Radiation From High Frequency Printed Circuits

• Published in: 9th International Zurich Symposium and Technical Exhibition on Electromagnetic Compatibility pp. 625 - 630
• Main Author: Gardiol, Fred
• Format: Conference Proceeding
• Language: English
• Published: IEEE 12.03.1991
• Subjects: Conductors; Couplings; Dielectrics; Integrated circuit modeling; Microstrip; Microstrip antennas; Solid modeling; Substrates; Surface impedance; Surface waves
• ISBN: 9781509031948; 1509031944
• DOI: 10.23919/EMC.1991.10781017

Printed circuits are open structures, that may radiate as the frequency of the signals increases within the microwave range. Radiation becomes significant in the vicinity of discontinuities and when the structures are resonant, which is the situation encountered in the design of filters. The mechanism of radiation is linked to the excitation of three kinds of waves : the radiated waves, produced by the currents flowing on the top side of the upper conductor, while the current on the lower side excites leaky waves (that contribute mostly to radiation) and surface waves. The latter remain trapped within the dielectric substrate and propagate with little attenuation, producing spurious coupling and diffraction. An analysis technique originally developed for patch antennas now provides a means to rigorously study the radiation from microstrip circuits. It is based on a mixed potential integral equation formulation (MPIE), with Green's functions provided by Sommerfeld integrals, for which an exact evaluation technique was developed. The currents flowing on the circuits are developed over subsectional basis functions, and are determined by a method of moments. This approach provides both the circuit parameters (impedance or scattering matrices), and its radiation characteristics (antenna pattern).