This paper presents a method for proactive robot communication connectivity maintenance based on electromagnetic field (EMF) recognition and signal strength (SS) gradient estimation for mobile robots. To achieve these goals in an efficient manner, we combine EMF recognition method and gradient descent of SS measurements into a proactive robot motion control algorithm in a way that maintains connectivity among mobile robots in the presence of a radio frequency (RF) obstacle. The EMF recognition method utilizes hidden Markov models (HMMs) for learning EMF environments based on SS measurements. The proposed motion control algorithm uses the EMF recognition and gradient method results to drive the robots towards favorable locations in which robots can communicate. The numerical simulation demonstrates promising EMF recognition, robot motion control results and confirms their abilities in proactive robot motion control for connectivity maintenance.