The SPINNER Cluster Connector:
A Housing That Grows with Your Requirements
Antennas and base stations for mobile communications are shrinking and new transmission technologies are constantly appearing. As a result of these trends, connections of many different kinds are already needed, including coaxial, fiber-optic, DC, AISG etc. To help get all this under control, SPINNER has developed a new concept that bundles connectors in an array: the SPINNER Cluster Connector, which accepts connections of virtually any type to facilitate the use of widely differing technologies on the same antenna.
From the Idea to the Serial Production
Interview with SPINNER Product Manager Reiner Berchtold
This article explains the potential of this new approach for reducing risks for your infrastructure while increasing its efficiency. The Cluster Connector is now almost ready for mass production, having already undergone a whole evolution since we first came up with the idea back in 2014. In the following interview, Reiner Berchtold―one of our top experts―tells the story of how the first prototype took shape.
Mr. Berchtold , where did the idea for the Cluster Connector come from?
It all started when we developed the 4.3-10 system. These connectors were the first to have spring-loaded contacts, which ensured excellent values even with low tightening torque. Our developers then realized that the same approach could be used to create a whole cluster of connectors.
When was the idea first put into practice?
In 2014, in our R&D center in Feldkirchen-Westerham southeast of Munich. A customer had asked us to directly connect a radio unit to an antenna, in other words without jumpers. We brainstormed and came up with a sketch of a system in which the radio was directly attached to the antenna with a connector cluster in between. Our idea was to use a kind of cluster to join all the different RF connections between the radio and the antenna.
That sounds like you were getting ready to build a prototype.
That’s right―we then built a prototype that simulated the connection between the radio and antenna for testing it under field conditions. We made two sheet-metal boxes as proxies and hooked them up using a proto-cluster that our technicians built. Then we joined the boxes and performed tests to see how well it worked.
How well did the prototype work?
Very well. We got excellent RF values right from the start, similar to those we obtained while developing the 4.3-10 connector system. The intermodulation levels were especially convincing.
How sensitive to vibration and motion was the connection?
That’s an important point, because antennas can move around a lot when there is strong wind. And a mobile communication base station needs to work reliably even at hurricane wind speeds up to 200 kilometers an hour. So we simulated rough environmental conditions by hitting it with our hands and even a hammer. We documented this test in a video, and you can see how robust the connection already was: the test curve didn’t even budge.
Why didn’t you develop the system any further?
We naturally kept working on it, but didn’t put on the market yet because the radio unit turned out to be too heavy to attach to the top of the antenna. But we continued to improve the system and adapt it to new market requirements. The miniaturization trend was just starting to really take off, which worked in our favor. That’s why we are now ready to offer a system that’s able to meet both current and future needs.
You have certainly set yourself ambitious goals. How do you intend to meet future market requirements as well?
The system is based on a platform philosophy. In other words, we have created a platform that is inherently flexible and therefore has great potential for continuing to evolve. Our eyes are on the future. This is the only way for us to meet the needs of the communication market, which is changing at an accelerating pace.
Can you give us some examples of details that you improved?
In the proto-cluster, the sockets on the antenna were floating and the plugs fixed. We reversed that configuration. As a result, now there are female connectors on the antenna and floating male connectors in the cluster. This lets the individual cables rotate, which is useful during installation, among other things for making sure that jumpers with angled connectors are correctly aligned.
These days, antennas can have up to 20, 24 or even 30 connections. Where is this trend heading?
More and more systems are being packed into antennas. Lots of scenarios are imaginable. Active antennas, for example, which are going to take off with the spread of 5G networks, require a data interface that can use fiber-optic cables. Things like this have kept us racking our brains to come up with more ways to improve the cluster. But we’ve stayed with the basic idea because it delivers huge benefits.
How Clusters Improve Efficiency
The Cluster Connector has a plastic housing, because we know from experience that metal contacts can be more susceptible to intermodulation. What’s more, a plastic housing prevents corrosion of all kinds, which completely eliminates the risk of individual connectors or the entire cluster getting jammed.
The plastic plate opposite the cluster can be integrated one-to-one in the antenna base. This means that afterward it is only necessary to install the electronical contacts. So antenna manufacturers can integrate the housing without any additional costs. This approach also improves the stability of the antenna base. There is no need for a large aperture to accommodate the entire cluster―nine small holes are enough.
With conventional systems, it’s necessary to individually install nine jumpers, which takes nearly two minutes. The SPINNER Cluster Connector is plugged in and locked in seconds, slashing the required installation time by at least 90%!
What’s more, it delivers an excellent compromise between the insertion force and the number of connections. Nine jumpers can be installed at once without fussing with multiple cables.
Reduced Infrastructural Risks
The Cluster Connector works like a container and grows to embrace new technologies. Currently the following interfaces are planned: 2.2-5, 1.5-3.5, NEX10 as RF interface, DC, AISG and fiber optics.
Looking ahead, virtually any number of additional interfaces can be added to the Cluster Connector. They only need to be an appropriate size and meet certain minimum mechanical requirements. This means that you can flexibly choose the number of connections and which technologies you want to include. The magical thing about the Cluster Connector is that it can accommodate a vast range of different technologies.
Today it’s already normal for antenna installations to support up to seven different bands and have a corresponding number of base stations. From there, sometimes as many as 60 cables can lead to three antennas. These numbers greatly increase the risk of incorrectly joined connectors.
The Cluster Connector bundles the connections to eliminate the danger of confusion at the site. The installer simply plugs in the entire cluster, inside which all of the connectors are already correctly aligned.
In October 2018 we submitted the Cluster Connector to NGMN for recommendation as a future industry standard. Our initiative there is supported by Amphenol, Kathrein and Telegärtner.