Leaky wave antenna is known as a type of travelling antenna with dispersive frequency responses, which has found important applications in modern communication, imaging and radar systems. The beam scanning rate is a key consideration in some applications, since it can minimize the bandwidth requirement of the system, during the scanning in broad angular regions. However, the sweeping linearity, namely the scanning angular range per unit frequency, is seldom taken into account at the same time in the published literature. In this article, we propose a waveguide-type leaky-wave antenna working from 11.1 GHz to 12 GHz. By loading periodical pins with glide symmetry in the waveguide, it is possible to manipulate the dispersion properties of the fast wave mode, hereby giving rise to a good balance between the scanning rate and sweeping linearity. This scenario has been validated by numerical simulation and experiment with excellent agreement. The measurement results reveal that the scanning angles have been increased to range from 16.7° ~67.5° varying the frequency from 11.1 to 12.1 GHz. The relative average scanning rate is enhanced up to 589.3°, with high sweeping linearity.