Design of smart antenna array for interference suppression in GPS

Dabak, Ömer Can
GPS jammers add excessive noise to received low power GPS signals and have capability to weaken or completely destroy the positioning performance of GPS receivers. The most popular technique to overcome GPS jamming problem is suppression of jammers by using array signal processing techniques. In this thesis, a GPS anti-jamming system is constructed by designing an active antenna array and implementing adaptive beamforming techniques. This thesis mainly include the design of four element active circularly polarized microstrip antenna array, implementation of beamforming techniques and presentation of experimental results obtained from the constructed GPS anti-jamming system. In active antenna array design, circularly polarized operation of the array element is achieved through nearly square microstrip patch antenna structure. After verification of the design by comparing simulation and measurement results, four element planar array is designed and manufactured. Then, four channel LNA card design and production is performed in order to obtain a compact active antenna array. All electromagnetic simulation and parametric analysis of the antennas are performed in electromagnetic simulation tool CST Microwave Studio. In beamforming section, two main beamforming methods that are Capon beamforming and null steering are studied with theory and simulation results obtained from the code developed in MATLAB environment. The jammer suppression success of the constructed system is demonstrated by scenarios that include real satellites and a continuous wave jammer source.


Interference Suppression in a GPS Receiver with 4 Element Array Design and Implementation of Beamforming Algorithms
Dabak, Omer Can; Erdem, Fatih; Sonmez, Tolga; Alatan, Lale; Koç, Seyit Sencer (2016-04-14)
Global Positioning System (GPS) jammers add excessive noise to the received low power GPS signals and have capability to either weaken or completely destroy the positioning performance of GPS receivers for both civilian and military users. Researchers are actively working to develop GPS receiver systems resistant to interference sources. Our aim is to develop a system based on spatial filtering of jamming signals through the use of an active antenna array which is capable to control its radiation pattern by...
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Phase shifters are widely used for electronic beam steering for various antenna applications. This thesis presents design and comparison of 3 di erent 3-bit transmission type phase shifters, which are switch-line, Distributed MEMS Transmission Line (DMTL) and triple stub phase shifters, realized with capacitive contact Radio Frequency (RF) Micro-Electro-Mechanical Systems (MEMS) switches for Ka-Band applications. For the design of switch-line phase shifter reducing the sensitivity of the electrical performa...
Interference Supression in GPS Receivers using Spatial Filtering
Erdem, Fatih; Dabak, Omer Can; Sonmez, Tolga; Alatan, Lale; Koç, Seyit Sencer (2016-05-19)
GPS receiver operation can be interrupted by intentional/unintentional jammers even with low power levels. As the jammers become more abundant, protection of critical systems gains importance. In this work, it is aimed to suppress the GPS L1 band jammers using spatial filtering with antenna arrays. After experimental studies, it is achieved to suppress the jammers and to recover the GPS operation in real environment.
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Dual-frequency operation of antennas has become a necessity for many applications in recent wireless communication systems, such as GPS, GSM services operating at two different frequency bands, and services of PCS and IMT-2000 applications. Although there are various techniques to achieve dual-band operation from various types of microstrip antennas, there is no efficient design tool that has been incorporated with a suitable optimization algorithm. In this paper, the cavity-model based simulation tool alon...
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Citation Formats
Ö. C. Dabak, “Design of smart antenna array for interference suppression in GPS,” M.S. - Master of Science, Middle East Technical University, 2016.