Here’s an interesting article about the transmission in 1999 of a carefully assembled message to whomever might reside at nine sun-like stars 50-70 light years from the solar system: How a Couple of Guys Built the Most Ambitious Alien Outreach Project Ever: You might think it takes vast governmental resources to launch an extraterrestrial communication effort. Nope – Smithsonian Magazine.
Some technical details about the project and the construction of the message: