Antenna dB Gain Calculator

Antenna Gain Formula:

\[ \text{Gain (dB)} = 10 \times \log_{10}(\text{Efficiency} \times \text{Directivity}) \]

Antenna Gain:

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1. What is Antenna dB Gain?

Antenna gain is a performance measure that combines the antenna's directivity and electrical efficiency. It represents how well the antenna converts input power into radio waves in a specific direction compared to an isotropic antenna (which radiates equally in all directions).

2. How Does the Calculator Work?

The calculator uses the antenna gain formula:

\[ \text{Gain (dB)} = 10 \times \log_{10}(\text{Efficiency} \times \text{Directivity}) \]

Where:

\( \text{Efficiency} \) — Ratio of radiated power to input power (0 to 1)
\( \text{Directivity} \) — Measure of how 'focused' the radiation is compared to isotropic
\( \log_{10} \) — Base-10 logarithm

Explanation: The formula converts the product of efficiency and directivity to decibels (dB), which is a logarithmic scale commonly used in antenna measurements.

3. Importance of Antenna Gain Calculation

Details: Antenna gain is crucial for designing communication systems, determining coverage areas, and optimizing signal strength in specific directions. Higher gain antennas provide more focused radiation patterns.

4. Using the Calculator

Tips: Enter efficiency as a value between 0 and 1 (where 1 represents 100% efficiency). Directivity should be greater than 1 (typically between 1.5 and 20 for common antennas).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between gain and directivity?
A: Directivity measures the antenna's ability to focus radiation in a direction, while gain includes both directivity and efficiency (power losses).

Q2: What are typical gain values for common antennas?
A: Dipole antennas: ~2.15 dBi, Yagi antennas: 8-15 dBi, Parabolic dishes: 20-30 dBi, Isotropic: 0 dBi by definition.

Q3: Why use decibels (dB) for gain?
A: The logarithmic dB scale conveniently represents large variations in power ratios and makes multiplication of gains into simple addition.

Q4: What's the difference between dBi and dBd?
A: dBi is gain relative to isotropic, while dBd is relative to a dipole (0 dBd = 2.15 dBi).

Q5: Can efficiency be greater than 1?
A: No, efficiency is always ≤1 (100%) as it represents what fraction of input power is actually radiated.