An improved catheter system having an ultrasonic imaging transducer coupled to a drive cable disposed within a lumen of a flexible tubular catheter body. The support board body is formed with at one preloading groove in the side subjected to the compressive stress. A detection scheme is performed to detect the marker associated with the microparticle and the identity of the probe, and any target bound to the probe. Long-stalked straw is deposited in a swath for later use, and short-stalked straw and chaff are discharged out of the agricultural harvester separate from and without whirling up again the crop swath.