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G: the antenna gain; is the magnetic constant; is the electric constant; For antennas which are not defined by a physical area, such as monopoles and dipoles consisting of thin rod conductors, the effective length (units: meter) is used to measure the ratio between voltage and electric field.
The Foltz drawing pin like antenna from 1998 size 0.62 and 22% bandwidth. The Rogers cone from 2001 is size 0.65 and right on the limit. Lina and Choo planar spirals in size ratios range from 0.2 to 0.5; The fractal Koch curve antenna approaches the limit. [5] A meander line antenna optimizes the size for narrower bandwidths of the order 10%. [11]
The latter factor is quantified by the antenna gain, which is the ratio of the signal strength radiated by an antenna in its direction of maximum radiation to that radiated by a standard antenna. For example, a 1,000 watt transmitter feeding an antenna with a gain of 4× (equiv. 6 dBi) will have the same signal strength in the direction of its ...
A parameter often encountered in specification sheets for antennas that operate in certain environments is the ratio of gain of the antenna divided by the antenna temperature (or system temperature if a receiver is specified). This parameter is written as G/T, and has units of dB·K −1. G/T Calculation. G/T is the figure of merit for a ...
Antenna directivity is the ratio of maximum radiation intensity (power per unit surface) radiated by the antenna in the maximum direction divided by the intensity radiated by a hypothetical isotropic antenna radiating the same total power as that antenna. For example, a hypothetical antenna which had a radiated pattern of a hemisphere (1/2 ...
Usually, a factor k is used in the equation above, modified to be k > 1 means geometrically reduced bulge and a longer service range. On the other hand, k < 1 means a shorter service range. Under normal weather conditions, k is usually chosen [5] to be 4 ⁄ 3. That means that the maximum service range increases by 15%.
But the noise factor F ase is not the SNR degradation factor in any optical receiver. All the above conflicts are resolved by the optical in-phase and quadrature noise factor and figure F o,IQ. [9] [10] It can be measured using a coherent optical I&Q receiver. In these, power of the output signal is proportional to the square of an optical ...
For long delay multipath, the receiver itself can recognize the wayward signal and discard it. To address shorter delay multipath from the signal reflecting off the ground, specialized antennas (e.g., a choke ring antenna) may be used to reduce the signal power as received by the antenna. Short delay reflections are harder to filter out because ...