Sector Antenna Calculator
Calculate sector antenna gain, wavelength and directivity using beamwidth and efficiency.
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Inputs
Live
Math
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Related
Enter parameters and click Calculate to view results
Formula & Theory
Gain(dBi)=10log10((41253 × η)/(HPBW × VPBW))This formula is used to calculate antenna parameters for sector antenna calculator.
Overview
This sector antenna calculator estimates gain and directivity from the horizontal and vertical half-power beamwidths (HPBW/VPBW) using the standard beamwidth approximation — a fast way to size panel antennas for cellular sectors, point-to-multipoint WISP links, and Wi-Fi sector coverage without running a full pattern simulation.
Input Guide
Enter Frequency, Horizontal Beamwidth, Vertical Beamwidth, Efficiency exactly in the units shown by this sector antenna. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Frequency — use MHz.
- Horizontal Beamwidth — use °.
- Vertical Beamwidth — use °.
- Efficiency — use %.
Output Guide
The results describe the calculated sector antenna values for the inputs you entered. Check each value against the available space, selected components, feed system, and operating conditions before making a final design decision.
How This Calculator Works
The Sector Antenna uses Gain(dBi)=10log10((41253 × η)/(HPBW × VPBW)). Supply Frequency (MHz), Horizontal Beamwidth (°), Vertical Beamwidth (°), Efficiency (%) in the displayed units, then use the calculated values as the first engineering target for this specific antenna types design or analysis.
Design Notes
Sector antennas trade gain for coverage angle: a 65° azimuth panel used in 3-sector cellular deployments typically yields 14–18 dBi, while a wider 90° or 120° sector antenna drops to roughly 10–14 dBi for the same aperture efficiency, because the beamwidth-product formula shows gain scaling inversely with HPBW × VPBW. This is the fundamental trade in sectorized coverage — narrower sectors mean more cells and more backhaul, but every sector radiates with more gain and correspondingly better link budget per sector. The efficiency input (η) absorbs real-world losses that this simplified beamwidth formula doesn't model directly: aperture illumination taper, sidelobe leakage, and ohmic losses in the feed network. Typical well-designed sector panels run 55–70% efficiency; values above 75% are unusual outside of highly optimized designs, so treat a high efficiency entry as a flag to double-check your assumptions.
Build and Tuning Notes
This beamwidth-approximation formula (41253/(HPBW×VPBW)) assumes a reasonably well-behaved, single main-lobe pattern with roughly symmetric sidelobes — it becomes less accurate for antennas with heavy beam-shaping (e.g. electrically down-tilted panels with asymmetric elevation patterns, or antennas with deliberately shaped nulls for interference control). For those cases, treat the calculator's gain figure as a first-pass estimate and confirm against the manufacturer's datasheet or a full 3D pattern integration before finalizing a link budget. Also remember that directivity and gain differ only by efficiency here — directivity ignores ohmic and mismatch losses entirely, so it represents the theoretical ceiling for a lossless aperture of the same beamwidths, while gain is what the antenna will actually deliver into free space.
Frequently Asked Questions
Why does narrowing the beamwidth increase gain?
Antenna gain and beamwidth are inversely related for a fixed radiated power: concentrating energy into a narrower beam increases the power density in that direction at the expense of coverage elsewhere. This is why 65° cellular sector panels have noticeably higher gain than 120° sector panels of similar size and construction.
What is a typical efficiency value for a sector antenna?
Most commercial sector panel antennas achieve 55–70% aperture efficiency once feed network losses, sidelobe leakage, and illumination taper are accounted for. Efficiency above roughly 75% is uncommon in practice and usually indicates either an idealized assumption or a highly specialized design.
What is the difference between gain and directivity?
Directivity describes how tightly an antenna concentrates radiation in its favored direction assuming no internal losses — it depends only on the radiation pattern shape. Gain applies the antenna's real-world efficiency to directivity, accounting for ohmic losses, impedance mismatch, and other dissipative effects, so gain is always equal to or less than directivity.
How accurate is the beamwidth-product gain formula?
The 41253/(HPBW×VPBW) approximation is accurate to within roughly 1 dB for well-behaved antennas with moderate sidelobes and beamwidths under about 90°, which covers most practical sector and panel antennas. It becomes less reliable for very wide-beamwidth antennas, heavily shaped patterns, or antennas with significant backlobe radiation, where a full pattern integration gives a more trustworthy result.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.