Antenna Calculator

Use Antenna Calculator to calculate total length of dipole,length of each dipole,Tee side, half tee side using frequency.

Antenna Calculator
Frequency
Total Length of Dipole: {{totalLengthResult() | number:4}}
Length of each dipole: {{dipoleLengthResult() | number:4}}
Tee Side: {{teeSideResult() | number:4}}
Half Tee Side (AF): {{halfTeeSideResult() | number:4}}

How to use Antenna Calculator?

Step 1 - Enter the Frequency

Step 2 - Calculate the Total length of Dipole

Step 3 - Calculate the Length of each Dipole

Step 4 - Calculate Tee side

Step 5 - Calculate Half Tee side (AF)

Antenna Calculation Formula:

l = 468 / f

e = l / 2

t = e / 2

h = t / 2

Where,

l = Total Length of Dipole

f = Frequency

e = Length of Each Dipole

t = Length of Tee Side

h = Length of Half Tee Side

Frequently Asked Questions

What is the relationship between antenna frequency and physical size?

Antenna size is inversely proportional to frequency. A half-wave dipole at 1 MHz is about 150 m long, while at 1 GHz it’s only 15 cm. The formula l = 468/f (with f in MHz, l in feet) directly relates frequency to optimum antenna length. This relationship is fundamental to antenna design - higher frequencies allow smaller antennas, which is why mobile phones use compact antennas while AM radio stations need large tower arrays.

Why is dipole length optimized to half-wavelength at resonance?

The half-wavelength dipole has several advantages: it’s resonant (purely resistive input impedance), efficient radiation (maximum power from given current), and well-understood pattern. At resonance, the input impedance is approximately 73Ω (real part), allowing efficient matching to 50Ω transmission lines with a simple matching network. Operating at non-resonant lengths requires impedance matching or results in reduced efficiency.

How do I use this calculator to design an antenna for a specific frequency?

Enter your operating frequency in MHz or GHz, and the calculator provides the optimum dipole dimensions. Total length gives the full antenna size. Length of each dipole is half of that. The Tee side and half Tee side parameters describe the dimensions of a Tee antenna configuration used in some applications. These dimensions are starting points - fine-tuning may be needed based on nearby objects and desired impedance match.

What are practical limitations when building antennas at very low or very high frequencies?

At very low frequencies (LF/MF), antennas become impractically large (hundreds of meters). Solutions include shortening the antenna with loading coils or using non-resonant designs. At very high frequencies (mm-wave), antennas become very small and demanding in fabrication precision. Mechanical stability and environmental protection become important. Frequency choice often represents a trade-off between antenna size and other system requirements.

How does antenna resonance affect radiation efficiency and impedance matching?

Resonant antennas (like λ/2 dipoles) present purely resistive impedance, simplifying matching and maximizing radiation efficiency. Off-resonant antennas require tuning (adding capacitance or inductance) for impedance matching. Mismatched antennas have reduced transmit power delivery and receive sensitivity. Understanding resonance is essential for antenna design and network analysis.

Physical Basis & References

This calculator applies Resonant Half-Wave Dipole Design:

$$\text{Total Length} = \frac{468}{f_{MHz}} \text{ (feet)} = \frac{142.65}{f_{GHz}} \text{ (meters)}$$

Key Physics Principles:

  • Wave Equation - Wavelength = speed of light / frequency
  • Resonance - Half-wavelength dipole exhibits standing wave pattern
  • Radiation Efficiency - Maximum at resonance with purely resistive input impedance
  • Matching Theory - Resonant impedance simplifies network integration

Key Assumptions:

  • Thin wire dipole in free space
  • Dipole located far from ground and other objects
  • Operating at fundamental resonance
  • Sinusoidal current time dependence
  • Far-field observation region

Typical Range of Values:

  • Frequency: 1 MHz to 40 GHz
  • Antenna length: 7.5 meters (40 m band) to 3.75 mm (10 GHz)
  • Input impedance: ~73Ω at resonance
  • Directivity: 2.15 dBi (omnidirectional)

Further Reading:

  • Balanis, C.A. (2016). Antenna Theory: Analysis and Design, 4th Edition. Wiley.
  • ARRL Antenna Book - American Radio Relay League
  • Electromagnetic Wave Propagation - MIT OpenCourseWare

Conclusion

You can read more about Antenna Array factor calculator and Antenna Gain Calculator on below links

Read more about other Physics Calculator on below links