The disclosed reader is composed of antenna, directional coupler, logarithmic amplifier, two pieces of A / D converter, digital signal processor, power amplifier, frequency synthesizer, and serial interface etc. using orthogonal non coherent demodulation technique, the reader receives and detects data information (amplitude modulation or phase modulation) carried by backscattering electromagnetic wave of ID label in radio frequency. Thus, the invention omits complex phase-lock circuit of local oscillation of receiver as well as realizes higher sensitivity of receiver, and longer distance for reading card. Using directional coupler and logarithmic amplifier, the power amplifier carries out automatic power control. Comparing with traditional ID label reader in UHF, the disclosed reader possesses advantages of simple structure, stable performance, and low price.