An apparatus for determining alignment of a first subsystem relative to a second subsystem. The apparatus includes a first antenna system for simultaneously transmitting a delta pattern radiation beam at a first frequency and a sum pattern radiation beam at a second frequency. The apparatus also includes a second antenna system for receiving the delta pattern radiation beam at the first frequency and the sum pattern radiation beam at the second frequency. The apparatus also includes a processor to process the received delta pattern radiation beam and sum pattern radiation beam to determine if a predetermined alignment criterion between the first antenna system and the second antenna system is satisfied.