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Calculators / Antenna Aperture
Antenna Effective
Aperture Calculator
Calculate the effective aperture Ae of any antenna using the fundamental RF engineering formula Ae = λ² G / (4π). Also solves for gain from aperture, computes aperture efficiency, and compares physical vs effective capture area. Essential for RF link budget and antenna selection.
Effective Aperture (Ae)
Physical Aperture (A)
⚙ Effective Aperture Engine
λ = — cm
0 dBi = isotropic. Dipole = 2.15 dBi
Physical cross-section of the antenna
Used when solving for G from Ae
Advanced Parameters
Uniform illumination=1.0, typical dish=0.55–0.70
Ohmic loss reduces effective aperture. % (100=lossless)
Reduces effective Ae by polarisation mismatch factor
W/m²
Pr = Pd × Ae (received power at antenna terminal)
Calculated Results
Effective Aperture (Ae)
—cm²
Aperture efficiency (Ae / A)
— %
Ae (m²)—
Ae (cm²)—
Gain (dBi)—
Gain (linear)—
Wavelength (λ)—
λ² / (4π)—
Physical Aperture (A)—
Aperture efficiency (ηap)—
Received Power (Pr)—
Gain (dBd)—
Enter values above to calculate.
📖 Theory
Every antenna — regardless of its physical size or type — has an effective aperture Ae: the equivalent capture area that intercepts incoming power from a plane wave.
Core Formula
Ae = λ² G / (4π)
λ = free-space wavelength, G = linear gain
Received Power
Pr = Pd × Ae
Pd = incident power density (W/m²). This is the Friis equation in aperture form.
Aperture Efficiency
ηap = Ae / A
A = physical aperture area. ηap < 1 always. Uniform illumination → ηap = 1 (max). Typical dish ≈ 0.55–0.70.
Key Insight
An isotropic antenna (G=1, 0 dBi) has Ae = λ²/4π. A dipole (2.15 dBi) has Ae = 0.13λ². A 30 dBi dish at 10 GHz has Ae ≈ 0.24 m² despite a physical size of ~0.4 m². That is aperture efficiency.
📡 Aperture vs Gain Viewer
Live Simulation
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◉ Ae scales with gain and frequency
Chart Type
Gain
10 dBi
−540 dBi
Frequency
2.4 GHz
0.1 GHz30 GHz
Ae vs Gain
ℹ
RF Engineer Insights
Enter antenna gain and frequency to see effective aperture insights.
Common Applications
RF Link Budgets
Received power Pr = Pd × Ae. Effective aperture connects antenna gain directly to received power in any link budget calculation.
Satellite Earth Stations
Compare effective aperture of dish antennas for uplink/downlink. Larger Ae → more received power from the satellite.
Radar System Design
Radar range equation uses transmit gain and receive effective aperture. Larger Ae improves target detection sensitivity.
Antenna Comparison
Compare a small patch (low Ae) vs a dish (high Ae) at the same frequency. Ae reveals the true capture capability of any antenna.
Get "10 RF Design Principles Every Engineer Should Know" Free
Learn practical principles for better RF circuits, PCB layouts, simulations, measurements, and troubleshooting.