Given a general elliptically polarized wave as per Eq. (93):

E_s = [E_x0a_x + E_y0e^jϕa_y ]e^−jβz

(a) Show, using methods similar to those of Example 11.7, that a linearly polarized wave results when superimposing the given field and a phase-shifted field of the form:

Es = [E_x0a_x + E_y0e^−jϕa_y ]e^−jβze^jδ

where δ is a constant.

(b) Find δ in terms of ϕ such that the resultant wave is linearly polarized along x.