Backscatter communication with amplitude modulation is promising for facilitating cost-effective and low-power transmission in Internet of things (IoT). Various backscatter communication systems with amplitude modulation have been investigated in the latest work. One critical issue is that only when the tag is placed in certain positions within the communication range can the system achieve good communication performance, where poor performance is seen in other blind zones. In this article, we address the blind zone problem in backscatter communications with amplitude modulation, and analyze the problem according to the Fresnel zone theory. We also design and implement real-time systems employing multi-antenna transmission and multi-receiver reception to deal with the blind zone problem. Experimental evaluation has verified that multi-receiver reception can improve the communication coverage with greatly decreased blind zone, and that the multi-antenna technique can facilitate full backscatter communications with no blind zone.