RF front end and antenna design for LTE mobile systems

Mobile device usage is growing day by day and wireless communication technologies are developing even at greater pace. Despite the increase in the expectations of end users from mobile devices, the size of the devices is getting smaller. In particular, the demand for much higher data rates and the increase in the number of end-users pushes the development of wireless communication systems even further. RF front-end and antenna design will be considered within the scope of thesis study. The new concept will also be proposed to increase the receiver performance of mobile devices. With the evolution of cellular communication systems, there has been significant progress in data rates. However, every new telecomunication generation provides great advantages compared to the previous one, but it cannot replace the previous generation due to reasons such as infrastructure installation and coverage. In this case, mobile devices need to support the latest generation communication systems as well as older generations to meet the needs of the end user. In addition, the spectrum assignment determined by the states according to the region where the mobile device will be used varies. When designing the RF front-end and antenna of mobile devices, the cellular technology and RF bands to be supported should be determined by considering these two conditions. For the last generation 4.5G support, the operators' promotion for Carrier Aggregation (CA) combinations should be investigated and the RF front-end and antenna design should be planned accordingly. CA, which is widely used by 4.5G, allows you to communicate with more than one RF band simultaneously. This increases the data rate by the number of RF bands used in theory. One of the objectives of the thesis study is to complete the RF front-end and antenna designs of mobile devices that support CA and to highlight the specific design criterias. Another aim of the study is to increase the RF receiver performance of the device thanks to the proposed new concept. With the decrease in the size of mobile devices, RF performances have been greatly affected by the usage scenarios. In particular, when the end user uses the mobile device with his/her head and/or hand, the radiation performance of the main and/or diversity antenna communicating with the cellular communication systems is severely reduced. In order to prevent this decrease, GPS or WiFi antenna is planned to be used as a diversity antenna in the scenario where the radiation performance of the diversity antenna is low. While this operation was carried out, GPS and WiFi operations should not lose their performance in terms of radiation. With the architectural and theoretical calculations, 1-2dB is sacrificed from GPS and WiFi performance and it is anticipated that the cellular communication performance of the device will be increased. With the implementation of the proposed new concept, the measurements taken in parallel with the theoretical calculations showed an improvement of up to 6dB in the cellular performance of the device. The accuracy and applicability of the concept has been proven in this way.