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Papers by Gölge Ögücü Yetkin

Research paper thumbnail of Mutual coupling suppression of closely spaced microstrip antennas by ladder-shaped conducting wall

International Journal of Communication Systems, 2018

To reduce the mutual coupling between two closely microstrip antennas (MSAs), a novel ladder-shap... more To reduce the mutual coupling between two closely microstrip antennas (MSAs), a novel ladder-shaped conducting wall structure (LSCW) has been proposed and presented in this paper. This structure consists of two ladder shaped strips of copper printed on an FR-4 dielectric substrate. It is inserted between the MSAs, and also some part of LSCW surrounds a portion of each antenna. The developed compact multiple-input multiple-output system has a compact size of 50 × 25 mm 2 , and dual-band design resonates at 4.45 or 10.3-GHz frequencies depending on the dimensions of LSCW structure. It can be used in many wireless applications in C (4-8 GHz) band or X (8-12 GHz) band. The value of VSWR ≤1.5 for both resonant frequencies. Also, the diversity performance, such as the envelope correlation coefficient, the diversity gain, and the total efficiency are calculated and compared. A prototype is fabricated, and the measured mutual coupling shows that the isolation between the antenna ports has been enhanced about 50 dB at 4.45 GHz and 40 dB at 10.3 GHz.

Research paper thumbnail of Design and Fabrication of a Novel Wideband DNG Metamaterial with the Absorber Application in Microwave X-Band

Advances in Condensed Matter Physics, 2017

A novel metamaterial, which exhibits a wideband double negative behavior in X-band, is proposed, ... more A novel metamaterial, which exhibits a wideband double negative behavior in X-band, is proposed, designed, and investigated in this paper. The metamaterial is composed of modified S-shaped split-ring resonators (S-SRR). The periodic structure is designed and simulated using CST MWs. Next, the experiments are carried out, and it is shown that the simulation and the experimental results agree well and the designed structure has a wide bandwidth in X-band. An absorber application of this metamaterial is also provided, and the structure can be used as an absorber with absorption rate of over 80% for the polarization angles between 0° and 40°.

Research paper thumbnail of Mutual Coupling Reduction of E-Shaped MIMO Antenna with Matrix of C-Shaped Resonators

International Journal of Antennas and Propagation, 2018

E-shaped multiple-input-multiple-output (MIMO) microstrip antenna systems operating in WLAN and W... more E-shaped multiple-input-multiple-output (MIMO) microstrip antenna systems operating in WLAN and WiMAX bands (between 5 and 7.5 GHz) are proposed with enhanced isolation features. The systems are comprised of two antennas that are placed parallel and orthogonal to each other, respectively. According to the simulation results, the operating frequency of the MIMO antenna system is 6.3 GHz, and mutual coupling is below −18 dB in a parallel arrangement, whereas they are 6.4 GHz and −25 dB, respectively, in the orthogonal arrangement. The 2 × 3 matrix of C-shaped resonator (CSR) is proposed and placed between the antenna elements over the substrate, to reduce the mutual coupling and enhance the isolation between the antennas. More than 30 dB isolation between the array elements is achieved at the resonant frequency for both of the configurations. The essential parameters of the MIMO array such as mutual coupling, surface current distribution, envelop correlation coefficient (ECC), diversi...

Research paper thumbnail of Mutual coupling suppression of closely spaced microstrip antennas by ladder-shaped conducting wall

International Journal of Communication Systems, 2018

To reduce the mutual coupling between two closely microstrip antennas (MSAs), a novel ladder-shap... more To reduce the mutual coupling between two closely microstrip antennas (MSAs), a novel ladder-shaped conducting wall structure (LSCW) has been proposed and presented in this paper. This structure consists of two ladder shaped strips of copper printed on an FR-4 dielectric substrate. It is inserted between the MSAs, and also some part of LSCW surrounds a portion of each antenna. The developed compact multiple-input multiple-output system has a compact size of 50 × 25 mm 2 , and dual-band design resonates at 4.45 or 10.3-GHz frequencies depending on the dimensions of LSCW structure. It can be used in many wireless applications in C (4-8 GHz) band or X (8-12 GHz) band. The value of VSWR ≤1.5 for both resonant frequencies. Also, the diversity performance, such as the envelope correlation coefficient, the diversity gain, and the total efficiency are calculated and compared. A prototype is fabricated, and the measured mutual coupling shows that the isolation between the antenna ports has been enhanced about 50 dB at 4.45 GHz and 40 dB at 10.3 GHz.

Research paper thumbnail of Design and Fabrication of a Novel Wideband DNG Metamaterial with the Absorber Application in Microwave X-Band

Advances in Condensed Matter Physics, 2017

A novel metamaterial, which exhibits a wideband double negative behavior in X-band, is proposed, ... more A novel metamaterial, which exhibits a wideband double negative behavior in X-band, is proposed, designed, and investigated in this paper. The metamaterial is composed of modified S-shaped split-ring resonators (S-SRR). The periodic structure is designed and simulated using CST MWs. Next, the experiments are carried out, and it is shown that the simulation and the experimental results agree well and the designed structure has a wide bandwidth in X-band. An absorber application of this metamaterial is also provided, and the structure can be used as an absorber with absorption rate of over 80% for the polarization angles between 0° and 40°.

Research paper thumbnail of Mutual Coupling Reduction of E-Shaped MIMO Antenna with Matrix of C-Shaped Resonators

International Journal of Antennas and Propagation, 2018

E-shaped multiple-input-multiple-output (MIMO) microstrip antenna systems operating in WLAN and W... more E-shaped multiple-input-multiple-output (MIMO) microstrip antenna systems operating in WLAN and WiMAX bands (between 5 and 7.5 GHz) are proposed with enhanced isolation features. The systems are comprised of two antennas that are placed parallel and orthogonal to each other, respectively. According to the simulation results, the operating frequency of the MIMO antenna system is 6.3 GHz, and mutual coupling is below −18 dB in a parallel arrangement, whereas they are 6.4 GHz and −25 dB, respectively, in the orthogonal arrangement. The 2 × 3 matrix of C-shaped resonator (CSR) is proposed and placed between the antenna elements over the substrate, to reduce the mutual coupling and enhance the isolation between the antennas. More than 30 dB isolation between the array elements is achieved at the resonant frequency for both of the configurations. The essential parameters of the MIMO array such as mutual coupling, surface current distribution, envelop correlation coefficient (ECC), diversi...