AM TRANSMITTER

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AM TRANSMITTER In an  AM  ( amplitude modulation )  transmitter  the amplitude (strength) of the carrier wave is varied in proportion to the modulation signal. In an FM (frequency modulation)  transmitter  the frequency of the carrier is varied by the modulation signal. There are two basic configuration for transmitters. High level modulation low level modulation  High level modulation In high power modulation signal,the carrier voltage is modulated at highest power level.the require power level is obtained by class c power amplifier.The block diagram of high level modulation as shown in fig(a). low level modulation In the low level modulation system, the carrier is modulated at low power level and the carrier power is subsequently raised to the desire level in the class B amplifier . transmitters using high power level are widely use at present .The block diagram of high level modulation as shown in fig(b). advantage AM sign
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E TYPE TEE JUNCTION

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E TYPE T JUNCTION


An e type t junction as shown in fig.1.It is an  E type T junction because the junction arm extends from the main waveguide in the in the same direction as the E field in the waveguide.


fig.1.


In the E type t junction  the E field for various input as show in fig.2.The  E type T junction with inputs fed into the various arms.The magnetic  lines that always present with an electric field have been omitted. In view (k), the input is fed into arm b and the outputs are taken from a and c arms. when the E field arrives between points 1 and 2 ,point 1 becomes positive, and 2 becomes negative. The positive charge at point 1 induce a negative charge on the wall 3.The negative charge at point 2 induces a positive charge  at point 4 .These charges cause the fields to form 180 degrees out of phase in the main waveguide; therefore, the outputs will be 180 degree out of phase with each other. In view l, 2 in phase inputs of equal amplitude are fed into the a and C arms .The signals at point 1 and 2 have the same phase and amplitude. no difference of potential exist across the entrance to the b arm and no energy will be coupled out. however, when the two signals fed into the a and c arms are 180 degree out of phase ,as shown in the view M. points 1 and 2 have a difference of potential. This difference of potential induces and E field from point 1 to point 2 in the b arm, and energy is coupled out of this arm.  View n and p set two methods of obtaining two outputs with only one input.






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