The Starship Voyager was designed by Rick Sternbach over the course of almost a year, starting in September 1993, when The Next Generation entered its final season.
Forgotten Trek has detailed Sternbach’s design process here. But there were other designers who contributed to the new ship.
Doug Drexler, who was working on Star Trek: Deep Space Nine at the time, submitted several ideas. So did Jim Martin. Their concepts give us a glimpse at what might have been.
Drexler’s were low-resolution computer-generated images, one of which showed a long, dart-like primary hull that matched Sternbach’s thinking.
Drexler would use another design — the one with the ring-shaped warp drive — as a starting point for the Vulcan Suurok-class cruiser on Star Trek: Enterprise almost a decade later.
Most of Martin’s designs for Voyager were reminiscent of the Defiant, which he had designed for Deep Space Nine. One looked like an updated version of the Oberth class. Another appears to have influenced the design of Chakotay’s Maquis raider, which appeared in the Voyager pilot, “Caretaker”.