Thesis Defense – Rümeysa Tuba Seven İyison (MSEE)

Rümeysa Tuba Seven İyison – M.Sc. in Electrical and Electronics Engineering

Asst. Prof. Göktürk Poyrazoğlu – Advisor

Date: 29.12.2025

Time: 15:00

Location: AB1 413

“IMPROVING OVER-THE-AIR ANTENNA PERFORMANCE TO STABILIZE LTE/5G CELLULAR COMMUNICATION IN

ALTERNATING CURRENT ELECTRIC VEHICLE CHARGERS”

Asst. Prof. Göktürk Poyrazoğlu, Özyeğin University

Asst. Prof. Umut Başaran, Özyeğin University

Asst. Prof. Çağatay Aydın, Ege University

Abstract:

This thesis aims to ensure robust cellular connectivity for alternating current electric vehicle (AC EV) chargers by implementing reliable communication protocols and optimizing antenna performance. Key performance metrics, such as Total Radiated Power (TRP) and Total Isotropic Sensitivity (TIS), are used to assess connectivity between the cellular module, antennas, and the base station. Root-cause analyses identify the factors degrading antenna performance, while theoretical evaluations support the proposed design improvements. The results offer a framework to enhance connectivity, ensuring remote control of AC EV chargers as mandated by the Open Charge Point Protocol (OCPP). The proposed methodology is validated on two AC EV charger platforms. For the EVC01 platform, low-band Long Term Evolution (LTE) degradation is shown to result from near-field interaction between the antenna and Printed Circuit Board (PCB), together with conducted interference components. Restructuring the PCB layout and applying a common-mode filter improves LTE Band 8 TIS by approximately 6 dBm. For the EVC08 platform, the dominant issue is near-field coupling induced by the internal panel structure, and suppressing resonance through a dual-point grounding approach improves LTE Band 8 TRP by approximately 6 dBm. Furthermore, for 5G New Radio (NR) operation on the EVC08 platform, optimized antenna placement and proper port–band mapping yield approximately 17 dBm improvement in TIS for the n5, n20, and n28 bands, ensuring stable connectivity across all tested channels. This thesis establishes a physically consistent and experimentally validated framework to improve LTE/5G NR cellular communication performance in AC EV chargers.

Bio:

Tuba Seven received her B.Sc. degree in Electrical and Electronics Engineering from Dokuz Eylül University, Izmir, Turkey. She is currently pursuing her M.Sc. studies in Electrical and Electronics Engineering at Özyeğin University and works as a System Design Engineer at Vestel Electronics. Her research focuses on LTE/5G antenna performance, electromagnetic compatibility (EMC), and the over-the-air characterization of cellular communication systems in AC electric vehicle chargers. She is the author of the conference paper titled “Improvement of Over-the-Air Antenna Performance Tests for Electric Vehicle Alternating Current Chargers,” presented at the 49th International Spring Seminar on Electronics Technology (ISSE 2025) in Budapest, Hungary. She also authored the paper titled “Alternatif Akım Elektrikli Şarj Cihazlarında LTE/5G Hücresel Haberleşmenin Stabilizasyonu için Anten Performans Testlerinin İyileştirilmesi,” presented at the URSI-TR 2025 XII Scientific Congress and National General Assembly in Izmir, Turkey.