Moving forward, beamforming will be an essential feature of base station antennas for next-generation wireless networks like 5G. Although beamforming has been around for decades, its primary uses have been for military radar jammers and satellite applications for achieving a highly directive and electrically steerable antenna beam. A steered beam has been often formed using a rotatable reflector antenna, which you commonly see in airport and marine radars or radio astronomy antennas.

Despite the disadvantages mechanically steered antennas have (like mechanical joints with limited life due to wear, fragile rotating RF joints to guide the transmitted/received energy to the radio, relatively slow re-steering times, and non-random access to specific pointing angles), electronic scanning arrays surmount these limitations by offering an antenna array with no moving parts that’s fixed in its position. In addition, the antenna pattern is steered electrically instead of mechanically.

Previous wireless generations didn’t have viable mechanically steered arrays due to the aforementioned limitations. Having said that, electrically steered arrays were considered impractical because of their required intense signal processing capabilities. As silicon densities and speeds have increased at significant rates over the past few decades, it’s easier to launch electrically steered beamforming in mobile networks and user equipment at a reasonable price point.

Looking toward future mobile communication networks, electrical beamforming is being considered an important feature to meet required data rates and network capacity, to achieve viable coverage using higher frequency bands within higher path losses, to better manage interference. Mobile network beamforming offers many advantages over sectored antenna patterns previously and currently applied in mobile wireless generations. Base stations broadcast the channel resources assigned for specific users within the full sector in these networks, meaning a very small percentage of power radiates in the direction of the intended user.

Another noteworthy benefit is the use of a directive antenna beam for reducing interference to other mobile users. This is done by minimizing radiation in directions, aside from the intended mobile user. This allows the same wireless spectral resources to be used for several links simultaneously within a sector for manageable interference levels. Generally, beamforming antenna is comprised of many individual antenna elements or sub-arrays, with each element connected to an individual transmitter or receiver channel. More arrayed elements generally result in higher gain and a narrower beam at its peak.

With each transmitted or received antenna signal, any one that is sent or obtained from some angles will add in-phase as the channels combine, while signals from other angles will subtract, thus cancelling out each other. In order to form peaks and nulls in the antenna beam, carrier frequency radiated by each array element, combined either constructively or destructively across numerous angles. If each channel’s delay is equal, the antenna beam’s peak will point directly perpendicular to the array, also known as the boresight angle. A progressive increase in electrical delay across the elements of the array will cause the antenna beam’s peak to be positioned at an angle that’s offset from boresight.

Carefully controlling the relative electrical delay through each transmitter or receiver path to each of the antenna elements can enable the beam to effectively be electrically steered across a wide angular range. The angle for each mobile user is determined and tracked to ensure the user received the strongest signal with minimum interference, when advanced acquisition and tracking algorithms are used. Due to advances in semiconductor process technologies, dozens of transmitter/receiver channels and many megaflops of processing capability have been implemented within considerably small and low power electrical components. This in turn, has brought the use of advantageous techniques (like beamforming) within reach of mobile wireless networks and low cost mobile devices to greatly enhance future network user’s mobile experience, along with addressing the continually increasing demands for wireless throughput and capacity.