Design and holistic evaluation of dual-band circularly polarized smartphone antenna for direct-to-device non-terrestrial networks
(2026) EITM02 20261Department of Electrical and Information Technology
- Abstract
- Direct-to-Device (D2D) communication in Non-Terrestrial Networks (NTNs) enables smartphones to connect directly to satellites, extending wireless coverage beyond terrestrial networks. This thesis presents the design of a smartphone antenna optimized for NTN operation, followed by a link budget analysis and Electromagnetic Field (EMF) exposure assessment.
The proposed solution is a dual-band circularly polarized antenna operating in the S-band NTN frequency ranges. The antenna is specifically optimized to provide radiation towards the upper hemisphere, while satisfying the size constraints of a smartphone. In addition, a linearly polarized C-band antenna is obtained as an extension of the S-band structure, enabling additional... (More) - Direct-to-Device (D2D) communication in Non-Terrestrial Networks (NTNs) enables smartphones to connect directly to satellites, extending wireless coverage beyond terrestrial networks. This thesis presents the design of a smartphone antenna optimized for NTN operation, followed by a link budget analysis and Electromagnetic Field (EMF) exposure assessment.
The proposed solution is a dual-band circularly polarized antenna operating in the S-band NTN frequency ranges. The antenna is specifically optimized to provide radiation towards the upper hemisphere, while satisfying the size constraints of a smartphone. In addition, a linearly polarized C-band antenna is obtained as an extension of the S-band structure, enabling additional functionality. The antenna performance is evaluated in terms of impedance matching, radiation characteristics and efficiency, and its impact on system performance is evaluated by a link budget analysis based on a Low Earth Orbit (LEO) satellite scenario. The results demonstrate that the optimized S-band antenna achieves data rates ranging from several kbps to several Mbps, depending on transmit power and elevation angle, demonstrating its suitability to enable NTN communication with significant data rates. In the C-band, the system can provide additional connectivity, supporting low data rate services, due to higher propagation losses and reduced antenna gain in the skywards direction. Electromagnetic exposure is assessed through Specific Absorption Rate (SAR) simulations. The results show that SAR levels remain within international limits when using certain duty cycle transmission period, needed at certain phone positions relative to the body and higher transmit power levels.
The findings provide insights into the trade-offs between antenna design, link performance, and user exposure in the context of smartphone-based NTN communication. (Less) - Popular Abstract
- Today’s mobile networks allow people to stay connected in many places around the globe, but some regions still lack reliable communication. This can be particularly problematic in emergency situations, where a connection may be critical to safety.
A promising solution to this challenge is to use satellites that provide communication services directly to smartphones. Instead of relying on ground base stations, a phone could connect directly to a satellite orbiting the Earth, enabling coverage in any location on the planet. However, in order to make this possible, improved antennas in the smartphones are required, as the current systems are not designed to communicate over such large distances between the user and a satellite.
In this... (More) - Today’s mobile networks allow people to stay connected in many places around the globe, but some regions still lack reliable communication. This can be particularly problematic in emergency situations, where a connection may be critical to safety.
A promising solution to this challenge is to use satellites that provide communication services directly to smartphones. Instead of relying on ground base stations, a phone could connect directly to a satellite orbiting the Earth, enabling coverage in any location on the planet. However, in order to make this possible, improved antennas in the smartphones are required, as the current systems are not designed to communicate over such large distances between the user and a satellite.
In this thesis, a specific type of antenna was designed to enable connectivity between the smartphone and the satellite. The antenna is designed to fit within the limited space of a modern smartphone, while directing the signal towards the sky, where the satellites are located. In addition, the amount of information that can be transmitted over this link was analyzed, and electromagnetic field exposure is evaluated as it is needed to ensure compliance with limit values.
The results show that it is possible for a smartphone to establish a connection with a satellite, particularly at certain frequencies that are specifically reserved for this use. However, the large distance between the phone and the satellite leads to a very weak signal, making a robust antenna design essential.
Overall, this work demonstrates that direct satellite communication with modern smartphones is technically feasible, but it requires a careful balance between performance and reliability. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/student-papers/record/9244249
- author
- Montoro García, Pablo LU
- supervisor
- organization
- course
- EITM02 20261
- year
- 2026
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Non-Terrestrial Networks (NTN), Direct-to-Device (D2D), Smartphone Antenna, Circular Polarization, Dual-Band Antenna, Satellite Communications, Link Budget Analysis, Specific Absorption Rate (SAR), Electromagnetic Field Exposure (EMF), Antenna Design, S-Band, C-Band, Radiation Pattern, Antenna Efficiency, Impedance Matching, Mobile Terminals, Satellite-to-Device Communication, Wireless Communications, 3GPP NTN, User Equipment (UE)
- report number
- LU/LTH-EIT 2026-1182
- language
- English
- id
- 9244249
- date added to LUP
- 2026-06-29 11:39:15
- date last changed
- 2026-06-29 11:39:15
@misc{9244249,
abstract = {{Direct-to-Device (D2D) communication in Non-Terrestrial Networks (NTNs) enables smartphones to connect directly to satellites, extending wireless coverage beyond terrestrial networks. This thesis presents the design of a smartphone antenna optimized for NTN operation, followed by a link budget analysis and Electromagnetic Field (EMF) exposure assessment.
The proposed solution is a dual-band circularly polarized antenna operating in the S-band NTN frequency ranges. The antenna is specifically optimized to provide radiation towards the upper hemisphere, while satisfying the size constraints of a smartphone. In addition, a linearly polarized C-band antenna is obtained as an extension of the S-band structure, enabling additional functionality. The antenna performance is evaluated in terms of impedance matching, radiation characteristics and efficiency, and its impact on system performance is evaluated by a link budget analysis based on a Low Earth Orbit (LEO) satellite scenario. The results demonstrate that the optimized S-band antenna achieves data rates ranging from several kbps to several Mbps, depending on transmit power and elevation angle, demonstrating its suitability to enable NTN communication with significant data rates. In the C-band, the system can provide additional connectivity, supporting low data rate services, due to higher propagation losses and reduced antenna gain in the skywards direction. Electromagnetic exposure is assessed through Specific Absorption Rate (SAR) simulations. The results show that SAR levels remain within international limits when using certain duty cycle transmission period, needed at certain phone positions relative to the body and higher transmit power levels.
The findings provide insights into the trade-offs between antenna design, link performance, and user exposure in the context of smartphone-based NTN communication.}},
author = {{Montoro García, Pablo}},
language = {{eng}},
note = {{Student Paper}},
title = {{Design and holistic evaluation of dual-band circularly polarized smartphone antenna for direct-to-device non-terrestrial networks}},
year = {{2026}},
}