HJ integrals and evaluation of rectangular source integral

In this paper Hubbell's rectangular source integral H′(a, b), which is a double integral, is expressed in the form of HJ(A(a), B(b)) integral. The integral HJ(A, B) is expressed in the form of a converging series of rational parameters A and B. Here HJ(A, B) is approximated by considering first seven terms in the series and the results are found to give good results for various values of a and b which are less than or are equal to one. Results are presented for the values of a and b (.1-2 and .1-1) respectively. When the values of a and b are greater than one the integral H′(a, b) has been expressed in the form of a logarithmic function. These results are also presented in this paper. Here the values of a and b are considered from 1.0 to 10,000.0 respectively. All these results are found to agree with the results available in literature.