The effects of calcium substitution on the structural and microwave dielectric characteristics of [(Pb1-xCax)(1/2)La-1/2](Mg1/2Nb1/2)O-3 ceramics (with x = 0.01-0.5) were investigated. All the materials were observed to have an ordered A(B1/2B1/2)O-3-type perovskite structure; however, the space group of the structure changed from Fm3m to Pa3 as the calcium content increased to x = 0.1, and then from Pa3 to R3 at the x = 0.5 composition. During the structural evolution, the lattice parameter of the perovskite cell decreased linearly, and the dielectric constant (k) also decreased, from k = 80 to k = 38, However, the product of the quality factor and the resonant frequency (Q x f) increased from 50000 GHz to 90000 GHz as the calcium content increased. Also, the temperature coefficient of resonant frequency (tau (f)) gradually changed from 120 ppm/degreesC to -40 ppm/degreesC as the calcium content increased. At the x = 0.3 composition, a combination of properties-k approximate to 50, Q x f approximate to 86000 GHz, and tau (f) approximate to 0 ppm/degreesC-can be obtained.