Hello Experts!
What is meaning of Antenna gain in wireless devices in the sense that antenna is actually a passive device without any external power?
Anything between 1dBi and 17 dBi.
Not concerned with values.
Just trying to understand how antenna can amplify signal without any external power supply?
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That gain is not terms of power.
Generally an antenna is omni directional, but whenever you make it directional it shows gain since 1 major lobe is formed and rest lobes gets reduced.
In this sense we are calling it as gain.
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Okโฆ directional gain.
Thanks for clarifying. 
Gain in terms of an isotropic antenna, unit dBi.
Antenna does not amplify signal.
It is just that in some directions of space signal will sum up from multiple antenna elements adding it cumulative.constructively to a high signal whereas in other directions signals from different antenna elements will act destructively will not add up.
Kepp in mind that an antenna can have multiple elements (dipole usually).
Ok. In an omni directional antenna, antenna gain would be almost 0 dB, right?
Nope.
Isotropic has 0.
Omni still has some gains in some directions.
Try google it to find pattern of omni antenna.
Omnidirectional Atenna Radiation Pattern
Why Antenna have Gain while itโs Passive component?
Have you ever wondered why we talk about โgainโ when referring to antennas, even though they are passive components?
Letโs explore the fascinating concept behind antenna gain and shed light on it.
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Antennas are essential elements in wireless communication, Microwave Transmission, satellite systems, radar technology, and so on. Antennas have ability to efficiently radiate electromagnetic energy.
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โGainโ is a term used to describe an antennaโs ability to concentrate or direct its radiated power in a specific direction. It measures the antennaโs efficiency in utilizing available power and focusing it towards a desired target or receiver.
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But wait, arenโt antennas passive components that do not actively amplify power? Absolutely! The gain of an antenna is achieved by effectively utilizing the available power and directing it in a specific direction, rather than actively amplifying it.
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The gain of an antenna is typically measured in decibels (dB) and is often referenced to an isotropic radiator or a reference antenna. An isotropic radiator is a theoretical antenna that radiates power equally in all directions, serving as a benchmark for comparing the directional properties of real antennas.
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Dish antennas that used in Microwave Transmission utilize a parabolic reflector to focus the electromagnetic energy in a narrow beam, resulting in increased signal strength and longer communication range
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. Stop Stop โฆ Why larger dish antennas are associated with higher gain? So easy,The larger the diameter of a dish antenna, the larger the surface area available for capturing or radiating electromagnetic energy. This concentration of energy results in a narrower beamwidth and higher gain.
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So, the next time you hear about โgainโ concerning antennas, remember that it signifies their ability to effectively direct or concentrate radiated power in a desired direction.
LinkedIn: 
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What Makes a High-Gain Antenna Actually High-Performance?
High gain sounds great but in practice, itโs often misunderstood. A high-gain antenna doesnโt automatically mean high performance. The real value lies in how that gain is achieved, where itโs radiated, and what is sacrificed to get there.
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Gain vs Directivity vs Efficiency:
Gain (G) is a product of an antennaโs directivity (D) and efficiency (ฮท):
Gain = Directivity ร Efficiency
High directivity with low efficiency (due to mismatch, material losses, or surface waves) can still produce โhigh gainโ on paper but the actual radiated power may be far below ideal. -
Front-to-Back Ratio and Side Lobes:
Many antennas achieve high gain by narrowing the main lobe, but this often results in high side lobes or poor front-to-back ratio (FBR). In practical systems, these degrade:
- Beam purity
- Signal-to-noise ratio (due to interference pickup)
- Physical layer security (due to unwanted radiation leakage)
A truly high-performance antenna should exhibit high gain with low sidelobe level (SLL) and high FBR, especially in beamforming and directive systems.
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Aperture Efficiency and Effective Area:
For aperture antennas, gain is linked to the effective aperture area (A_eff) and wavelength (ฮป):
Gain = (4 ร ฯ ร A_eff) / (ฮป2)
However, aperture efficiency (ratio of A_eff to physical aperture) must be optimized. Poor feed design, edge diffraction, or phase errors reduce A_eff which means high physical size but subpar actual gain. -
Phase Distribution and Amplitude Tapering:
In array antennas, gain depends on maintaining a coherent phase front across elements. Amplitude tapering (used to reduce side lobes) lowers gain unless carefully optimized. Misalignment, mutual coupling, and feed delay variations lead to beam squint, pattern distortion, and effective gain loss in desired directions. -
Gain Bandwidth Product (GBP):
High gain often comes at the cost of bandwidth. For narrowband applications (e.g., radar), this is acceptable. But in wideband/multiband systems, gain flatness across bandwidth is critical. The gain-bandwidth product becomes a more meaningful figure of merit than gain alone. -
Real-World Metrics: Embedded Efficiency & Environment Sensitivity:
Antennas embedded in platforms (smartphones, wearables, vehicles) experience detuning and pattern distortion due to material loading and user interaction. A โ10 dBiโ antenna in simulation might radiate far less in deployment.
High-performance antennas should maintain gain while tolerating detuning, multi-path effects, and near-field obstructions.
A high-gain antenna is only valuable if it delivers stable, directional, and efficient radiation under real-world conditions.
LinkedIn:
So if beamwidth increases, does gain also increase?
No, antenna gain and beamwidth have an inverse relationship.
If beamwidth increases, gain decreases, and if beamwidth decreases, gain increases.
- Antenna gain is a measure of how effectively an antenna directs energy in a specific direction.
- Beamwidth refers to the angular spread over which the antenna radiates power.
A narrow beam (small beamwidth) concentrates energy in one direction, increasing gain. A wide beam (large beamwidth) spreads energy over a larger area, reducing gain.
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Exactly, antenna gain refers to its capability to focus energy in a particular direction.