Coaxial cables provide the necessary connection between the RFID reader and the antenna. They can also be used to connect auxiliary devices, such as antenna concentrators and multiplexers. The energy generated by the reader is transmitted through the antenna connector on the reader, connector, coaxial cable to the connector and antenna connector in the antenna. The better quality coaxial cable (insulation quality, shield, core type), the lower the energy loss during the process. Energy losses occur in any system, it is important to know how they are dealt with in order to reduce them. When choosing a cable, you should consider:
Length – the longer the cable, the further the distance the energy has to cover. No antenna cable is perfectly insulated, so the further energy moves, the more energy is lost. If it is necessary to use a long cable, it is important to use the appropriate level of insulation required to minimize losses.
Insulation indicator – the higher the insulation rating, the thicker and more protected the cable is. The most commonly used coaxial cables in the UHF frequency range are 195, 240 and 400. The disadvantage of a thicker, more insulated cable is that it is less flexible and can be difficult to install in tight places requiring its bending.
Connectors – located on both ends of the cable, and their type is defined by connectors in the reader and antenna. The most popular types of connectors are: TNC, RP-TNC, SMA, RP-SMA, N-type, BNC. The connector can be in the so-called feminine or male version.
Most stationary RFID readers have a GPIO port that allows you to connect additional devices such as signaling columns, motion detectors, sound columns, LED counters, etc. These devices provide additional functionalities that can improve the RFID solution. In each GPIO port, there are several physical pins or pins that we use to transmit signals. The signal has only two settings, the so-called high and low condition. For example, a high state may act as a trigger for an external device to which we send a signal to run it. Similarly, the incoming high state from an external device may act as a trigger, which the reader will use to perform a predetermined operation. The number of pins / pins in the GPIO port varies depending on the RFID reader. It is important to know in what range the voltages work GPIO inputs / outputs. Some GPIO ports do not generate enough voltage to power the external device. In this case, although the reader has a GPIO port, an additional GPIO box is used, which is connected to the port on the reader. These boxes provide convenient access, easier to “wire” external devices and provide them with the right power supply.