# How do radio antennas work physics?

How does an antenna work? The antenna at the transmitter generates the radio wave. A voltage at the desired frequency is applied to the antenna. The voltage across the antenna elements and the current through them create the electric and magnetic waves, respectively.

## How does a dipole antenna work?

A dipole antenna commonly consists of two identical conductive elements such as metal wires or rods. The driving current from the transmitter is applied, or for receiving antennas the output signal to the receiver is taken, between the two halves of the antenna.

## What does a dipole antenna need to radiate electromagnetic waves?

Dipole antenna basics The name ‘di-pole’ indicates that the dipole antenna consists of two poles or items – two conductive elements. Current flows in these two conductive elements and the current and the associated voltage causes an electromagnetic wave or radio signal to be radiated outwards from the antenna.

## How does an antenna generate radio waves?

1) Electricity flowing into the transmitter antenna makes electrons vibrate up and down it, producing radio waves. 2) The radio waves travel through the air at the speed of light. 3) When the waves arrive at the receiver antenna, they make electrons vibrate inside it.

## What is an antenna physics?

An antenna is a transducer; that is, a device which converts signals in one form into another form. In the case of an antenna, these two forms are (1) conductor-bound voltage and current signals and (2) electromagnetic waves. Traditional passive antennas are capable of this conversion in either direction.

## How does current flow in a dipole antenna?

The charge and current on the dipole create fields that are perpendicular to each other. The electric field, E, flows from the positive charge to the negative charge placed on the elements by voltage applied to the antenna as shown in Figure 3(a).

## Why it is called dipole antenna?

A ‘dipole’ means ‘two poles’ hence the dipole antenna consists of two identical conductive elements such as rods or metal wires. The length of the metal wires is approximately half of the maximum wavelength (i.e., ) in free space at the frequency of operation.

## What are the advantages of dipole antenna?

Dipole antennas offer the advantage of receiving balanced signals. The two-pole design enables the device to receive signals from a variety of frequencies. It also helps the device sort out problems caused by conflicting signals without losing reception quality.

## What is the polarization of dipole antenna?

Further, the E-field only has one vector component and consequently the fields are linearly polarized. When viewed in the x-y plane (for a dipole oriented along the z-axis), the E-field is in the -y direction, and consequently the dipole antenna is vertically polarized.

## How efficient is a dipole antenna?

The antenna efficiency of a λ / 8 long dipole antenna is 89.159%.

## What is a FM dipole antenna?

Dipole Antennas Include: One area in which dipole antennas are often used is for the reception of VHF FM broadcasts. Many Hi-Fi tuners and other radios have input sockets that will accept the input from a coaxial feeder, and where no external antenna is used, a dipole antenna can provide an excellent solution.

## What is the best antenna for FM radio?

• TERK Omni-Directional Indoor FM Antenna.
• TERK Amplified AM/FM Stereo Indoor Antenna.
• Bingfu 75 Ohm FM Antenna.
• Bingfu Magnetic Base FM Radio Antenna.
• Ancable FM Antenna for Indoor Stereo Receiver.
• Shakespeare FM Antenna.
• Dectan Indoor FM Antenna.

## How can I make a simple FM antenna?

A radio wave is generated by a transmitter and then detected by a receiver. An antenna allows a radio transmitter to send energy into space and a receiver to pick up energy from space. Transmitters and receivers are typically designed to operate over a limited range of frequencies.

## How does antenna radiate electromagnetic energy?

Instead of a loudspeaker, an antenna converts electrical energy (from the modulator) represented by movement of charge carriers in a conductor to electric and magnetic fields (electromagnetic energy). These travel through the air as a radio wave.

## Which type of antennas are used by the radio waves for transmission?

Yagi antenna – consists of an active antenna and a number of passive antennas, serving as directors or reflectors. This type of antenna is used mainly for transmission and reception of FM radio and TV broadcasting.

## What is basic antenna theory?

A transmitting antenna is one, which converts electrical signals into electromagnetic waves and radiates them. A receiving antenna is one, which converts electromagnetic waves from the received beam into electrical signals. In two-way communication, the same antenna can be used for both transmission and reception.

## How do you increase dipole antenna gain?

In order to increase the gain of an antenna, you need to concentrate its effectiveness in the required direction. Two common methods are to concentrate horizontal beamwidth by adding reflectors and directors, thus creating a Yagi beam.

## What is meant by radiation pattern of an antenna?

The radiation pattern is defined as a mathematical function or a graphical representation of the far field (ie, for r≫2D2/λ, with D being the largest dimension of the antenna) radiation properties of the antenna, as a function of the direction of departure of the electromagnetic (EM) wave.

## What direction does a dipole radiate?

The radiation pattern polar diagram for a half wave dipole antenna shows that the direction of maximum radiation or sensitivity is at right angles to the axis of the RF antenna. The radiation falls to zero along the axis of the RF antenna as might be expected.

## What wire is used for dipole antenna?

Perhaps the most common wire used in antennas is copper ‘building’ wire. This is PVC plastic coated wire, seven strand, 2.5mm. It is the sort of product that most low-current electrical switchboards use. It is reasonably inexpensive and moderately tough.

## Is a dipole balanced or unbalanced?

A balanced antenna is symmetrical about the feed point (e.g. a dipole) whereas an unbalanced antenna is not systematical about the feed point (e.g. a Windom).

## How does an antenna generate current?

In reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified.