Sistema de medición del patrón de radiación de antenas en el rango de 1 MHz a 4 GHz. Mejora de rango dinámico y mando remoto

Abstract

At the Faculty of Engineering, a didactic system was designed to obtain radiation patterns of antennas in a frequency range of 1 to 6 GHz, which uses a radio signal power RMS detector. In the present work, some improvements are presented in the system. A logarithmic detector and a radio signal power RMS detector were used. With the RMS detector, a dynamic range of 61 dB was obtained and with the logarithmic detector a dynamic range of 78 dB. To increase the dynamic range, a low noise amplifier (LNA) with a gain of +20 dB has been implemented. Taking into account the losses of the elements, a sensitivity of -69 dBm was obtained, with the possibility of using two low noise amplifiers (LNA) to extend the sensitivity to -85 dBm. The system has a support for the transmitting antenna and another for the receiving antenna. The receiving antenna and its support rotate around an axis and have a wireless control system. The upper part of the support communicates with the lower part by means of Bluetooth communication for the transfer of data, this solves the problem and the difficulties with the wiring that the initial system had. Due to the fact that an anechoic chamber is not available, RF filters were used in the test frequency to improve the definition of the radiation pattern by attenuating strange signals to the test ones. To control and synchronize the system, a program was designed in the Python language. The program implements a graphical interface that controls the entire measurement process. The program is connected to the reception system by serial communication and thus controls the rotation of the axis of the reception tower and the data transfer. Measurements are made at several test frequencies and different types of antennas with their corresponding RF filters. The results were contrasted with theoretical results. The resulting graphs verify a good approximation of the system designed with the theoretical predictions.