Bahattin Turetken

An Improved Design of Planar Elliptical Dipole Antenna for UWB Applications

In this letter, an enhanced planar elliptical dipole antenna design for ultrawideband (UWB) communication and impulse radar systems is presented. The printed-circuit-elliptical (PCE) antenna has been investigated to be an effective radiator for UWB applications. To enhance gain and return loss bandwidth of the antenna, elliptical slots are used on the dipole arms. The gain performance of the antenna has been increased by means of elliptical slots in the frequency range from 2.7 to 11 GHz. The standing wave ratio is less than 2 (SWR < 2) along 94.4% of operation bandwidth from 1.1 to 11 GHz. The radiation pattern in E- and H-plane for certain frequencies, the return loss, and the gain performance are presented with the experimental and simulation results. Moreover, the time domain analysis of the antenna is presented. The antenna introduces low-level ringing and pulse distortion. Consequently, the antenna is very useful for impulse and UWB communication systems.

Dielectric-Loaded Compact WLAN/WCDMA Antenna With Shorted Loop and Monopole Elements

A compact, planar, dielectric-loaded, and multiple-band antenna for 2.45/5-GHz WLAN and 2.1-GHz wideband code-division multiple access (WCDMA) applications is presented in this letter. The antenna has a planar loop element with a shorting pin and a planar monopole element that are printed on the same substrate and driven by a microstrip line. The loop and monopole elements are covered by a thin FR4 layer on top to achieve good impedance matching at both bands. Analysis of the antenna has been realized using extensive 3-D full-wave electromagnetic simulations. Antenna measurements have also been presented, and it is shown that measurements and simulations are in good agreement.

An experimental microwave imaging system for breast tumor detection on layered phantom model

In this paper, the microwave imaging system currently being developed and realized at the Scientific and Technological Research Council-BILGEM, is introduced. A stacked patch antenna has been designed, fabricated and tested in operation in the experimental setup consisting of a spectrum analyzer (with vector network analysis option) and a planarly layered breast phantom model with tumor. Images are successfully obtained by using scattering electromagnetic waves from the tumor (S11). In the future study, ultrawide-band (UWB) confocal microwave radar-based imaging system with right-handed circularly polarized (RHCP) and left-handed circularly polarized (LHCP) antennas located as an array on a section of a hemisphere, as well as improved and fast imaging algorithms, will be designed and developed in order to minimize mutual coupling between antenna elements, reflections from the skin and mechanical parts of the antenna system for getting better resolution results than similar recent developed microwave imaging systems.

Reconfigurable fractal tree antenna for multiband applications

This paper evaluates reconfigurable specification of the fractal tree antenna. Fractal tree antenna fed by a 50 ohms round coax from its middle. Making PIN-diodes on or off state, the characteristic of antenna changes and it results changes in the operation frequency and radiation pattern. The proposed antenna demonstrates reconfigurable frequency range from 1.51 GHz up to 8.6 GHz. Analysis of the antenna has been done by means of commercial software CST Microwave Studio to discuss the impression of different dimensional parameters by controlling the PIN diode switches on radiation pattern, directivity and operational frequency.

Radiation of sound waves from a rigid stepped cylindrical waveguide

The radiation of plane harmonic sound waves from a rigid stepped cylindrical waveguide is treated by using the mode-matching method in conjunction with theWiener-Hopf technique. The solution is exact, but formal, since infinite series of unknowns and some branch-cut integrals with unknown integrands are involved. Approximation procedures based on rigorous asymptotics are used and the approximate solution to the Wiener-Hopf equations is derived in terms of infinite series of unknowns, which are determined from infinite systems of linear algebraic equations. Numerical solutions of these systems are obtained for various values of the parameters of the problem and their effects on the directivity of the stepped waveguide is presented.

Antenna arrangement considerations for microwave hyperthermia applications

This paper presents the adequateness of a rectangular spiral shaped patch antenna and a Vivaldi antenna having narrow beam width to use for antenna arrangements in microwave hyperthermia applications. The results obtained from simplified leg model show the adequateness of the small size spiral antenna due to its capability to operate at multi frequencies and narrow beam width. In addition its small lateral size is promising to use it in multi antenna configuration system for microwave hyperthermia application for cancer treatment.

Design of compact microstrip antennas embedded in water bolus for hyperthermia applications

This paper presents the design of a circularly shaped spiral microstrip antenna and a conventional patch antenna both are embedded inside a distilled water bolus. The adequateness of the antennas is investigated for hyperthermia applications. The novelty of the spiral antenna is, it has a narrower radiation pattern and resonates at multiple frequencies to have a better control over the penetration depth and focusing considerations.

Design and realization of printed LPDA at UHF band

In this paper design and realization of an PLPDA antenna is presented. This contribution describes how to produce a PLPDA for UHF frequencies and experimental results of the effects of design parameters on the radiation pattem of the antenna. For maximizing performance of PLPDA antenna, attention was focused on such important parameters as beamwidth, gain and impedance. The eficiency of the antenna has been obtained by measuring the SI, parameters. Furthermore, the beam panem measurements were done at 5-degree intervals in an anechoic chamber. Also antenna factor determination inside GTEM Cell is investigated

Diffraction from a Grating on a Chiral Medium: Application of Analytical Regularization Method

Theoretical results on the electromagnetic wave difiraction from a periodic strip grating placed on a chiral medium are obtained. Analytical Regularization Method based on the solution to the vector Riemann-Hilbert boundary value problem was used to get robust numerical results in the resonant domain, where direct solution methods typically fail. It was shown that in the case of normal incidence of linearly polarized wave the cross-polarized fleld appears in the re∞ected fleld. For elliptically polarized incident wave the difiraction character essentially depends on the polarization direction of the incident wave. These difiraction peculiarities are more pronounced in the resonant domain. In∞uence of the dichroism caused by chiral medium losses is thoroughly studied. The combination of a chiral medium and a grating can be efiectively used for a frequency and polarization selection and for a mode conversion.

Design and realization of ultra wide-band implant antenna for biotelemetry systems

The aim of this study is to design of a small size implantable antenna involving Industrial, Scientific and Medical (ISM) (2.4 GHz-2.48 GHz) band. The goal of designing antenna is to obtain physiological information pertaining to person. Simulation measurements of antenna were obtained in body ambient by making the design of antenna with CST Studio Suite programme. Then, in vitro measurements were performed on antenna by making an artificial material, which shows electrical features of human skin tissue, to verify measurement results. Obtained measurement results and simulative results are in accordance.