Merih Palandoken

Negative refractive index material-inspired 90-deg electrically tilted ultra wideband resonator

Abstract. A negative refractive index material loaded patch antenna is proposed for ultra wideband applications. The wideband operation has been achieved by creating a defected ground plane with a CNC shaped split ring resonator. The defected ground plane CNC resonator also exhibits a 90-deg electrical tilt. Two additional slots are engineered in the patch antenna for further bandwidth enhancement. A −10  dB bandwidth with an order of 57.89% has been achieved with a peak gain of 5.37 dBi at a 5.5 GHz resonant frequency. Measured results demonstrate good agreement with simulated results.

Novel stacked μ -negative material-loaded antenna for satellite applications

An engineered novel tunable dual-band metamaterial antenna based on stacked split ring resonator (SRR) array is presented. The μ-negative SRR array present at two sublayers of stacked microstrip patch antenna substrate adds tuning capability to the antenna with marginal trade-off between antenna gain and cross-polarization. If the size of resonator element is considerably smaller than resonance wavelength, ideally lesser than λ/10, the resonator would support the resonating mode of antenna. Compact SRR array embedded in radiator facilitate the antenna tuning to intended allocated spectrum of L5- and S-band frequencies without modifying external dimensions of patch antenna, which in turn helps the satellite payload design. The variations in SRR array dimensions and inter-element spacing are subsequently utilized to maintain the antenna gain and voltage-standing wave ratio. The proposed design of inset fed antenna, matched at 50 Ω, was validated by experimental results and it is suitable for global positioning satellite applications.

DUAL-BAND POLARIZATION-INSENSITIVE METAMATERIAL INSPIRED MICROWAVE ABSORBER FOR LTE-BAND APPLICATIONS

In this paper, the design, simulation and measurement of a dual-band polarizationinsensitive metamaterial inspired microwave absorber are presented. The unit cell is composed of two concentric closed ring resonator (CRR) structures forming octagonal rings which are carved on an FR-4 dielectric substrate to give maximum absorption at dual frequencies of 2.09 GHz and 2.54 GHz. At these frequencies, the minimum reflection coefficients of −29.15 dB and −18.76 dB are achieved with absorption rates of 99.88% and 98.67% and narrow 10 dB bandwidths of 2.62% and 2.76%, respectively. Microwave absorption property of the proposed absorber structure is simulated by setting the perfect electric boundary conditions in four planes whose surface normal vectors are directed perpendicular to the wave propagation direction. These numerical computation settings replicate the rectangular waveguide to be used in the experimental measurements for the comparison between the simulated and experimental results. It is experimentally verified by the waveguide measurement method that the absorption rates about 99% are achieved for dual bands with polarization insensitivity thereby meeting the absorption requirements of LTE-band frequencies for a real time microwave absorber based energy harvesting systems.

Low cost dual band monopole antenna design and analysis for 802.11 b/g/n/ac standards

In this study, low-cost dual-band monopole antenna design and analysis are performed for wireless communication systems nowadays widely used. In the first section, numerical and experimental studies have been done for three antenna geometries selected from the literature. In the second section, radiation parameters and input impedances of the antennas are investigated along with numerical calculations and experimental results for three antennas, each of which are designed in combination with artificial magnetic conductor (AMC) structures. The purpose of this study is to present methodology compatible with developing technological standards in low cost in order to design compact, different types of microstrip antenna geometries which can operate in WLAN 802.11 ac/b/g/n wireless communication standards.

Compact multiband MIMO antenna designs and analysis for 2.4/5.2/5.8 GHz WLAN MIMO systems

In this study, high gain, low noise MIMO antenna system have been analyzed and designed in wireless ISM band communication system. An isolation technique for two small-size WLAN MIMO laptop computer antennas covering the 2.4/5.2/5.8 GHz bands is presented. The aim of this project is to present several types of compact MIMO antennas for ISM 2.4 and 5.8 GHz band, and then to compare and interpret the results. Besides, some information was provided as to the ISM band and transceiver systems. Also, the correlation coefficient and diversity gain, which represents a significant value for MIMO antennas, has been analysed in this paper. The different geometries of microstrip antennas such as slot-loaded microstrip patch arrays, dual-band and loaded dipole rectangular microstrip patch are simulated with CST Software, using FDTD.