In this study we aim at improving the homogeneity of the magnetic field inside a microwave resonator cavity designed in line with the development of a novel, high performance frequency standard. We study the effect of modified boundary conditions applied to a cavity based on a loop-gap geometry, and demonstrate the high potential of this cavity to improve the frequency stability. Our concept is suitable for the future generation of compact, high-precision frequency standards based on vapor cells and pulsed optical pumping regime (POP atomic clocks). These novel clocks are excellent candidate for future applications in space or mobile applications where highly compact instruments are required.