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National Bird Day: Why Birds Matter to Us

National Bird Day is celebrated every year on 5 January . This day is observed to spread awareness about birds, their importance in nature, and the need to protect them. Birds are beautiful living beings and play a very important role in keeping our environment healthy. Origin of National Bird Day National Bird Day was first celebrated in the year 2002 . It was started by bird lovers and environmental groups to protect birds from dangers like deforestation, pollution, and illegal hunting. The main aim of this day is to teach people, especially students, why birds are important and how we can help save them. Why Is National Bird Day Celebrated Every Year? National Bird Day is celebrated every year because many bird species are disappearing due to human activities. Cutting trees, using plastic, pollution, and climate change are harming birds and their homes. This day reminds us that: Birds need protection Nature should be respected Everyone has a responsibil...
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Resonators | Cavity resonator | Microwave electronics

Resonators

Resonators

  • It is found that any distributed transmission line of length λg/2 will resonate, if it is shorted or open at one end. This is the principle of resonators.
  • A resonator is actually a device or a system that exhibits resonance or resonant behaviour. It means it naturally oscillates at some frequencies with greater amplitude than at other frequencies.
  • The frequencies at which the device oscillate are known as resonant frequencies.
  • The oscillations produced in a resonator can be either electromagnetic resonance or mechanical resonance.
  • The resonators are used to generate either waves of specific frequencies or to select specific frequencies from a signal.
  • The musical instruments use acoustic resonators and it produce sound waves of specific tones.

    • Resonance

  • The resonance is a phenomenon that consists of a given system, which is driven by another vibrating system or by external forces to oscillate with greater amplitude at some particular preferential frequencies.
  • The resonance occurs, when a system is able to store and easily transfer energy between two or more different storage modes.

Cavity Resonator

  • The cavity resonators are devices, which is closely related to waveguides and have the practical importance.
  • If the waveguide is limited by closing the ends of a finite length of the tube in conducting surfaces then it is known as cavity resonator.
  • The cavity resonators produced by placing end faces on finite length of cylindrical tube waveguides are known as cylindrical cavity resonators.
  • There are two types of cylindrical cavity resonator, one is rectangular and another is circular. It depends on the cross section of the cavity resonator.

Cylindrical cavity resonator

  • In cylindrical cavity resonator we assume that
    • The end faces of cylindrical cavity resonators are plane, and perpendicular to the axis of cavity.
    • The walls of cylindrical cavity resonators are perfectly conducting.
    • The transverse cross sectional shape and size of it are uniform.
    • The cavity of cylindrical cavity resonator is filled with loss-less non-conducting medium.
  • In cylindrical cavity resonator, electromagnetic wave propagates along the axis of the cavity and they reflects back and forth by the plane end faces.
  • Both waves i.e., incident wave and reflected wave of cavity resonators superpose, and form a system of standing waves.
  • It is found that the certain standing wave field distribution can be set up in the cavity corresponds to different cavity modes.
  • The possible mode of frequencies of cylindrical cavity resonators are known as resonant frequency of the cavity.
  • It is also found that the cavity resonator show the properties like an electronic resonant circuit i.e.,
    • They can store energy in oscillating electric and magnetic fields.
    • They can dissipate a fraction of the stored energy in each cycle of oscillation.

Advantage of cavity resonator over LC circuits

  • The fraction of the stored energy dissipated per cycle of cavity resonator is about 1/20 the fraction dissipated per cycle in L-C circuit.
  • The resonant frequencies of cavity resonator ranges from few megacycles. This range is impossible in LC circuit.
To know more about this lecture please visit on https://youtu.be/VmtLNlu6aOs
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