Antenna operating distance could be anywhere from centimeters to over 10 meters of range BUT
Antennas can be directional or omnidirectional, antennas can be linear or circular, antennas come with different gains and in different sizes. All of these physical differences have a direct impact on operating performance of an antenna. Furthermore, also the output power settings on your reader, antenna to read cable type and length combined with the tag being used determine your functional operating distance for your RFID solution.
Because of all these variables and often your solution is not exactly the same as ‘others’ we strongly recommend to seek advice from your solution provider and include proper testing for your solution needs during a site survey before finalizing all solution components.
Antenna cables connect a chosen antenna with a chosen reader, this all sounds pretty straightforward but does require some thinking as not all antennas and/or readers have the same standard coaxial connector. Therefore, it is important to ensure you know what type of connectors are present on your antennas and readers before you can choose the correct cable. As it is inevitable that signal loss will occur with any cable it is advisable, of course where possible, to keep cable distance short. However, this is often not possible so it becomes important to determine the cable loss for the length required to still warrant the desired read performance. Cable loss is directly related to insulation rating of the chosen coax cable most common insulation series are show in the cable insulation rating insights below
Important note: check cable installation instructions more specific allowed bend radius for each of the low loss cables as incorrect installation will impact performance/loss of the cable in a negative way.
Choice of connector is often already defined by the vendors/suppliers of the readers and antennas. Coax connector types could be BNC, TNC, SMA or N-type. Each of those connectors while have a male or female version, male has a pin and inside threading whereas a female has a hole and outside threading. Few connectors such as SMA and TNC come sometimes in reverse polarity and are references RP-SMA or RP-TNC, for those connectors the male will have a hole and the female a pin.
Determination what the maximum allowed cable length is often done with a cable loss calculator – such a calculator allows to select cable series, antenna type and set reader output power and show the estimated output power at the antenna point.
Omnidirectional antennas will emit the signal 360 degrees around themselves. These antennas typically have a shorter range. These antennas might be used when the RFID signal needs to be picked up with discrimination on which side or which direction.
Directional antennas will emit the signal in a very particular direction based on its design with very little ‘backside’ radiation. This permits to cover a specific area / zone, they are also more suitable in solutions where direction is relevant. Directional antennas typically have a horizontal as well as a vertical ‘opening’ angle to where the signal is radiated.
Antennas can have a specific antenna gain which often is expressed in dbi. Antenna gain could help increase read range, but when gains go up very often the antennas becomes more directional (smaller opening angle) Important note to make valid in general for ALL RFID installations but more in particular relevant when using high gain antennas is to ensure local regulatory is respected and no more power then allowed is emitted at the antenna level.
Antennas can be linear or circular. When linear antennas are used tag vs antenna orientation is really important to achieve best range performance where as when circular antennas are used there is a higher tolerance on tag vs antenna orientation making the solution more robust.
Antennas can be designed for indoor or outdoor the exact environmental exposure are indicated in what is referenced their IP-rating (international protection mark). This rating in most cases has 2 figures of which the first figure indicates its resistance to dust and the second water/liquids.
Antennas can be external (most cases) or could be integrated within the reader.
