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Dipole Antenna Calculator

To use Dipole Antenna Calculator, enter the values of required input fields and hit the calculate button

Formula:
Current (I) = Im Sin (β(L - |z|) )
Im
L
λ
r
z
θ

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Dipole Antenna Calculator

Enter the required values in the designated fields to find the current passing through a dipole antenna. 

The dipole antenna calculator tells you other parameters as well like Electric and Magnetic waves and Average radiated power density

How to use this calculator? 

The directions to use the dipole antenna calculator are given below.

  1. Enter the following parameters.
  • Maximum current (Im)
  • Total dipole length (L)
  • Coordinate angle (θ)
  • Z-axis length (point along the antenna where you want to determine the current)
  • Radius (r) of the dipole wire or rod
  1. Click calculate. 

What is a dipole antenna?

A dipole antenna is a simple and widely used type of radio antenna that is essentially a straight electrical conductor measuring half a wavelength long. 

It is typically divided in the middle by an insulating gap where the feed line is connected. When radiofrequency current is applied, it radiates radio waves into the surrounding space.

The simplest form of dipole antenna is the half-wave dipole, in which each of the two-rod elements is one-quarter of a wavelength long. This design produces an omnidirectional radiation pattern in the plane perpendicular to the antenna, with zero radiation along the antenna's axis.

Dipole antenna formula:

The current distribution along a dipole, especially a half-wave dipole, can be described by the following formula:

Current (I) = Im Sin (β(L - |z|) )

Where:

  • Im is the maximum current.
  • L is the total length of the dipole.
  • β is the phase constant or propagation constant of the wave, given by 2π/λ, with λ being the wavelength.
  • z represents the distance from the center of the dipole, and ∣z∣ ensures that the absolute value of this distance is considered, given the symmetric nature of the current distribution.

However, this calculator requires more detailed parameters for a nuanced analysis:

  • Coordinate Angle (θ): Specifies the position from which you're evaluating the antenna's radiation characteristics. This angle is crucial in determining the radiation pattern and field strength of the antenna at a particular orientation.
  • Z-axis Length: Refers to the position along the antenna's length (from its center) where you want to calculate the current.
  • Radius (r): Represents the physical radius of the conducting wire or rod of the dipole. A thicker antenna (with a larger radius) generally has wider operational bandwidth.

By incorporating parameters like the coordinate angle, z-axis length, and antenna radius, this calculator captures the antenna's three-dimensional spatial orientation, enhancing its precision and reflecting real-world conditions more accurately.

How to find the current of the dipole antenna?

The formula above calculates the current at a designated distance z from the antenna's center, factoring in the total length L of the antenna and the phase constant β. 

While this formula provides a basic current distribution, it's essential to recognize that the radius r of the dipole can influence its overall performance and impedance.

Another vital parameter is the coordinate angle θ. This angle offers an observational perspective of the antenna's radiation. 

Solved Example:

Let's illustrate the process to calculate current with a numerical example:

Step 1: Start by listing the given parameters:

Maximum current (Im) = 3A

Frequency: 300 MHz (which gives β = 2π×300×106/ 3 × 108=2π)

Total length L of the dipole: 1m

Distance z from the center: 0.25m

Coordinate angle θ: 45°

Radius r of the dipole: 0.005m (5mm)

Step 2: With the given values, compute the current distribution using the formula:

Current (I) = Im Sin (β(L - |z|) )

Plugging in the values, you get:

I=3Asin(2π(1−0.25))

I=3Asin(1.5π)

The sine of 1.5π is -1, so the result becomes:

I=−3A

Step 3: Interpret the result.

The negative sign indicates the current's direction has reversed compared to the center of the dipole. Hence, at 0.25m from the center, the current magnitude is 3A, flowing in the opposite direction.

Daily applications:

Dipole antennas, owing to their simplicity and efficiency, have found a broad range of applications in daily life. Here are some of the everyday applications of dipole antennas:

FM Radio: The telescoping antennas on many FM radios are half-wave dipoles. When you extend the antenna on an FM radio, you're effectively using a dipole to receive broadcast signals.

Television Antennas: Many of the traditional rooftop TV antennas are variations of the dipole antenna, designed to capture VHF (Very High Frequency) and UHF (Ultra High Frequency) television signals.

Wi-Fi Routers: Most Wi-Fi routers and access points have built-in dipole antennas. They can be internal or external whip antennas.

Ham Radio: Amateur radio operators often use dipole antennas because they're relatively easy to build and offer good performance for both transmitting and receiving.

Mobile Phones: The antennas in older mobile phones, especially those protruding ones, are a form of dipole antennas.

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