Thesis Defense – Şevval Oksay (MSEE)

Şevval Oksay – M.Sc. in Electrical and Electronics Engineering

Asst. Prof. Ahmed Akgiray – Advisor

Date: 16.12.2025

Time: 16:00

Location: AB1 414

“Dual Circularly Polarized Horn Antenna and Feed Network for Full Ka-Band SATCOM”

Asst. Prof. Ahmed Akgiray, Özyeğin University

Asst. Prof. Göktürk Poyrazoğlu, Özyeğin University

Asst. Prof. Onur Hamza Karabey, Gebze Technical University

Abstract:

A compact, dual circularly polarized corrugated horn antenna and feed network system designed for small GEO satellites is presented in this thesis. The system covers the entire SATCOM Ka-band, including military frequencies from 17.7-21.2 GHz and 27.5-31 GHz. The structure comprises two main sections: the antenna section, which includes a corrugated horn antenna and a radial mode converter, and the feed network, which contains a circular-to- square waveguide transition, a six-port ortho-mode junction, waveguide low-pass filters, H-plane bends, a five-port ortho-mode junction, septum polarizers, and adapters. The transmitter frequency band is 17.7-21.2 GHz, and the receiver frequency band is 27.5-31 GHz. The minimum and maximum gains are 21.1 dBi and 23.9 dBi for the transmitter, and 23.8 dBi and 26.5 dBi for the receiver, respectively. The sidelobe level is below -31.3 dBc, and the polarization is circular. The cross-polarization discrimination exceeds 30 dB for both bands. Port-to-port isolation surpasses 20 dB, Tx-Rx isolation is greater than 63 dB, and return loss is above 30 dB. The interface uses WR51 standard waveguide at transmitter and WR34 standard waveguide at receiver. The overall structure is less than 110 x 110 x 360 mm3. The radiation patterns of both the corrugated horn antenna and the overall system are discussed as well.

Bio:

Şevval Oksay graduated from Lycée Français Saint Benoît d’Istanbul in 2016. She completed her bachelor’s degree in Electrical & Electronics Engineering at Özyeğin University, Istanbul, Turkey, in 2021. She continued with her M.Sc. studies in Electrical & Electronics Engineering with a thesis under the supervision of Asst. Prof. Ahmed Akgiray at Özyeğin University. Her research focuses on the design of SATCOM antenna systems. She also published a conference paper titled “Compact, Dual Circularly Polarized Satellite Horn Antenna and Feed Network Covering Full SATCOM Ka-Band” at the 14th IEEE-APS Conference on Antennas and Propagation for Wireless Communication, held in Palermo, Italy.