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What type of antenna used in the mobile?

Answer is Omni directional antenna used in the mobile. There are various types of antenna used in mobile like, PIFA (Polar Inverted F Antenna) FICA etc

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Radar Equation

The power Pr returning to the receiving antenna is given by the radar equation:

P_r = {{P_t G_t A_r \sigma F^4}\over{{(4\pi)}^2 R_t^2R_r^2}}

where

  • Pt = transmitter power
  • Gt = gain of the transmitting antenna
  • Ar = effective aperture (area) of the receiving antenna
  • σ = radar cross section, or scattering coefficient, of the target
  • F = pattern propagation factor
  • Rt = distance from the transmitter to the target
  • Rr = distance from the target to the receiver.

In the common case where the transmitter and the receiver are at the same location, Rt = Rr and the term Rt² Rr² can be replaced by R4, where R is the range. This yields:

P_r = {{P_t G_t A_r \sigma F^4}\over{{(4\pi)}^2 R^4}}.

This shows that the received power declines as the fourth power of the range, which means that the reflected power from distant targets is very, very small.

The equation above with F = 1 is a simplification for vacuum without interference. The propagation factor accounts for the effects of multipath and shadowing and depends on the details of the environment. In a real-world situation, pathloss effects should also be considered.

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Friday, February 18, 2011

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1 comments:

  1. Great list, thanks for sharing this nice info... :-)

    ReplyDelete

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Diagram Of Klystron amplifier And Types

A klystron is a specialized linear-beam vacuum tube (evacuated electron tube). Klystrons are used as amplifiers at microwave and radio frequencies to produce both low-power reference signals for superheterodyne radar receivers and to produce high-power carrier waves for communications and the driving force for modern particle accelerators.

Klystron amplifiers have the advantage (over the magnetron) of coherently amplifying a reference signal so its output may be precisely controlled in amplitude, frequency and phase.


Preview
Types

1.Two-cavity klystron amplifier
Klystron.enp.gif
2.Two-cavity klystron oscillator
3.Reflex klystron
Reflex.sch.enp.svg
4.Multicavity klystron
5.Tuning a klystron
6.Optical klystron
7.Floating drift tube klystron

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