Space scanning FMCW-based two-dimensional frequency diverse array radar

The frequency-modulated continuous wave (FMCW)-based frequency diverse array (FDA) radar concept is extended to two dimensions (2D). The radar operates as a linear pulsed FMCW/FDA in the transmission (TX) mode while it operates as a pulsed FMCW/phased array (PA) in the receiving mode. It is shown that the FDA has the capability of scanning a 2D angular sector in a single pulse TX. It is shown that local instantaneous frequency bandwidth is much smaller than the radiofrequency (RF) frequency deviation of linear frequency modulation. Positive and negative slope TX/RF locations offer frequency diversity. The low signal-to-noise ratio of FDA is well compensated due to target temporal decorrelation diversity in the observation time and by the cumulative detection scheme used. Time domain and frequency domain signal processings are described. A Kuband direct digital synthesis-based FDA radar design is compared by a corresponding equivalent PA radar

Does “Hidden Undercuffing” Occur Among Obese Patients? Effect of Arm Sizes and Other Predictors of the Difference Between Wrist and Upper Arm Blood Pressures

J Clin Hypertens (Greenwich). 2010;12:82–88. © 2009 Wiley Periodicals, Inc. Arm size can affect the accuracy of blood pressure (BP) measurement, and “undercuffing” of large upper arms is likely to be a growing problem. Therefore, the authors investigated the relationship between upper arm and wrist readings. Upper arm and wrist circumferences and BP were measured in 261 consecutive patients. Upper arm auscultation and wrist BP was measured in triplicate, rotating measurements every 30 seconds between sites. Upper arm BP was 131.9±20.6/71.6±12.6 mm Hg in an obese population (body mass index, 30.6±6.6 kg/m 2 ) with mean upper arm size of 30.7±5.1 cm. Wrist BP was higher (2.6±9.2 mm Hg and 4.9±6.6 mm Hg, respectively, P <.001); however, there was moderate concordance for the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) strata (κ value=0.27–0.71), and the difference was ≥5 mm Hg in 72% of the patients. The authors conclude that there was poor concordance between arm and wrist BP measurement and found no evidence that “hidden undercuffing” was associated with obesity; therefore, they do not support routine use of wrist BP measurements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78621/1/j.1751-7176.2009.00222.x.pd

Prospects of FMCW-based frequency diverse array radar

The linear frequency modulated (LFM) frequency modulated continuous wave (FMCW)-based frequency diverse array (FDA) radar concept is investigated in detail. The radar operates as a linear pulsed FMCW/FDA in the transmission (TX) mode while it operates as a pulsed FMCW/phased array (PA) in the receiving mode. The issues such as low signal-to-noise ratio (SNR) of FDA, the time-angle scanning and time-range ambiguities are studied. It is shown that the local instantaneous frequency bandwidth is much smaller than the radio frequency (RF) deviation of LFM. Positive and negative slope TX/RF locations offer frequency diversity. Time domain and frequency domain signal processings are described. A Ku band direct digital synthesis-based FMCW/FDA radar example based on the cumulative detection scheme is given and compared with an equivalent FMCW/PA radar

Bilgi toplumu teknolojileri için anten sistemleri ve algılayıcılar

TÜBİTAK EEEAG01.10.2010Bu proje kapsamında, özellikle milimetre-dalga frekanslarında çalışan yeniden şekillendirilebilir anten, elektronik taramalı dizi anten ve yansıtıcı dizi anten tasarımı, üretimi ve ölçümleri yapılmıştır. Yeniden şekillendirilebilirlik özelliği için farklı teknolojiler kullanılmıştır. Huzmesi yönlendirilebilen sur biçimli mikroşerit yürüyen dalga anten dizisi X-bant uygulamalarında kullanılmak üzere tasarlamış, üretilmiş ve ölçülmüştür. Antenin ana huzmesinin istenilen yöne elektronik olarak döndürülebilmesini sağlayabilmek için mikroşerit hat üzerinde gerekli faz değişimini sağlayacak varaktör diyotlar kullanılmıştır. Yapılan EM benzetim ve ölçümler sonucu sur biçimli anten dizisinde, ana huzmenin diyot kontrolü ile tasarlandığı gibi 10 lik bir açı taraması yapabildiği gösterilmiştir. Bu kavram kanıtlaması şeklinde bir çalışmadır; huzmenin daha büyük açı aralığında tarama yapması için tasarımda yapılması gereken değişiklikler belirtilmiştir. MM-Dalga sabit genişlikli ve doğrusal sönümlenen yarık antenler tasarlanıp, üretilmiş ve antenin şeklinin, optik uyarımla bu iki yapı arasında değiştirilmesinin sağlanması durumunda ışıma örüntüsünün değiştirilebileceği gösterilmiştir. Proje kapsamında gerçekleştirilen bir diğer çalışmada da K ve Ka bantlarında bağımsız çalışabilen, RF MEMS anahtarlarla huzmesi elektronik olarak döndürülebilen dairesel polarizasyonlu yansıtıcı dizi anten tasarlanmış, üretilmiş ve ölçülmüştür. Çift frekanslı (24.4 GHz ve 35.5 GHz) dizi iç içe geçmiş farklı boyutlarda iki ayrık-halka dizisi şeklinde tasarlanmıştır. Huzme döndürme amacıyla her bir ayrık halkanın açısal konumunu RF MEMS anahtarlarla ayarlayarak, dairesel polarizasyonlu dalgaların fazları kontrol edilmektedir. Anten ODTÜ MEMS merkezinde geliştirilen yüzey mikro-işleme süreciyle üretilmiştir. Işıma örüntüleri ölçülmüş ve benzetim sonuçlarıyla karşılaştırılmıştır. Ölçümlerle, ana huzmenin, tasarlandığı gibi, Ka bandında 35°‟ye, K bandında 24°‟ye döndürülebildiği gösterilmiştir. Proje çalışmalarından sur biçimli mikroşerit anten dizisiyle ilgili hazırlanan makale Microwave and Optical Technology Letters adlı dergide yayınlanmak üzere kabul edilmiştir. Yansıtıcı dizi antenle ilgili makale de hazırlık sürecindedir. Saygın konferanslarda yedi bildiri sunulmuştur. Ayrıca, proje kapsamında üç yüksek lisans tez çalışması tamamlanmıştır.In this project, reconfigurable antenna, beam steering array and reflectarray have been designed, produced and measured, especially in mm-wave frequencies. To provide reconfigurability, different technologies have been considered. X-band electronically scanning meanderline microstrip traveling wave antenna array has been designed, produced and measured. To rotate the antenna beam to the desired direction, microstrip meander line has been loaded by varactor diodes that provide required phase shift values. EM simulations and rdiation pattern measurements of the meanderline antenna have demonstrated that the antenna has the capability to scan 10 with the control of varactors as designed. This is a proof-of-concept type study; alternative configurations to increase the scan range have also been discussed. MM-wave tapered slot antennas with a constant width and linear taper have been designed, produced and measured. It has been demonstrated that if the shape of the tapered slot antenna can be changed between constant width and linear taper structures by means of optical excitation, radiation pattern reconfigurability can be obtained. In another study accomplished in this project, electronically scanning circularly polarized reflectarray working independently in K and Ka bands has been designed, produced and measured. Dual band (24.4 GHz and 35.5 GHz) reflectarray has been designed as an interlaced array of split rings of two different sizes. In order to steer the beam, the phase of the incident circularly polarized wave is controlled by RF MEMS switches that modify the angular orientation of split-rings individually. The antenna has fabricated by using surface micromachining process developed in METU MEMS Center. Radiation patterns of the antenna are measured and compared with the simulations. It has been shown that the reflectarray is capable of beam switching to 35° in Ka band, 24° in K band as required. One journal paper on meanderline antenna has been accepted to be published in Microwave and Optical Technology Letters. Preparation of manuscript on reflectarray is under progress. Seven conference papers have been presented in well known Conferences. Furthermore, three Master Thesis studies have been accomplished during the project

A new approach to use of the multipole expansion method in eletromagnetic scattering problems.

Ph.D. - Doctoral Progra

Sevofluran ve izofluranın günübirlik (outpatient) anestezi uygulamalarında derlenme ile mental ve psikomotor fonksiyonlar üzerine etkileri

TEZ2641Tez (Uzmanlık) -- Çukurova Üniversitesi, Adana, 1998.Kaynakça (s. 32-39) var.v, 39 s. ; 30 cm.

Pulsed FMCW waveform design for LPI radars based on stretch processing

An FMCW radar waveform design based on stretch procesing is described. Transmit (TX) and Receive (RX) functions are separated in time. A single antenna with no isolation problems can be used. A rigorous analysis of coherent processing is presented. Advantages and disadvantages are discussed. Compared to Pulsed Doppler Radar (PDR) this waveform has significant LPI properties. A generic design example is also given. © 2012 EUROPEAN MICROWAVE ASSOC

An Inverted L-Shape Fed Microstrip Patch Antenna for Mobile Communication

This paper proposes the configuration of a novel wideband patch antenna system suitable especially for indoor mobile communication applications. This configuration consists of an elevated patch antenna, which has different feed structure from classical patch antenna feed configurations that the antenna is fed by an inverted L-shape structure. The antenna structure is designed, simulated and manufactured in order to be used in mobile communication applications when used in pairs that its operation bandwidth spans 1900-2700 MHz covering Bluetooth, Wireless Local Area Networks (WLAN) and Universal Mobile Telecommunications System (UMTS) bands. Simulation and measurement results show that the antenna has wide beamwidth, low return loss and cross polarization; but, comparably higher back lobe level making the antenna more suitable for indoor applications. However, the antenna can be modified to be used in outdoor applications by increasing the ground plane size, which results in lower back lobe levels

Narrow band wide angle scanning circular frequency diverse array radar

One dimensional Linear Frequency Diverse Array (FDA) is extended to a circular two dimensional FDA array (CFDA). The CFDA operates as a pulsed FDA in the transmission (TX) mode while it operates as a pulsed phased array (PA) in the receiving (RX) mode. CFDA has a constant antenna pattern steering property in the plane of the circle while it has FDA scanning property in the orthogonal plane. This is achieved by assigning frequency offsets to the elements of the array cosinusoidally which changes with the steer angle, making the CFDA narrow band. The matched filter (MF) for pulse compression is also designed for a particular direction of interest