Diseño y fabricación de filtros paso bajo tubulares

The objective of this project was to design and manufacture a tubular low pass filter. The filter was designed with the technique of impedance steps and it meets the necessary specifications and frequency mask. Besides, I wanted to carry out a process of design and manufacture filters as automated as possible in order to follow the same process more quickly in future designs. The reason to develop this project has been the need for filters in the radiofrequency laboratory. These filters can be purchased nowadays but the problems of buying them are their high cost and the long delivery time. Therefore, in this project I want to find out whether we can manufacture filters with similar characteristics to the filters that are on the market, with a lower cost and avoiding the long delivery time. The type of filter that I have designed is explained at the beginning of this document. Moreover, the characteristics that I wanted to achieve are described in detail. Then, the calculations that were carried out to obtain the ideal filter dimensions and the automation of these operations using Matlab are presented. Once the ideal filter design was obtained, it was simulated with the circuit simulatos ADS. In order to obtain simulations as real as possible, the filter was implemented and simulated with a 3D software: HFSS. Some discrepancies were observed, so that the previously calculated dimensions were modified to obtain the filter performance required. To finish the document, the manufacturing process is explained, the measurements of the resulting prototype are shown and the conclusions and future lines are exposed.