Evaluation of a low cost procedure to perform a transmission line matching for lab courses

This paper focusess on the investigation of a planar structure using a low cost and hand made kit proposed in literature. The focus of the study in a educational kit to investigate transmission lines, basic circuit elements that are very important in the field of telecommunications. Since the focus is educational, we evaluate the kits using the following guidelines: If the phenom is well represented in the circuit, if it is possible to understand and evaluate the event. The event here studied is the matching of a mismatched transmission line. A mismatched transmission line losses power due to reflections and therefore, is not so efficient as it could be. There are some techniques used to match transmission lines, such as one quarter wave length transformers and stub matching. In this paper we will use the stub technique due to easiness of fabrication and the possibility to use the already assembled kits. To evaluate the performance of the kits, a network analyzer were used and the return loss was measured, also called S11 parameter. The results show that at the desired frequency, the s11 parameter is really lower in the matched line than in the mismatched line, resulting in a fall of more than 15 dB, what is representative for the phenom. With this results, the study of the use of the kits for other planar structures is encouraged.