With the continuous shrinkage of the minimum feature sizes of semiconductor integrated circuits and their packages along with the increase in the operating frequency have caused parasitic electromagnetic (EM) coupling to become a serious design concern. Realizing the significant role of EM coupling in influencing the system and device-level radio frequency (RF) performance entails a good understanding of the coupling mechanism occurring in a certain EM environment. EM coupling between the circuit elements can be considered as a desirable or undesirable phenomenon depending upon the intended application, the intrinsic EM structure, and components forming the RF circuit. EM coupling is necessary for the design of coupled microwave structures such as coupled line filters, couplers, microwave baluns, and several other distributed circuits. In other cases, however, EM coupling is not beneficial and considered as a source of EM interference (EMI) that can drastically impact the electrical performance of the circuit.