The main problem with sending interstellar messages is that with the distance traveled, their power gradually decreases due to gradual scattering ( diffraction). Imagine that you threw a stone into the quiet surface of a lake: from the source stone, circles started to go in all directions, but the further they diverge, the less noticeable they become. The same thing happens with radio waves: if you calculate approximately, then twice the distance from the communication source will reduce the power of radio waves by four times. As you can see, detecting such radio waves at a distance of several hundred light-years from Earth will be a difficult task for space civilizations.
And here is the whole question: how can we send an interstellar message in all directions ( since we want to make ourselves known to everyone ) so that we can be heard?
Note: please describe the technical features in as much detail as possible and give the appropriate calculations, as if you really want to make yourself known as loudly and further as possible.
Also, please do not offer answers related to really huge energy costs or the use of astroengineering, such as the construction of the Dyson sphere.
The signal transmitted by our civilization should be focused on civilizations of technological development similar to us ( starting from the mid-20th century ), but if you know how to make the signal available to less developed civilizations, for example, at the end of the 19th century, I will be happy to hear from you.