Circular Vs. Linear polarized antennas

By Times 7, Dec 12, 2022

When choosing a suitable RFID antenna for your application, the polarization of your antenna is a key consideration, as polarization can influence the performance of your RFID read zone. 

We have a wide range of circular and linear polarized antennas, but how do you know which is right for your application? We have broken down the key differences between each polarization type on how they operate and some best use cases. 

Circular polarized antennas 

A circularly polarized RFID antenna emits electromagnetic waves that rotate azimuthally to the propagation direction. Antennas can have a right-hand circular polarization or a left-hand circular polarization. Right or left determines the direction of the rotation. Circular polarization is formed by two wavelengths from an antenna's far-field region.

Near-field electric and magnetic fields have a complex relationship that becomes more predictable as they get farther away. If the electric and magnetic fields are complex, the radiation doesn't have a polarization; unpredictable electric and magnetic fields communicate with the tag. Antennas with circular polarization typically have a lower gain and a larger half-power beamwidth (HPBW). If the tag's orientation is not controlled, a circularly polarized antenna can be necessary to excite the tag. Due to their low gain and high HPBW, circular antennas can also be an effective option when a short but wide read window is needed. 

Best use cases: 

• Inbounds/Outbound Processes  

• Inventory tracking 

• Retail   

Linear antennas 

Linear polarized antennas do not rotate, so the tag will only be able to receive maximum power when it is oriented correctly in relation to the antenna. However, reflective environments, such as refrigerators and metal cabinets, can reliably excite tags when reflected signals are available. A linear antenna usually has a higher gain and narrower beamwidth, making it ideal for long-range applications, controlled read-window applications, and manufacturing lines (consistent tag orientation).  

Best use cases: 

• Parking Management 

• Food, Meat, and Chemical Manufacturing Processes 

• Industrial applications  

It is essential to consider polarization when choosing an RFID antenna, as it can help maximize read zone performance. For most applications, circular polarized antennas are preferred since they are less affected by alignment. Contact our team for more information on which antenna is suitable for your application. We are here to help!