Master Thesis Master's Programme in Electronics Design, 60 credits Design of Cellular and GNSS Antenna for IoT Edge Device in collaboration with HMS Industrial Networks AB Electronics Engineering,15 credits Halmstad 2019-04-10 Ioannis Broumas HALMSTAD UNIVERSITY 60 Credits Author Ioannis Broumas Supervisor Johan Malm Examiner Pererik Andreasson School of Information Technology Halmstad University PO Box 823, SE-301 18 HALMSTAD Sweden 2 Abstract Antennas are one of the most sensitive elements in any wireless communication equipment. Designing small-profile, multiband and wideband internal antennas with a simple structure has become a necessary challenge. In this thesis, two planar antennas are designed, simulated and implemented on an effort to cover the LTE-M1 and NB-IoT radio frequencies. The cellular antenna is designed to receive and transmit data over the eight-band LTE700/GSM/UMTS, and the GNSS antenna is designed to receive signal from the global positioning system and global navigation systems, GPS (USA) and GLONASS. The antennas are suitable for direct print on the system circuit board of a device. Related theory and research work are discussed and referenced, providing a strong configuration for future use. Recommendations and suggestions on future work are also discussed. The proposed antenna system is more than promising and with further adjustments and refinement can lead to a fully working solution. 3 Στον αδελφό μου Μάκη 4 Contents 1. Introduction ................................................................................................................................................ 10 1.1 Project Overview ....................................................................................................................................... 11 1.2 Specifications ............................................................................................................................................ 13 1.3 Design Problem ......................................................................................................................................... 13 1.4 Methodology............................................................................................................................................. 14 2. Antenna Theory .......................................................................................................................................... 16 2.1 Antenna Electrical Size .............................................................................................................................. 16 2.1.1 Fundamental Limits of Electrically Small Antennas ................................................................... 17 2.2 Bandwidth ................................................................................................................................................. 17 2.2.1 Bandwidth Limitations ............................................................................................................... 17 2.3 Impedance Matching ................................................................................................................................ 18 2.4 Microstrip Antennas ................................................................................................................................. 18 2.5 Monopole Antennas ................................................................................................................................. 19 2.5.1 Ground Plane as an Electrical Mirror ......................................................................................... 20 2.5.2 Properties of Small Monopoles .................................................................................................. 20 2.5.3 Effect of Nearby Metal on Monopole Type Antennas ............................................................... 21 2.5.4 Effect of Reduced Ground Size on Monopole Antennas ........................................................... 21 2.6 Miniaturization Techniques ...................................................................................................................... 21 2.7 Multi-band/Broadband Antenna Design Techniques ............................................................................... 22 2.8 Environmental Effects in ESAs .................................................................................................................. 24 2.9 Trade‐Offs in Antenna Design ................................................................................................................... 24 3. Cellular Antenna ......................................................................................................................................... 25 3.1 Basic Design Steps ..................................................................................................................................... 25 3.2 Operating Mechanism .............................................................................................................................. 26 3.3 Antenna Design ......................................................................................................................................... 27 3.3.1 Results from ADS Momentum ................................................................................................... 27 3.3.2 Results from FEKO ...................................................................................................................... 28 3.4 Conclusion ................................................................................................................................................. 29 4. GNSS Antenna............................................................................................................................................. 30 4.1 GNSS Radio Wave Propagation ................................................................................................................. 30 4.2 Omnidirectional Antennas for Mobile Satellite Communications ............................................................ 30 4.3 CP Antenna Design .................................................................................................................................... 30 5 4.4 GNSS Antenna Constraints ........................................................................................................................ 31 4.5 Multipath Environment, Human Body and Platform Effects .................................................................... 31 4.6 Size and Shape of the Antennas ............................................................................................................... 31 4.7 Basic Design Steps ..................................................................................................................................... 31 4.8 Antenna Design ......................................................................................................................................... 32 4.8.1 Results from ADS Momentum ................................................................................................... 33 4.8.2 Results from FEKO ...................................................................................................................... 35 4.9 Conclusion ................................................................................................................................................. 37 5. Full Antenna System ................................................................................................................................... 37 5.1 Simulations Results ................................................................................................................................... 37 5.1.1 Results from ADS Momentum ................................................................................................... 37 5.1.2 Results from FEKO ...................................................................................................................... 39 5.1.3 PCB mounted in bolt and on cabinet ......................................................................................... 41 5.2 Fabrication ................................................................................................................................................ 41 5.3 Discussion ................................................................................................................................................. 43 5.4 Conclusion ................................................................................................................................................. 45 5.5 Future Work .............................................................................................................................................. 45 Disclaimer ........................................................................................................................................................... 46 References .......................................................................................................................................................... 47 6 List of figures Fig.1 - IoT Bolt Fig.20 - GNSS Antenna altered feeding Fig.2 - IoT Bolt mounted on cabinet Fig.21 - GNSS Antenna S11 results from ADS Fig.3 - Bolt Dimensions Fig.22 - GNSS Antenna S11 SC results from ADS Fig.4 - PCB representation Fig.23 - GNSS Antenna in FEKO Fig.5 - Antenna general representation Fig.24 - GNSS Antenna S11 results from FEKO Fig.6 - Antenna within a sphere Fig.25