What Are Beamforming Antennas and How Are They Tested?

What Are Beamforming Antennas and How Are They Tested?

Beamforming antennas are used to power and enhance technologies like Wi-Fi and 5G, so users can have more precise connections and increased data speeds. Beamforming is typically used in conjunction with MU-MIMO technology. As progressing technology requires faster data rates and higher densities of mobile equipment, antenna technology needs to be updated as well, which is what beamforming is used for. 

Keep reading to learn more about beamforming antennas and how they are tested.

What Are Beamforming Antennas?

Beamforming, as explained by Electronics-Notes, is “the basic formation of a beam of energy from a set of phased arrays. Using phased antenna arrays it is possible to control the shape and direction of the signal beam from multiple antennas based on the antenna spacing and the phase of the signal from each antenna element in the array.”

Unlike broadcast antennas, which spread their signal in multiple directions, beamforming focuses a signal toward a specific receiving device. This produces a direct, faster, and more stable connection. Frequencies for these antennas are fairly high, usually around the 2-5 GHz region or higher.

But what is the purpose of a beamforming antenna? Electromagnetic waves naturally radiate signals in all directions from a typical antenna unless they are blocked or, in the case of beamforming, shaped and directed. To stop the signal from radiating in multiple directions and specifically focus it, multiple antennas in close proximity will broadcast the same signal at varying times. The result is that these electromagnetic waves overlap, producing interference that either strengthens or weakens the signal. This allows these radiated waves to be used as effectively as possible.

Testing Beamforming Antennas

Beamforming antennas radiate electromagnetic waves to wirelessly power Wi-Fi and 5G devices, which means that they need to prove compliance. This testing can be done in a variety of different ways, including passive antenna testing, active antenna testing, and near field-far field (NF-FF) transformation.

Passive Antenna Testing 

This form of testing uses over-the-air, or OTA testing to measure the RF signal of a test signal fed to the antenna array. The device under test (DUT) is usually a passive antenna ray that does not have an active radio unit. This testing provides simple and easy-to-compare results. Passive antenna testing usually involves measuring characteristics including gain, directivity, efficiency, side lobe ratios, and more. 

Active Antenna Testing

Active antennas have antenna ports embedded in the device. Because of this, the process of generating RF signals is performed within the device itself. Thus, testing must be performed when the device is active so the DUT will actively signal and the radio unit and antenna array operate as they would in the real world. Integration between the radio unit and active antenna array is very close, which requires that more parameters be measured than in a traditional conducted test setup.

The typical parameters measured depend on the frequency range. On the FR1 range, these parameters include the transmitted power and sensitivity of the base station. On FR2, parameters include transmitted power, the sensitivity of the base station, and all RF parameters like EVM, ACRL, blocking, selectivity, and spurious emissions need to be evaluated over the air.

Near Field-Far Field Transformation

In near field-far field (NF-FF) transformation, the near field radiation pattern can be converted to measure the far field radiation pattern using modal expansion of the spatial field distribution. The appropriate modal expansion is chosen depending on the antenna being tested. 

NF-FF transformation is used to measure the far field radiation pattern of large antennas, like base stations, point-to-point antennas, and antenna arrays for space applications and radar sensing. When used to measure space and radar applications, near field measurements are taken. Then a far-field radiation pattern is created using NF-FF techniques. 

The NF-FF approach reduces the distance necessary to measure far field characteristics, so antennas can be measured in smaller chambers without losing accuracy.

Get RF Testing Help at RF Exposure Lab

Testing beamforming antennas introduces new challenges to RF testing for various reasons, like increased integration between the radio unit and antenna, and larger antennas that require far field testing capability.

When you’re in need of RF testing for a project, come to the experts here at RF Exposure Lab. The importance of working with an experienced, A2LA accredited testing lab cannot be overstated. Working with an experienced RF testing lab as early as possible in the design process will help you successfully get through the maze of regulations and ensure that your product is compliant.

We offer RF exposure testing services for a variety of wireless devices, such as

As well as many more devices! If you’re looking for RF exposure testing help that is provided with expertise, speed, accuracy, and integrity, contact us to learn more about our services or to get a quote.