Butler matrix for harmonic radar application

This paper presents a Butler matrix for harmonic radar application. The proposed Butler matrix has the same beam directions in the two different frequencies and the higher frequency can be the double of the lower frequency. Therefore, it can be implemented on the harmonic radar for beam steering function. The Butler matrix is composed of wideband couplers, and dual band phase shifters. With reflection type phase shifter and stepped impedance resonators. The phase shifter can have different phase shifts in the two frequencies and make the Butler matrix have the same direction in the two operation frequency.