Electromagnetic Field Coupling between a Probe and a Rectangular Aperture Mounted on Open-ended Cavity

This paper presents the electromagnetic-field coupling between a probe and rectangular aperture mounted on open-ended cavity. The field characteristics of the rectangular aperture primarily depend on the mode distribution of the electromagnetic field inside the structure. The significant parameters that have strong influence to the mode distribution are the size of the aperture cross section, the length of the cavity, the location and the length of the probe. In the design, the aperture cross section should be selected to let only specified mode can be propagated. However, when the probe is contained inside the cavity, the discontinuity inside the cavity is occurred that makes the field distribution to be disturbed. Therefore, the mode distribution becomes complex in the vicinity of the probe. The mode truncation for various distances from the probe is necessary in order to accomplish the accurate results to find the radiation characteristics. The criteria for the mode truncation are first specified to yield efficient field solution. Subsequently, the finite number of the mode summation is determined to achieve the convergent condition. Furthermore, the radiation characteristics are obtained by using the dyadic Green function. The results from this work are significant to further design of this structure in the microwave and millimeter wave devices