused image without the risk of creating false-positive targets irrespective of the initial values of the effective dielectric constants. The proposed algorithm is evaluated in head imaging via full-wave electromagnetic simulations and experiments. The simulations are based on using an accurate numerical head model, whereas the experiments are conducted using realistic artificial head phantoms. The obtained images indicate that the quality of the images is significantly improved with more accurate localization of targets in unhealthy cases and less probability of positive false alarms in healthy cases compared with the traditional approach.
    No preview · Article · Aug 2015 · IEEE Transactions on Antennas and Propagation
  • U. T. Ahmed · A. M. Abbosh
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    ABSTRACT: A planar in-phase power divider with extreme wideband behavior using modified Wilkinson design is presented. Instead of using T-junction at the input port of the traditional design, the proposed divider uses broadside coupled microstrip to slotline configuration. Moreover, the impedance matching of the output ports is significantly improved across several octaves bandwidth using three binomial sections, whereas the isolation between those ports is enhanced across that band using three isolation resistors. The utilized structure is suitable for single layer integration as both the input and output ports are located at the same layer. A prototype of the presented device is designed using a proper theoretical approach, built, and tested. The developed device has a compact size with an overall dimension of 40 × 55 mm2 using the substrate Rogers RO4003 (dielectric constant = 3.38, thickness = 0.406 mm). While the device can be used for any wideband application, the developed prototype is designed to operate within the band 1–7 GHz, which is used in most microwave-based medical imaging applications. The achieved simulated and measured results show that the proposed device has equal power division between the two output ports with less than 0.2-dB amplitude imbalance, more than 10-dB return loss and 15-dB isolation, and less than 2° phase difference between the two output signals across the extremely wide frequency band 1.2–7 GHz. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1799–1802, 2015
    No preview · Article · Aug 2015 · Microwave and Optical Technology Letters
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    ABSTRACT: Pleural effusion (PE) is the accumulation of fluids around the lungs due to various diseases, such as cancer, liver and heart failure. Given the fact that fluid provides a high contrast in terms of dielectric constant at microwave frequencies, a radar-based microwave imaging system is proposed to utilise that change in properties for the early detection of PE. The system uses a wideband slot-loaded loop antenna to scan the torso, a portable vector network analyser for signal generation and recording, and a laptop for signal processing and image formation using a frequency-based imaging algorithm. The utilised antenna is designed to have a compact size (in wavelengths) of 0.23 × 0.23 that is one-third the size of recent designs. By using proper slots in a conventional slot-loaded loop and adding a staircase-shaped patch to the loop's perimeter, the antenna achieves a fractional bandwidth of 50% (0.72-1.19 GHz), and a peak gain of 4.9 dBi. The practicality of the proposed system is successfully tested by detecting a small amount of fluid (3 mL) around the lungs of a realistic life-size torso phantom.
    No preview · Article · Jul 2015 · Electronics Letters
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    Ahmed Toaha Mobashsher · A M Abbosh
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    ABSTRACT: Portable head imaging systems spurs on new designs of compact antennas having ultra-wideband (UWB) operation with unidirectional radiation patterns in the low microwave frequencies. This paper describes the limitations of previously designed three-dimensional (3D) antennas proposing a more compact antenna with 79% fractional bandwidth with stable directional radiation patterns. At least 50% size reduction compared to the previous proposed antennas is achieved enabling utilization of more elements in the antenna array of the imaging system.
    Full-text · Conference Paper · Jul 2015
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    ABSTRACT: A slot-loaded meandered loop antenna for congestive heart failure (CHF) detection system is presented. To meet the requirements for a CHF detection system, the antenna is designed to have a compact size, wideband at the ultra-high frequency band and unidirectional radiation. To that end, several techniques are applied to the main utilized structure, which is a conventional loop antenna. To lower the resonant frequency and enhance the directivity within a compact size, the loop is capacitively loaded using a pair of slots. To compensate for the effect of the capacitive coupling on the input impedance matching, an inductive reactance is added by meandering the loop’s structure. With the applied modifications, the proposed antenna has a compact size of ${0.21} times 0.21$ with respect to the wavelength at the lowest operating frequency. The realized dimension represents only a quarter of the size of its counterpart planar designs. The proposed antenna achieves a wide measured fractional bandwidth of 50% (0.66–1.1 GHz), 9 dB peak front-to-back ratio and 4.1 dBi gain. The antenna is then used as part of a CHF detection system that also includes a compact transceiver, scanning platform, and laptop for control and processing. Using a suitable frequency–domain processing and imaging algorithm, the system successfully detects an early CHF in an artificial torso phantom.
    No preview · Article · Jul 2015 · IEEE Transactions on Antennas and Propagation

Publication Stats

2k Citations
187.44 Total Impact Points

Institutions

  • 2005-2015
    • University of Queensland
      • School of Information Technology and Electrical Engineering
      Brisbane, Queensland, Australia
  • 2006-2010
    • Griffith University
      • • Centre for Wireless Monitoring and Applications
      • • School of Engineering
      Southport, Queensland, Australia
  • 2006-2009
    • University of Mosul
      • • College of Electronic Engineering
      • • Department of Electrical Engineering
      Mosul, Muhafazat Ninawa, Iraq