V.S.W.R., which stands for the English term "Voltage Standing Wave Ratio", in English referred to as the voltage standing wave ratio (PSV or CSV), is a technical parameter that indicates how effectively the antenna is matched to the coaxial cable and to the LTE modem or router. The LTE modem sends a signal to the antenna that carries some energy. Ideally, the antenna radiates all this energy into the surrounding area. However, if the antenna and the rest of the system, especially the cable, are not properly impedance matched, some of the signal will bounce off the antenna and travel along the cable back to the modem. It is the degree of this reflection that is described by the V.S.W.R. This is a ratio where perfect matching without any reflection is expressed as a 1:1 value. However, such a condition is almost unattainable in practice. For LTE antennas, a V.S.W.R. of less than 1.5:1 is considered an excellent value. Values up to 2:1 are still considered acceptable for most common installations. However, if the value is higher, for example 3:1 or more, it means that a significant amount of power is reflected back. This reflected power is not only not radiated, resulting in a weaker signal and thus lower connection speed and stability, but it also returns to the transmitting part of the modem where it can be converted into heat and potentially damage the equipment. A low V.S.W.R. value is therefore an indicator that the antenna system is properly installed and operating at high efficiency.
