Application of hybrid radiation modes of a microstrip line in the design of rectangular microstrip antennas

The design of rectangular microstrip antennas is presented. The resonant frequency of a rectangular microstrip antenna is found as the frequency for which the current corresponding to a single hybrid radiation mode of microstrip line reaches maximum value. The finite transversal dimension of the antenna is taken into account by introducing a correcting term that depends on the effective dielectric constant of an equivalent microstrip line. Numerical results confirming the accuracy of the approach (error <1% for thin substrates) are presented. An application example of the method for studying mutual coupling between antennas is also shown. Limitations and prospects for the future of the method are discussed