find the radiation resistances of a circular loop antenna of radius 0.3133 meter operating at1m?
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Answer:
Radiation resistance is that part of an antenna's feedpoint electrical resistance that is caused by the radiation of electromagnetic waves from the antenna.[1] In radio transmission, a radio transmitter is connected to an antenna. The transmitter generates a radio frequency alternating current which is applied to the antenna, and the antenna radiates the energy in the alternating current as radio waves. Because the antenna is absorbing the energy it is radiating from the transmitter, the antenna's input terminals present a resistance to the current from the transmitter. Unlike other resistances found in electrical circuits, radiation resistance is not due to the opposition (resistivity) of the material of the antenna conductors to electric current; it is a virtual resistance due to the antenna's loss of energy as radio waves.[2][1] The radiation resistance {\displaystyle R_{\text{R}}}{\displaystyle R_{\text{R}}} can be defined as the value of resistance that would dissipate the same amount of power as radiated as radio waves by the antenna with the antenna input current passing through it.[3][2][4] From Joule's law, it is equal to the total power {\displaystyle P_{\text{R}}}{\displaystyle P_{\text{R}}} radiated as radio waves by the antenna divided by the square of the rms current {\displaystyle I_{\text{rms}}}{\displaystyle I_{\text{rms}}} into the antenna terminals:[4] {\displaystyle R_{\text{R}}=P_{\text{R}}/I_{\text{rms}}^{2}}{\displaystyle R_{\text{R}}=P_{\text{R}}/I_{\text{rms}}^{2}}.[5]