Mission statement: Similar organizations

The Antarian Rangers are not the only organization to help the Jedi, in the words of Allston: “Freedom’s sons were one such order, and the Rangers were another”. According to Wookieepedia, the Antarian Rangers are “similar in name and function to the Aquillian Rangers” (this apparently interprets The Making of Star Wars: The Definitive Story Behind the Original Film) and “fill a similar role to the Freedom Warriors”:

“The Freedom Warriors were highly trained troops supporting the Jedi Order in resource-heavy operations. Although the unit’s ranks were only open to those who could not feel the Force as Jedi do, the Freedom Warriors were able to effectively battle Sith-tainted soldiers and Sith-spawned monstrosities.”

Another such group, "that fought with the Jedi Knights and the armies of the Old Republic during the Clone Wars" are the Pandarran Warriors, led by Gendal Delan. Although, no licensed work confirms that the Antarian Rangers were inspired by either organizations, the Wookieepedia team makes a strong case on the permanence of systematic organized help for the benefit of the Jedi Order in the Star Wars narrative.

Sources: X-wing: Wraith squadron (p.185), Rules of Engagement: The Rebel SpecForce Handbook (p.4) – Freedom Warriors also appear in Tales of the Jedi Companion (p.173), Wanted by Cracken (pp.62-64)