Antenna efficiency is different from and contrasted with radiation efficiency, which applies to any antenna type.
2.
As a broadband antenna, the T2FD will normally display a reasonably low SWR does not mean high antenna efficiency.
3.
Antenna efficiency, ?, is a term associated with aperture antennas, e . g ., parabolic dishes.
4.
The resistor network exception was created to allow stations to reduce their antenna efficiency without having to modify the existing tower.
5.
Note that antenna efficiency is a separate issue from impedance matching, which may also reduce the amount of power radiated using a given transmitter.
6.
Series-fed monopole antenna sites require care, keeping weeds as short as possible, since weeds will dissipate radio frequency power, severely reducing antenna efficiency.
7.
Thus, the effective area of an aperture antenna is the surface area of a theoretically perfect aperture that would collect the same energy as the actual aperture with associated antenna efficiency.
8.
Contrast this tiny component to the massive and very tall towers used at AM broadcast stations for transmitting at the very same frequency, where every percentage point of reduced antenna efficiency entails a substantial cost.
9.
"' Partial directivity "'is calculated in the same manner as the partial directive gain, but without consideration of antenna efficiency ( i . e . assuming a lossless antenna ).
10.
However, in the case of a directional antenna used for receiving signals with the intention of " rejecting " interference from different directions, one is no longer concerned with the antenna efficiency, as discussed above.
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