The reader developed by our company requires the external antenna to be short-circuit antenna, that is, the antenna with zero dc impedance. The following indexes are mainly considered in the selection of microwave antenna:
1.Operating frequency: the highest transmitting and receiving efficiency of the antenna is required within the frequency range. The current antenna operating frequency range is: 902~928MHz/865~868MHz.

2.Gain: refers to the amplification factor of the transceiver signal. Generally, the higher the gain is, the farther the distance between reading and writing labels is. The stronger the direction; And the bigger the antenna. The range of options is between 5dBi and 15dBi.

3.Standing wave ratio: the reflection of the antenna to the transmitted signal, the smaller the better. Generally it should be less than 1.4.

4.Polarization direction: refers to the relationship between the electric field vector of the antenna emitting electromagnetic waves and the ground. There are two kinds of linear polarization: horizontal polarization and vertical polarization.

5.Beam width: refers to the range of electromagnetic radiation emitted by the antenna.