A NEW SCALAR TRANSITION FINITE-ELEMENT FOR ACCURATE ANALYSIS OF WAVE-GUIDES WITH FIELD SINGULARITIES

When the scalar Helmholtz equation is solved by Finite Element Method, a slow rate of convergence and inaccurate results can be found if wav eguides containing field singularities are analyzed. By using singular elements around the singularity, an important improvement is attained , but when the size of the singular elements is too small, the correct modeling of the fields is lost, In this paper we introduce a new fami ly of transition finite elements that represents a behavior of the axi al field component of the form O(r(lambda)), with any O < lambda < 1, for singular points placed outside the element. By employing these tra nsition elements adjacent to singular elements, the loss of the singul ar modeling of the fields is avoided.