Generating Multiple Simultaneous Beams in transmit mode with ADAR1000


I can generate multiple simultaneous beams in receive mode using ADAR1000 by inserting power splitters after LNAs. In this scheme, each receive beam is making use of full antenna array. However, I haven’t been able to achieve this function in transmit mode. Reason is that when I apply different sets of phase shifts (corresponding to different beam directions) to my antenna array, I get only one beam in the direction that corresponds to the the net phase-shifts applied to the array. For example, If 0 deg and 10 deg phase shifts correspond to Beam direction of 30 deg  for a two-element array,  and 0 deg and minus 10 deg correspond to Beam direction of minus 30 deg for the same array, then applying both sets of phase shifts simultaneously to that array is producing one beam that is in broadside direction ( corresponding to net phase shifts of 0 deg at both antenna elements). My target was to get two simultaneous beams, one in the direction of 30 deg and other in the direction of minus 30 deg. 

Let me further explain my issue with a real example. I have an 8-Element Linear Array. I want to generate two simultaneous beams in transmit mode using ADAR1000. One way of doing it is that I divide my linear array into two sub-arrays and then apply appropriate phase-shifts to these sub-arrays through two separate ADAR1000 ICs. In this way I’ll get two beams in the intended directions  but directivity of each beam will be half that of a beam that uses the full array. I want to produce multiple simultaneous beams in transmit mode where each beam makes use of the full array so that the directivity of each beam is not sacrificed. Literature says that this is definitely possible with all-digital beamforming. Can I achieve this goal using Analog Beamforming and ADAR1000?  

Any help in this regard will be highly appreciated! Thanks.