This novel made a tremendous impact on me as a kid in the late '50s or early '60s, and I would like to read it again. I’ve looked through lists of hundreds of titles from the era without finding it. What I remember: A galactic empire exists. Travel between already developed worlds is so fast, using sender and receiver transporters, that that the gases around the transported do not escape.
A transport technician discovers the scam where the only destination for exiles is a metal-poor prison world (Eden?) no matter what world they choose. He modifies a spaceship so that it is both sender and receiver (with an old fashioned loop antenna on front, which may have been on the cover), and can travel anywhere he likes. He fights the galactic government, and at one point his ship accidentally self-transports for hours, taking him to a weird and distant galaxy.