Systems, devices and methods provide an RF coil which produces a field having linear phase variation across an imaging volume. In one embodiment, a coil comprises multiple microstrip elements configured to have an increased effective electrical length. This increase in electrical length allows for a larger linear phase shifts over the length of the microstrip element which in turn increases linear phase variation capabilities. This may be accomplished by increasing the effective dielectric properties of the microstrip element. Increasing the effective dielectric may be accomplished by utilizing distributed capacitors along the length of a microstrip element (e.g. lumped element capacitors), by altering the materials used to fabricate the microstrip element, etc. Additionally, increasing the effective dielectric may be accomplished using a combination of these means. Embodiments may further enable linear phase variation along the imaging volume at high frequencies, such as frequencies utilized for 3 T and above MRI devices.