Browsing by Author "Altuntas, Mehmet"

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Citation - WoS: 3
Citation - Scopus: 5
Printed Quasi Yagi Antenna with Closely Spaced and Thick Directors for Triple ISM-Band/Wideband Applications at UHF
(IEEE, 2018) Ceyhan Turkmen; Yigit Bakirli; Mustafa Secmen; Mehmet Altuntas; Secmen, Mustafa; Turkmen, Ceyhan; Bakirli, Yigit; Altuntas, Mehmet
In this study a printed quasi Yagi antenna realized for almost whole UHF band is given. Within overall UHF band the performances of three well-known ISM frequencies of 433 866 and 915 MHz which are used in many wireless applications such as LoRa IoT M2M M-bus and RFID are desired to be kept relatively better. The proposed antenna includes a printed feed dipole with reflector and two director elements. The directors are quite thick and closely spaced to feed dipole which provides significant enhancement in the bandwidth. According to gathered results the antenna has more than 80% bandwidth for S11 < -6.5 dB between 407 and 955 MHz where return loss values are higher than 10 dB in the bands 417-493 MHz and 700-920 MHz covering three mentioned UHF ISM bands. Additionally it has more than 10 dB front-to-back ratio and 4 dBi realized gain for the frequencies lower than 500 MHz and higher than 850 MHz which again includes 433/866/915 MHz bands, while the gain values in the remaining band are relatively low as being 3.5 dBi on the average.
Citation - Scopus: 1
Wideband Omnidirectional Coplanar Waveguide-Fed Coaxial Dipole Antenna for VHF/UHF Communication Bands with Improved XPD
(Institute of Electrical and Electronics Engineers Inc., 2023) Yavuz Asci; Mustafa Seçmen; Mehmet Altuntas; Asci, Yavuz; Secmen, Mustafa; Altuntas, Mehmet
In this study a blended coplanar waveguide-fed (BCPWF) coaxial dipole antenna with improved cross-polarization discrimination (XPD) is proposed. The proposed antenna composes of a BCWF a metal cone and two stacked tubular metal cylinders. By blending CPWF the effects of the current flowing through the top surface of CPWF can be minimized. This results in low XPD and wideband omnidirectional characteristics. The effects of blend radius and thickness of CPWF on bandwidth and XPD are investigated. Besides ferrite material is utilized in the connector side to eliminate leakage currents at low frequencies. The effects of the ferrite material on the radiation pattern and VSWR are demonstrated for long cable applications. The proposed antenna operates 99-1202 MHz (VSWR <2.15, 169.8%) and has 0.48λ × 0.04 λ transverse dimensions. The peak gain of the proposed antenna is 6 dBi. The azimuth (H-plane) gain ranges from -1 dBi to 1.5 dBi for Airband (108-137 MHz) and Mode-S/ADB(800-1100 MHz) communication bands. Due to its wideband omnidirectional easy manufacturing and low-cost properties the proposed antenna can be used in high-tower vehicle shipboard and air traffic control platforms in the VHF/UHF band. © 2024 Elsevier B.V. All rights reserved.