Browsing by Author "Nawaz, Wasim"

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A compact circularly polarized monopulse slotted waveguide array for airborne applications
(2019-10-24) Nawaz, Wasim; Uysal, Murat; Uysal, Murat; Durak, Kadir; Akgiray, Ahmet; Adam, Evşen Yanmaz; Güçlüoğlu, T.; Department of Electrical and Electronics Engineering; Nawaz, Wasim
In modern radar and communication systems, high gain, high power capability and low-profile antenna systems are frequently utilized. In airborne and space borne applications, slotted waveguide antenna array is widely used due to its rigid structure, low-loss and high power handling capability. In this thesis, a compact, lightweight, high reection bandwidth, high gain and circularly polarzied slotted waveguide array antenna with monopulse capability operating in Ku-band is presented. Target application of this antenna is radio links on airborne platforms with built-in tracking capability . This thesis is divided into two parts: 1) Design of compact standing wave slotted array; 2) Design of a low-cost linear polarization (LP) to circular polarzition (CP) converter. In the first part of thesis, an antenna system is presented that has two key components: monopulse comparator/feed network and antenna section. The antenna is designed at 15 GHz and simulated using ANSYS HFSS. It is a planar array of 6x8 radiating slots with a gain greater than 22:5 dB at 15 GHz , side-lobe level (SLL) 13 dB , reection bandwidth of 1200 MHz. Monopulse comparator network is Magic Tee based waveguide structure. The antenna has maximum dimension of 10:8 cm * 10:7 cm 4 cm that makes it easy to house on an aircraft. In the second part of thesis, a LP to CP polarizer is presented. The proposed polarizer is a multi-layer metasurface based structure that converts incident linearly polarized wave into circularly polarized wave. The polarizer presented in this thesis is based on meander line and strip line hybrid concept. Each substrate layer is rotated 45 with respect to previous layer and is seperated by low permittivity material called spacer. The unit cell of the polarizer is square in shape with dimensions of 5:1mm 5:1 mm. Its axial ratio bandwidth is 2 GHz i.e: axial ratio is less than 3-dB from 14-16 GHz . It is also low-cost as compared to the available literature because thick substrates are used instead of high cost thin substrate and also one substrate layer is based on FR-4 laminate.
Open Access
Design and analysis of a truncated elliptical-shaped chipless RFID tag
(TÜBİTAK, 2021) Khan, A. T.; Abdullah, Y.; Farhat, S.; Nawaz, Wasim; Rauf, U.; Nawaz, Wasim
This article presents a novel polarization-insensitive chipless radio frequency identification tag having an encoding capacity of 11 bits. The proposed resonator design comprises discontinuous arc slots forming truncated elliptically shape offering 1:1 slot to bit correspondence with suppressed unwanted harmonic resonances. Electromagnetic performance analysis of the proposed tag design is done over an ungrounded Rogers RT duroid® 5880 laminate. The overall tag design covers a footprint of 15 × 15 × 0.508 mm 3 offering convincingly appreciable bit density of 4.88 bits/cm 2. The realized tags are analyzed for real-world electromagnetic performance resulting in an agreement between measured and computed results. The proposed work finds its applications in the food and beverage industry.
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Design of compact monopulse standing wave slotted array in ku-band
(IEEE, 2019) Akgiray, Ahmed Halid; Nawaz, Wasim; Electrical & Electronics Engineering; AKGİRAY, Ahmed Halid; Nawaz, Wasim
In modern radar and communication systems, high gain, high power capability and low-profile front-end antenna systems are frequently utilized. In this paper, a compact, lightweight, high reflection bandwidth and high gain slotted wave guide array antenna with monopulse capability operating in Ku- band is presented. Target application of this antenna is radio links with built-in tracking capability on airborne platforms. The presented system is simulated using ANSYS HFSS and has two key components: monopulse comparator/feed network and antenna section. The antenna is designed at 15 GHz and it is a planar array of 4×8 radiating slots with a gain greater than 21 dB at 15 GHz, side-lobe level (SLL) ≤ -13 dB, reflection bandwidth of 1062 MHz. Monopulse comparator network is planar Magic Tee based waveguide structure. The complete integrated system has maximum dimension of 12cm x 7.2cm x 4cm that makes it easy to house on an aircraft.
Metadata only
Low-cost thin-film passive RFID circuits and detector system
(Cambridge University Press, 2020-06) El-Sawy, Salma; Nawaz, Wasim; Abouzeid, Mohamed Osama Hussein Soliman; Tekin, Ahmet; Electrical & Electronics Engineering; TEKİN, Ahmet; El-Sawy, Salma; Nawaz, Wasim; Abouzeid, Mohamed Osama Hussein Soliman
This paper discusses the design of chip-less RFID tags of a standard pocket size of 69 mm by 156 mm. These tags are based on lumped elements of copper metal traces constructed on a thin polyamide flexible substrate. Moreover, a low-cost single-chip Bluetooth detector circuit system is demonstrated. Two different detection methods: variable coil load coupling and optical light intensity detection were combined to yield 256 unique ID codes. In the first method, by utilizing simple 4 MHz digital drivers and an integrated analog to digital converter (ADC) in the reader controller; various inductively coupled resonant loads corresponding to multiple distinct tags could be differentiated, yielding eight different (3-bit) ID codes. The additional via-based hole pattern reflectometer method creates additional 32 distinct levels (5-bit) utilizing 650 nm visible light-emitting diode and a simple trans-impedance operational along with the same analog ADC pins of a Bluetooth controller. The printed circuit board trace coil on the two-layer low-cost FR-4 waterproof sealed detector unit is simultaneously used as a Qi wireless power receiver to charge the120 mAh 2450 Lithium Polymer (LiR) battery. The device could remain operational for more than a month with a single charge; remaining connected with a mobile device and enabling 10 readouts daily.