Found 1006 Articles for Electronics & Electrical

The FM receiver is the whole unit which takes the modulated signal as input and outputs the original audio signal. Radio amateurs are the initial radio receivers. They had got drawbacks such as poor sensitivity and selectivity.Selectivity is the selection of a particular signal while rejecting the others. Sensitivity is the capacity of detecting RF signal and demodulating it, while at the lowest power level. Both Selectivity and Sensitivity should be high for an FM receiver. To overcome these drawbacks of the ordinary receiver, the superheterodyne receiver was invented. This FM receiver consists of 5 main stages.RF Tuner SectionThe modulated ... Read More

A Magic Tee junction is formed by attaching two simple waveguides one parallel and the other series, to a rectangular waveguide which already has two ports. This is also called an E-H Plane Tee junction or Hybrid or 3dB coupler.The arms of rectangular waveguides make two ports called collinear ports i.e., Port 1 and Port 2, while the Port 3 is called as H-Arm or Sum port or Parallel port. Port 4 is called as E-Arm or Difference port or Series port.The connections are made by the side arms to the bi-directional waveguide to form both the parallel and serial ... Read More

Rat-race junction is a microwave device used when there is a need to combine two signals with no phase difference and to avoid the signals that have a path difference.A normal three port Tee junction is taken and 4th port is added to it, to make this rat-race junction. All of these ports are connected in angular ring forms at equal intervals using series or parallel junctions.The mean circumference of total race be 1.5λ and that each of the four ports is separated by a distance of λ/4. The below figure shows the image of a Rat-race junction.Let us consider ... Read More

A Directional coupler is a device that samples a small amount of Microwave power for measurement purposes. The power measurements include incident power, reflected power, VSWR values etc. Directional coupler is used to couple the Microwave power which may be Uni-directional or bi-directional. It is a 4 port waveguide junction consisting of a Primary main waveguide and a Secondary auxiliary waveguide. The below figure shows the image of a directional coupler.PropertiesThe properties of an Ideal directional coupler are as follows.All the terminations are matched to the ports.When the power travels from port 1 to port 2, some portion of it ... Read More

A helical antenna is another type of wire antenna, which is widely used for a higher range of broadband VHF and UHF applications. The frequency range of operation of the helical antenna is around 30MHz to 3GHz.Helical antenna or helix antenna is the antenna in which the conducting wire is wound in a helical shape and connected to the ground plate with a feeder line. It is the simplest antenna which provides circularly polarized waves and used in extra-terrestrial communications in which satellite relays etc., are involved.It consists of a helix of thick copper wire or tubing wound in the ... Read More

To improve the radiation efficiency and directivity of the beam, the waveguide should be provided with an extended aperture so as to make the abrupt discontinuity of the wave into a gradual transformation, so that all the energy in the forward direction gets radiated. This can be termed as Flaring. Flaring is done to provide greater directivity and narrower beam width. The types of horn antennas depend on how they are flared.Sectoral HornThis type of horn antenna, flares out in only in one direction. Flaring in the direction of Electric vector produces the sectorial E-plane horn. As well, flaring in ... Read More

In Radio communication systems, we use wireless electromagnetic waves as the channel. The antennas of different specifications can be used for these purposes. The mode of propagation of electromagnetic waves in the atmosphere and in free space may be divided into the following three categories:The line of sight (LOS) propagationGround wave propagationSkywave propagationIn ELF (Extremely low frequency) and VLF (Very low frequency) frequency bands, the Earth, and the ionosphere act as a wave-guide for electromagnetic wave propagation. In these frequency ranges, communication signals practically propagate around the world. The channel bandwidths are small. Therefore, the information is transmitted through these ... Read More

Microstrip antennas are the low-profile antennas. A metal patch mounted on a ground level with a dielectric material in-between constitutes a Microstrip or Patch Antenna. These are very low size antennas having low radiation. The patch antennas are popular for low profile applications at frequencies above 100MHz.Construction and workingThe microstrip consists of a very thin metallic strip placed on a ground plane with a dielectric material in-between. The radiating element and feed lines are placed by the process of photo-etching on the dielectric material. Usually, the patch or microstrip is chosen to be square, circular or rectangular in shape for ... Read More

Babinet’s Principle is actually the principle used in optics. According to its definition, “When the field behind a screen with an opening is added to the field of a complementary structure, the sum is equal to the field when there is no screen”The images clearly explain the principle. In all the regions, which are non-collinear with the beam, the above two screens, in figure 1 & 2, produce the same diffraction pattern.Case1Consider a light source and a conducting plane (field) with an aperture before a screen. The light does not pass through the opaque area but passes through the aperture.Case2Consider ... Read More

The lens antenna uses a curved surface for the transmission or reception. Lens antennas are made up of glass, where the converging and diverging properties of the lens are followed. These are used for higher frequency applications greater at 3000 MHz and above.Working PrincipleIf a light source is assumed to be there at a focal point of a lens, which is at a focal distance from the lens, then the rays get through the lens as collimated or parallel rays on the plane wavefront.The rays that pass through the center of the lens are less refracted than the rays that ... Read More