Greetings Colleagues. A topic of discussion and controversies commonly among radio amateurs, which has now been eradicated thanks to the knowledge of the theory, is that of the physical lengths to be used in the coaxial cables of our antenna systems. There are several opinions and arguments supported on theoretical bases, there is enough technical information on the subject, with a high level of engineering and where the non-dependence of the length to be used in coaxial cables is demonstrated. However when we install radio stations we get with seemingly out of logic situations ( Most noticeable in short wavelength HF ), equally indicated in theory and easy to analyze, not taken into account by many experts, but that make us dependent of the length in the line, we do not notice it and in many cases we do not recognize it. Because not all readers are knowledgeable about the topic, this article explains in a simple way what typically not considered by many experts, as well as the advantages of using coaxial lines of resonant lengths, only for SWR lower than 2.0, characteristic impedances of 50 ohms and typical propagation speeds on the market. In most studies and articles on physical lengths of transmission lines they use confusing terminology for beginners, generalizing ideal systems and impedance balances only for a specific frequency, without taking into account the displacement of the original resonance frequency of the antenna and its behavior in the spectrum, these being the main reasons and themes of this article. Opportunities will use a familiar language comprehensible, with its explanations due to the beginning or end of the article. Hoping to be useful and serve as the initial tool for optimizing our radio stations. Link to download the PDF file: https://files.acrobat.com/a/preview/eb9e1f6d-73ee-4322-aebd-c1dac4687207 If you would like to provide some information to add to this article, please contact us via email: firstname.lastname@example.org , email@example.com , firstname.lastname@example.org This and other articles I have written, are free to use and the latest versions are always available in www.qrz.com/db/YY5RM or entering www.qrz.com ( YY5RM in the search ). QRV.