Reliable data transmission from intelligent metering systems with the least possible installation effort - this was the challenge faced by Netze BW GmbH and the manufacturer Antennentechnik Bad Blankenburg GmbH (ATBB).
In just a few years' time, the business and network processes of the German energy industry will be based largely on the digital infrastructure of intelligent metering systems. Consumption and feed-in data from millions of connection points as well as a large number of control commands must be transmitted securely and in some cases at high clock rates. In many cases, (mobile) radio technology will be used for this purpose - today in the GSM or LTE network, later possibly also via 5G. The limitations of this technology are familiar to everyone from everyday life, explains Marco Schäfer, who is responsible at EnBW subsidiary Netze BW for the technical testing and qualification of communication technology in the environment of the intelligent metering system, among other things. "Certain structural environments and materials influence the propagation of radio waves," he explains.
Expert solution instead of standard technology
Exactly these conditions are often found where the smart meter gateways will soon be installed. "In concrete, underground rooms, behind steel fire doors or in close proximity to larger metallic objects, the signals are often disturbed," the expert explains. Added to this are differences in network coverage, which can impair data transmission, especially in rural areas. Such problems can only be reliably solved with antennas that are optimized for the existing conditions. After consultation with the mobile network operators, Netze BW decided early on to equip all smart meter gateways with antennas that support the bands for GPRS and LTE and are optimized for the LTE 800 MHz frequency band during rollout. According to the Netze BW expert, the best possible radio performance is required.
"Based on the experience gained from various laboratory and field tests, requirements were defined with regard to installation and radio characteristics. The antennas available on the market could not cover the requirements", remembers Marco Schäfer. The EnBW subsidiary therefore decided to work with ATBB, a specialized technology provider with a 100-year history of developing intelligent antenna systems for automotive, smart industry, secure government radio and smart meter applications for the energy sector and the appliance industry. "For more than 15 years, Netze BW - or its predecessor companies in the metering sector - has been working successfully with Antennentechnik Bad Blankenburg. ATBB has always convinced us in terms of innovation and quality," Schäfer sums up. For the rollout of Netze BW, the company not only supplies the already established DIN rail, station or outdoor antennas. In a joint development project, an innovative antenna solution was created that was optimized specifically with regard to the assembly processes.
Installation processes at a glance
In fact, the processes involved in installing the smart metering systems are absolutely critical in view of the expected quantity structures and the tight cost framework during rollout. "The communication connection of the gateway must therefore work right away," explains Marco Schäfer. Netze BW relies on standardized processes: "Before installation, a provider recommendation is automatically determined. At the customer's site, the installer then uses a level meter developed by Netze BW to check the local radio conditions and the installation location of the antenna. Ideally, the DIN rail antenna, which is plugged into the meter's module space, is sufficient to achieve the necessary signal strength. Otherwise, a special station or outdoor antenna must be mounted on the meter cabinet or in close proximity.
This procedure, according to the Netze BW expert, has a few pitfalls, however: "Of course, installation is more complicated and antennas outside the meter cabinet are also increasingly susceptible to mechanical damage. In particular, however, the network operator is dependent on the consent of the customer, who is the owner of the meter cabinet and the surrounding premises. "With a bricked-in meter cabinet, the installation of an antenna outside of the meter cabinet is not so simple," Schäfer knows from practical experience. For the reasons mentioned, it is in the interest of the metering point operator to install as many antennas as possible inside the meter cabinets.
Antenna built into the meter cabinet
Together with Antennentechnik Bad Blankenburg and the manufacturer Hager, Netze BW addressed this problem. "The vision was to develop an antenna that is more powerful than the DIN rail antenna and can be installed in the meter cabinet right away," reports ATBB Sales Manager Florian Rast. Particular challenges arise in this context with the numerous meter cabinets, which require special know-how in antenna installation due to the metal housing. "With the new development, we have actually succeeded in turning this weakness into a strength," explains Rast, "because the integrated antenna is designed in such a way that it specifically exploits these coupling effects of the surrounding metal in order to increase your antenna effective area. The control cabinet itself thus becomes an antenna and is able to radiate and absorb electromagnetic waves. "Due to the enlargement of the effective area by the cabinet, the result is an excellent efficiency and thus an optimal energy transport between cable and free space", adds Florian Rast.
In addition, the internal mounting protects the antenna from improper handling. The antenna, which supports mobile radio from 2G to 5G as well as CDMA 450, LoRaWAN 868 and WiFi/WLAN (2.4 GHz/5 GHz), is currently designed as standard for Hager meter cabinets with 19.7 x 8.1 cm cable entry fields. To keep installation as simple as possible, the antenna can simply be clicked into the housing of the switch cabinet. "This means there is no need to drill," emphasizes Florian Rast. At the same time, the antenna is protected in the best possible way. The connection to the gateway is made via the FAKRA socket. "We assume that the integrated antenna means that the installation of external antennas can be avoided in many cases". Marco Schäfer also sees great potential for the integrated antenna in the course of the upcoming rollout: "As expected, our initial tests have been very positive," he reports. At ATBB, the new product has now been included in the regular portfolio.
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