E-Band radios, operating in the 71-76/81-86 GHz frequency range, have become the dominant wireless technology for demanding multi-gigabit per second transport applications in mobile and fixed networks. Due to their superior TCO structure, when compared to optical fiber deployments and other lower frequency microwave (MW) radio link alternatives, E-Band radios are the preferred wireless option to provide Backhaul services to 5G/5G Advanced systems, while the next generation of E-Band systems is planned to be the foundation of wireless 6G network transport.

Hundreds of thousands of E-Band radios have already been deployed around the world, predominantly for transport links of short and medium range up to about 5 km with link availabilities of 4 9s or better. Nevertheless, long range E-Band radio links have also been deployed in many cases for longer links, up to 10 km and beyond, albeit with smaller link availabilities. Communication Service Providers (CSPs) are keen on extending the ranges for which E-Band links are applicable so that they can exploit the capacity and cost advantages of E-Band technology for longer, high availability wireless backhaul links.

One of the ways to achieve this objective is to increase the nominal diameter of the used E-Band antennas from a maximum of 60 cm (2 feet), which has been the norm so far, to 90 cm (3 feet) or even more.

Challenges of large diameter E-Band antenna deployment

A particular characteristic of E-Band antennas is that, even for a relatively small nominal diameter of 60 cm, they feature a very high gain of around 50 dB, and the beamwidth of their main radiation lobe at half of their maximum gain (Full Width Half Maximum — FWHM) is quite narrow at around 0.5 degrees. A nominal 90 cm diameter E-Band antenna features a beamwidth FWHM of around 0.3 degrees. For comparison, a 15 GHz antenna with a nominal diameter of 60 cm has a FWHM of around 2.5 degrees.

The small value of antenna beam FWHM imposes special attention during the phase of link alignment but also has important implications in the alignment stability of E-Band links during operation. There are several types of antenna support structures, such as self-supporting towers, guyed masts, and pole/mast mounts on rooftops, some of which are more susceptible to deformation/instability effects than others. Deformations may still cause a measurable effect on an E-Band link's alignment and performance by deflecting the very narrow E-Band antenna main radiation lobe even by few tenths of a degree.

It has been observed that in some cases, the radio/antenna mounting structure can exhibit a small tilting/bending deformation, which may vary throughout the day under the influence of direct solar radiation. This tilting/bending effect is caused by differential thermal expansion of different parts of the pole/tower structure. In other cases, under the influence of strong wind, it is possible for weaker antenna mounting structures to start swaying in both the elevation and azimuth planes, causing a twist of the antenna beam and detrimental effects on link SNR and performance.

Such effects have, so far, restricted the size of deployed E-Band antennas to a maximum of 60 cm, thus influencing the useful range of E-Band links. A solution is to introduce an antenna design that can actively respond to the discussed link alignment deviations to restore the link alignment to as close an optimized state as possible.

The INTRACOM TELECOM/FAINI 2-D E-Band beam stabilization antenna

Since 2016 Intracom Telecom has been designing, developing, and manufacturing high RF performance E-Band radios, featuring market leading spectral efficiency and range. Furthermore, Intracom Telecom's antenna manufacturer subsidiary Faini Telecommunication Systems designs and manufactures high performance MW, E-Band and Dual Band antennas. Responding to CSP's requirements for longer and more stable E-Band-based multi-gigabit per second links, Intracom Telecom and Faini proceeded to the co-development of an E-Band Automatic Beam Stabilizing Antenna (ABSA).

The E-Band ABSA system has been designed to provide antenna beam stabilization in two-dimensions (2-D), i.e. in both the Elevation and Azimuth planes, and is applicable to both 60 cm and 90 cm nominal diameter antennas. A unique feature of the Intracom Telecom/Faini 2-D ABSA is that it has been designed from the start to be a Dual Band antenna that is capable of combining E-Band and MW radios through a single dish.

The E-Band ABSA system is composed of a control module placed in an outdoor enclosure externally attached to the antenna mount, and a specially designed configurable subreflector/dipole mechanism integrated inside the antenna reflector drum. The beam compensation mechanism processes sensor data from embedded high accuracy accelerometers and gyroscopes. These detect movements and deviations of the radio/antenna system from an initial reference orientation and provide input to an algorithm that controls the adjustment of the antenna active sub-reflector positioning. The Intracom Telecom ABSA system also receives feedback from the RSL indication of the attached radio to calibrate and optimize the stabilization efficiency, accuracy, and reliability.

Conclusion

The use of the Intracom Telecom ABSA system improves the average link capacity and link availability when the antenna installation structure suffers from thermal expansion/contraction related tilting. The Intracom Telecom ABSA enables the more widespread deployment of 90 cm diameter antennas, enhancing the link gain by about 5 dB compared to 60 cm diameter antennas, contributing to the possible extension of the range of high availability E-Band multi-Gbit/s radio links by up to 20%.

The, currently unique, Dual Band capability of the Intracom Telecom ABSA system can enhance the range extension benefit derived from the use of 90 cm diameter antennas by multiplying it with the range extension benefit of the Dual Band technique. Combining this innovative antenna with Intracom Telecom's long range UltraLink™ E-Band radios enables CSPs to deploy E-Band technology in their networks for significantly larger than before link ranges.