AbstractAn investigation is made of resonant excitation of helicon waves at the difference frequency of two microwave beams propagating in a magneto‐active solid state plasma viz. n‐InSb. The two beams propagating obliquely with the magnetostatic field interact in the semiconductor to give rise to a nonlinear ponderomotive force at the difference frequency which resonantly excites helicon waves if the dispersion relation corresponding to helicon waves is satisfied. The results show that microwave beams of power densities 1 MW cm−2can excite helicon waves of power density 0.98 kW cm−2when ωc/ω = 25. The power carried by helicon waves depends on the direction of propagation of the pumps relative to magnetostatic field. For the parameters under consideration the power gets optimised at an angle θ = 63.4°. Helicon waves are not excited if the pumps propagate parallel or perpendicular to the magnetic field. The increase in magnetic field increases the power density of the excited h