An RF antenna radiation pattern shows how the antenna distributes energy in different directions. Before comparing two patterns, confirm that they use the same frequency, coordinate reference, polarization, gain type, and test setup. Without this information, two similar-looking curves may describe very different antenna conditions.
What a Radiation Pattern Can Tell You
A radiation pattern helps identify where an antenna radiates strongly, where the response becomes weaker, and how the coverage changes around the antenna. It can show the main beam direction, broad coverage areas, deep nulls, and unwanted secondary lobes.
For a broader comparison of coverage shape, see our guide to omnidirectional and directional antennas.
The pattern does not represent communication distance. Link range still depends on the connected radio, RF path loss, interference, obstacles, and the antenna at the other end of the link. A curve can reveal a weak direction, but it cannot tell you the exact distance available in that direction.
Frequency also matters. A multiband antenna may have a balanced pattern at one frequency and a tilted or irregular pattern at another.
3D Patterns and 2D Cuts
A 3D radiation pattern shows the antenna response around the full spatial volume. It gives a clearer view of upward radiation, downward radiation, beam tilt, and weak regions that may be hidden in a single flat plot. Each plot is a cut through the 3D pattern, so it represents one selected plane instead of the complete coverage shape.
A smooth 2D curve does not prove that the antenna has no nulls in other directions. When equipment orientation changes during use, the 3D result or several 2D cuts provide a more complete view.
Reading Azimuth and Elevation
The azimuth pattern normally shows radiation around a horizontal reference plane. It is often used to check how evenly an antenna covers the area around a device.
For an external antenna mounted vertically on an industrial gateway, a balanced azimuth pattern may support communication around the installation point. It does not show whether the signal becomes weak directly above or below the antenna.
The elevation pattern shows radiation through a vertical reference plane. It helps reveal upper and lower coverage, vertical beamwidth, beam tilt, and nulls that do not appear in the azimuth plot.
The antenna drawing beside the pattern is part of the technical result. It shows how the product was positioned and which physical direction corresponds to zero degrees. Without this reference, the peak direction cannot be mapped reliably to the top, bottom, front, or side of the equipment.
Reading Lobes, Beamwidth, and Nulls
Start with the strongest part of the curve. Its direction marks the main lobe, which shows where the antenna has its highest response in the selected plane.
For a fixed point-to-point link, the main beam needs to face the target device. For equipment that can rotate or change orientation, a single narrow peak may be less useful than a broader and more balanced pattern.
The 3 dB beamwidth is measured between the two angles where the main lobe falls 3 dB below its peak. A narrow beam concentrates energy into a smaller angle, while a wider beam covers a broader angular area.
Beamwidth needs to be checked in both azimuth and elevation. An antenna may have broad horizontal coverage but a much narrower vertical beam.After reading the main beam, look for deep drops in the curve. These nulls can create weak communication directions even when the reported peak gain appears suitable.
Confirm the Scale and Gain Type
In a normalized pattern, the highest point is normally set to 0 dB. The rest of the curve shows how far each direction falls below that peak. The 0 dB mark in this plot does not mean the antenna gain is 0 dBi.
Normalized patterns are suitable for checking beam shape, balance, null depth, and side-lobe distribution. They do not show which antenna has higher absolute gain unless comparable peak-gain data is provided separately.
An absolute plot may show directivity, gain, or realized gain. Check which quantity is used before comparing curve values. Two plots using different gain definitions are not directly comparable.
For related gain, realized gain, VSWR, and pattern checks, see our RF antenna testing guide.
The radial scale also changes how the curve looks. A plot with 5 dB divisions may appear smoother than a plot with 2 dB divisions, even when the measured variation is similar. Check the scale interval and the minimum displayed level before judging null depth or pattern balance.
Match the Frequency and Test Setup
Antenna pattern shape changes across frequency. The main beam may tilt, the beamwidth may change, and new nulls or side lobes may appear near the edge of an operating band.
For a wideband or multiband antenna, review representative plots near the lower, middle, and upper parts of each required band. Two antennas need to be compared at the same or closely matched frequency points.
Installation conditions can significantly change the measured pattern. PCB dimensions, ground plane, antenna clearance, battery, display, shielding, housing material, and nearby metal can alter the current distribution and coverage shape.
FAQ
Conclusion
An RF antenna radiation pattern becomes useful when its frequency, plane, scale, polarization, and test setup are clear. Read the azimuth and elevation cuts together, then check the main beam, beamwidth, nulls, and secondary lobes against the intended equipment position. For antenna comparison, use data measured under matching conditions and give more weight to the final PCB, housing, cable route, and mounting arrangement. If you are evaluating an RF antenna for a wireless device, you can share the target frequency band, installation drawing, antenna position, cable type, connector requirement, and available pattern data with the Bafitop team for review.