Hand Book Of Electronics Book PDF Free Download
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ELECTRONIC DEVICES AT HIGH-FREQUENCY RANGES:
The whole of the study of the election.cs divided according to the different frequency ranges required for the various particular uses Le.
The choice of electronic circuitry for generation, amplification, transmission, and reception depends largely upon the frequency of electromagnetic waves in operation.
At high frequencies wavelength being sufficiently small, usual inductance coils and condensers cease to become useful circuit elements.
With the rise in frequency, the distributed capacitance existing between the turns of a co offers a low impedance. Consequently.
The coils act as more complex transmission lines rather than as a lumped elements with constant inductance. Further, at high frequencies, losses are increased to an appreciable proportion due to the skin effects.
Proximity effects, and radiation of energy. Condensers also meet the same fate because of distributed inductance that arises due to the linkage of magnetic flux.
At high frequencies, conventional tubes do not operate favorably and efficiently. In case of amplifier gain decreases; input impedance and the maximum impedance that can be realized in the plate circuit also decreases.
When valves operate as oscillators, even output decreases they become less efficient, and the output obtained is limited by both plate dissipation and grid dissipation at ultra-high frequencies.
The circuit reactance limitations, circuit and tube loss limitations, and electron transit time limitations are responsible for the above effects in conventional sub ea.
For transmission purposes, parallel wire lines are used at frequencies of the order of 100 mc/s. Above 200 means power loss due to radiation and induction becomes excessive.
Coaxial lines are best suited above 200 mc/s up to 3000 auc/s because their attenuation even at very high frequencies is very low.
In the micro wave, region waveguides are most suited. Their peak power capacity is greater than that of coaxial lines.
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Hand Book Of Electronics By Gupta and Kumar PDF Free Download