Physics Loop Antenna Magnetic Field Question? - magnetic antenna physics
Building a TV antenna from the ground up, and you want to use a diameter of 8 cm from the antenna loop of copper in the design. They know that the TV signal most of the stations in their vertical polarization, and that most are transferred in a mountainous NE Loop. A representative of the TV station broadcasts on a frequency of 195 MHz amplitude variations of the electric field due to the location of the station signal is above 30 V / m.
a) What is the magnitude and direction of the magnetic field variations on the television in your area?
b) Explain how your antenna must be oriented to receive the maximum signal.
c) amplifier to the antenna design is needed to predict the Voltage can be measured between points A and B, if there is a small gap between the points. Use the information provided by the representative of the station to see that people expect the maximum voltage that can be between 2 points.
d) Draw the magnetic field is many times higher than the magnetic field of the television, and is in the direction of almost the same spot aligned. Explain why not result in Earth's magnetic field about issues with your antenna.
Thursday, February 11, 2010
Magnetic Antenna Physics Physics Loop Antenna Magnetic Field Question?
1 comment:
a)
The magnetic field perpendicular (to the electric field E), and the field E is vertical, as defined. The magnetic field is in the horizontal plane, with alternating peaks of NE and SE. The impedance of free space is 377ohms, and:
Z_o = | E | / | H |
| H | = | E | / Z_o = 30/377 = 080 A / M
In general, the magnetic field in the area of the rivers is expressed:
| B | = μ * | H | = 4π × 10-7 *. 08 = 1.0 * 10 ^ -7 T
b)
) The surface of the antenna (perpendicular to the section of the loop should align to the magnetic field in order to maximize the flow of linking the loop. The surface of the loop point is NW / SE, or equivalently, the sides of the loop with the non-direction are aligned.
c)
At 8 inches Diameter loop has a radius of 8 * 2.54 / (100 * 2) = 0.102m, which area is π * r ^ 2 = 032 m ^ 2
V = dφ / dt = d [B_max * A * sin (ω * t)] / dt
The degree of stress is:
| V | = B_max * A * ω = (1.0 * 10 ^ -7) * (.032) * (2 * π * 195 * 10 ^ 6) = 3.97v
This is getting a lot of RF, there is little signal amplifier, as it has done.
d)
The geomagnetic field is a steady-state (or DC) field, and since they do not vary with time of tension in the antenna loop. In addition, domestic radio and TV stations usually use filters to separate the channels of one another, and these filters significantly reduce low-frequency signal that can be induced by movement or vibration of the antenna.
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