Table of Contents
What happens inside an antenna?
The antenna at the transmitter generates the radio wave. A voltage at the desired frequency is applied to the antenna. At the receiver, the electromagnetic wave passing over the antenna induces a small voltage. Thus, the antenna becomes the signal source for the receiver input.
What are the necessary condition of radiation of an antenna?
There are basically 3 conditions that have to be met in order for these antennas to radiate effectively: The antenna must have two parts; both parts must not be electrically small; something must induce a voltage between the 2 parts.
What is the first condition to make radiation from an antenna?
The current in each part of the antenna flows in the same direction. Such current is called antenna mode current. This condition is special because it results in radiation. As the signal applied to the two halves of the antenna oscillates, the field keeps reversing and sends out waves into space.
Do receiving antennas emit radiation?
A receiving antenna performs the reverse of the process performed by the transmission antenna. It receives radiofrequency radiation and converts it into electric currents in an electric circuit connected to the antenna.
What is meant by radiation pattern of an antenna?
The radiation pattern or antenna pattern is the graphical representation of the radiation properties of the antenna as a function of space. That is, the antenna’s pattern describes how the antenna radiates energy out into space (or how it receives energy).
What is needed for radiation?
Radiation is energy given off by matter in the form of rays or high-speed particles. All matter is composed of atoms. In that process, unstable nuclei may emit a quantity of energy, and this spontaneous emission is what we call radiation.
What is antenna radiation?
In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern) refers to the directional (angular) dependence of the strength of the radio waves from the antenna or other source. Other software, like HFSS can also compute the near field.
Why radiation is important for an antenna?
Abstract. The radiation pattern of an antenna is one of its basic properties since it shows the way the antenna distributes its energy in space. It generally consists of a number of lobes and if it is measured far away from the antenna it is independent of distance.
What are antennas made of?
Copper is a best suited material for base antennas. The metal, while soft and malleable, is quite rigid. Stainless steel has a higher tensile strength, so thinner wire can be used….Why build antennas out of copper and not aluminum or stainless steel.
| Metal | Conductivity |
|---|---|
| Silver | 106 |
| Copper (pure) | 100 |
| Copper (hard Drawn) | 89.5 |
| Aluminum | 45 |
How is radiation pattern of antenna determined?
- Measurement of Radiation Pattern:
- 2/λ from the antenna where λ is the wavelength.
- E-plane: The E-plane is the plane passing through the antenna in the direction of beam maximum and parallel to the far-field E vector.
- Experimental Procedure:
- 2/λ, where.
What is FM receiver?
A radio or FM receiver is an electronic device that receives radio waves and converts the information carried by them to a usable form. An antenna is used to catch the desired frequency waves. Frequency modulation is widely used for FM radio broadcasting.
Where does the energy from antenna radiation come from?
In fact, the antenna radiation process just occurred as a consequence of EM wave generation. Once created, the EM wave antenna radiation is self-sustaining and independently contains all the energy which it received at the time of its formation within its electric and magnetic field components.
How does the energy of an EM wave affect an antenna?
Once created, the EM wave antenna radiation is self-sustaining and independently contains all the energy which it received at the time of its formation within its electric and magnetic field components. Therefore, any form of loading on the propagating EM wave by receiving antennas do not cause any counter-effect on the transmitting antenna.
How is the radiation from an antenna cancelled?
Hence, the radiation from one wire is cancelled by the current flowing in the adjacent wire (that is travelling the opposite direction). Another question that will arise is – if its so simple, then everything could be an antenna.
How does the current pass through an antenna?
The antenna is a terminal of electric current; there is no current passing through an antenna, only the voltage oscillates with the input current. This oscillating voltage in the transmitter antenna induces an alternating current in the air, propagating away from the surface of the antenna at a 90-degree angle,…