Browsing by Author "Secmen, M."

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A dual circularly polarized omnidirectional receiver antenna for satellite communication
(Electromagnetics Academy chew@jpier.org Suite 207777 Concord Avenue Cambridge MA 02138 USA 02138 Massachusetts, 2017) Serdar Okuyucu; Ceyhan Türkmen; Mustafa Seçmen; Secmen, M.; Okuyucu, S.; Turkmen, C.; W.C. Chew , S. He , S. He
This study describes about an omnidirectional antenna for satellite communication applications possessing dual circular polarization at almost over the full azimuth plane and wide elevation plane. The antenna does not use any septum polarizer behind it such that the circular polarization is satisfied with a simple rectangular-to-circular waveguide transition and some disks surrounding the circular waveguide with slots. The structure is fed by a rectangular waveguide and a rectangular-to-circular waveguide transition is used. Then the inclined slots in each section of the circular waveguide supported with radially outward disks are cut in the same slanted way such that +45? slots in the first section gives LHCP and -45? slots in the second section gives RHCP. The realization of the proposed antenna is carried out at Ku-band about 14 GHz. The antenna provides more than 10 dB return loss for 3 percent frequency bandwidth Besides the axial ratio for both polarizations is below 3 dB within overall azimuth plane and about 65? beamwidth of elevation plane. The gain variations in the same planes are found to be about 2.5 dBi which proves omnidirectional property of the antenna. © 2018 Elsevier B.V. All rights reserved.
A Ku-band omnidirectional circularly polarized antenna for telemetry applications in satellite communication
(Institute of Electrical and Electronics Engineers Inc., 2015) Ceyhan Türkmen; Mustafa Seçmen; Secmen, M.; Turkmen, C.
Ku-band is a frequently used frequency band especially satellite communication application. Telemetry systems collecting measurement or other kind of data are important part especially in the space segment of satellite communication. The antennas in telemetry systems are usually desired to have omnidirectional characteristics in one (usually azimuth) direction. The necessity is much more essential in satellites such that the received/transmitted signal level of satellite should not decrease significantly as the satellite rotates around its rotation axis. Besides the antennas in satellites are required to have circular polarization to get from incoming linearly polarized wave in any orientation angle without any significant power fluctuations. © 2016 Elsevier B.V. All rights reserved.
Compact and Wideband Cavity-Backed Antenna With Elliptical Coupling Slot and Elliptical Aperture for Satellite Communications Transceiver Applications
(John Wiley and Sons Inc, 2025) Yavuz Asci; Ceyhan Türkmen; Mustafa Seçmen; Asci, Y.; Secmen, M.; Turkmen, C.
A wideband full-metal cavity-backed antenna with elliptical coupling slot and elliptical aperture is proposed. The antenna consists of two elliptical structures a coupling slot and a radiating aperture which are placed on the feed waveguide side and the load side of a rectangular metal cavity resonator respectively. By using an elliptical slot/aperture the impedance bandwidth and gain of the antenna are found to be considerably improved in the same footprint and without increasing complexity compared to rectangular slot/aperture and also circular aperture. A prototype of the proposed wideband antenna is fabricated by using the additive manufacturing techniques of 3D printing with polylactic acid (PLA) material which is covered with aluminum tape to validate the design at Ku-band for satellite communication (SatCom). The measured results show that the antenna has an impedance bandwidth of 4 GHz (10.86–14.86 GHz for |S11| < −15 dB) which gives a fractional bandwidth (FBW) of 31.1%. With low cross-polarization being less than −25 dB at broadside the antenna has a peak gain of 9 dBi. The proposed antenna is also compact with a total volume of about 1.1λ03 at the center frequency. © 2025 Elsevier B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
Single Waveguide Feed Omnidirectional and Circularly Polarized Transceiver Waveguide Slot Antenna for Satellite Communication Applications
(John Wiley and Sons Inc, 2022) Ceyhan Türkmen; Esra Alkın; Mustafa Seçmen; Secmen, M.; Turkmen, C.; Alkin, E.
In this study an omnidirectional and circularly polarized transceiver antenna which can be used in simultaneous operations over transmit (TX) and receive (RX) channels for telemetry tracking and command (TTC) applications on the space segment of satellite communication is proposed. The radiation and feed parts of the antenna consist of waveguide structures for high power necessity in transmit (telemetry) section. The radiation part includes two different sections of rotationally symmetric slotted arrays on circular waveguide and radially outward metallic disks to improve omnidirectionality and circular polarization. The feed part contains a dual-band mod converter from rectangular TE10 mode to circular TM01 mode for symmetric field excitation over slots where the input of the converter is the standard rectangular waveguide. The design simulation and measurement results of the antenna are shown over a 3D printed prototype at Ku-band with center frequencies of 12 GHz and 14.25 GHz for TX and RX respectively. With thin slots in telemetry section and thick slots in telecommand section measured bandwidths for TX and RX frequencies are obtained approximately as 200 and 450 MHz respectively. While TX band with maximum 3 dB gain variation over azimuth maximum 3 dB axial ratio and minimum −3 dBi gain over 70° elevation beamwidth has relatively better performances at the expense of narrow bandwidth RX band has maximum 3.5 dB gain variation over azimuth maximum 4 dB axial ratio and minimum −6 dBi gain over 55° elevation beamwidth at the expense of wide bandwidth. © 2022 Elsevier B.V. All rights reserved.