This thesis presents two novel dispersion engineered structures for controlling the propagation properties of EM waves. The first structure is a low-profile dielectric choke ring for multipath mitigation for GNSS applications. The proposed structure has a dual-band surface impedance resonance around the GNSS bands of L2 and L1. An in-house choke ring prototype of the proposed design was tested with the DM antenna. A high multipath rejection in both GNSS bands is experimentally confirmed with comparable performances to an otherwise bulky, heavy, and expensive conventional metallic choke ring. The second structure is an amplitude-equalized group delay device, called a phaser, for ASP applications, implemented at microwave and mm-wave frequencies. The proposed devices achieve a flat magnitude transmission while preserving their strong dispersive delay response. Both types of phasers are demonstrated using full wave simulations, with experimental demonstration currently underway for the active configurations.