SAR instruments with multiple channels offer a variety of operation modes. The trade-space includes the instrument and antenna parameters designed to enable various techniques (operation mode). The trade parameters are utilized to achieve a required SAR performance satisfying the mission and user requirements. Finding a solution in this multi-dimensional trade space of inter-dependent parameters is not trivial and often involves compromise of parameters. This paper addresses the topic of conceptual SAR instrument design tailored to a set of operation modes. It explains SAR techniques utilizable to achieve a required performance, shows the consequences for the conceptual multi-channel instrument design, and details possible compromises between performance and complexity.