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BlogsAsk The Experts ForumIs There a Relationship Between the Read Range and Gain of an RFID Antenna?

Is There a Relationship Between the Read Range and Gain of an RFID Antenna?

Posted By RFID Journal, 08.24.2016

If so, what does a higher gain mean for the antenna's range?




Yes, there is. An antenna's gain is a measure of the amount of power transmitted in a specific direction. A higher gain essentially means more energy is emitted and thus reaches the tags, allowing them to transmit a further distance.

—Mark Roberti, Founder and Editor, RFID Journal


James E. Heurich 2016-09-28 10:19:43 AM
Absolutely, the greater the gain, the more range will be achieved, but there are legal limits depending on the country and governmental regulations. The amount of power available at the Reader's Antenna port and the gain of the Antenna combine to determine what is known as EIRP. In the USA, the maximum allowable is 4W EIRP. You can find many EIRP calculators online. If a Reader outputs 1W of TPO (total power output) (which can also be expressed in DBM's) then the maximum Antenna gain in order to remain under 4W EIRP is 6dBi. Most Readers have adjustable TPO/DBM, so if you were interested in using an 8 or 12dBi Antenna, you'd need to adjust that power back in order to meet the guidelines. Another factor in the EIRP calculation is the amount of resistance present due to the length and diameter of the Antenna cable. The smaller the diameter and the longer the length of the cable, the more power is lost once the energy reaches the Antenna.

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