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Increasing return loss corresponds to lower SWR. Return loss is a measure of how well devices or lines are matched. A match is good if the return loss is high. A high return loss is desirable and results in a lower insertion loss. From a certain perspective 'Return Loss' is a misnomer. The usual function of a transmission line is to convey ...
In antenna theory, radiation efficiency is a measure of how well a radio antenna converts the radio-frequency power accepted at its terminals into radiated power. Likewise, in a receiving antenna it describes the proportion of the radio wave's power intercepted by the antenna which is actually delivered as an electrical signal.
The first term in the formula is just the electrostatic field with retarded time. The second term is as though nature were trying to allow for the fact that the effect is retarded (Feynman). These two terms describe the near field of an antenna.The third term is the term that accounts for the far field of antennas.
In real systems, relatively little loss is due to mismatch loss and is often on the order of 1dB [dubious – discuss]. According to Walter Maxwell [2] mismatch does not result in any loss ("wasted" signal), except through the transmission line. This is because the signal reflected from the load is transmitted back to the source, where it is re ...
When the antenna is fed at some other point, the formula requires a correction factor discussed below. In a receiving antenna the radiation resistance represents the source resistance of the antenna, and the portion of the received radio power consumed by the radiation resistance represents radio waves re-radiated (scattered) by the antenna. [8 ...
Note that for passive two-port networks in which |S 11 | ≤ 1, it follows that return loss is a non-negative quantity: RL in ≥ 0. Also note that somewhat confusingly, return loss is sometimes used as the negative of the quantity defined above, but this usage is, strictly speaking, incorrect based on the definition of loss. [20]
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Neglecting transmission line loss, these ratios are identical. The power standing wave ratio (PSWR) is defined as the square of the VSWR, [3] however, this deprecated term has no direct physical relation to power actually involved in transmission. SWR is usually measured using a dedicated instrument called an SWR meter.