Chair: Roland Gabriel and Matthias Geissler

Within this workshop the expert group ‘Antennas’ presents active and steerable antennas for mobile communications and navigation. The workshop comprises the basic technology and the modelling of steerable antennas, some state-of-the-art examples for different applications as well as recent advances and specific technology improvements. The workshop is subdivided into five talks, each of them contains a presentation of the topic followed by an interactive discussion.

08:40 – 09:20

Designing steerable antenna arrays using simulation

Susanne Hipp, OTH Regensburg, Faculty for Electrical Engineering and Information Technology, Seyboldstraße 2, 93053 Regensburg, Germany

Antenna arrays are one possibility to design a steerable antenna. Designing an antenna array is a challenging task, where simulation can help to reduce the design complexity. Simulating a complete array can be computational expensive, therefore designing the array is often broken in several task. The first goal is to design and optimize a single antenna element followed by an optimization of this antenna element while considering the vicinity of further equal elements. A unit cell approach is a feasible and easy way to accomplish this task. This approach already considers parameter such as active element pattern and radiation pattern angles. As soon as the unit cell optimization, emulating an infinite array, is finished, the real array with a finite size is simulated, especially considering edge elements and parameters such as excitation patterns or active and passive elements. Due to the high simulation effort at this stage optimization should be kept to a minimum and high performance computing might be required. Finally, a feeding network and different excitations for various beam patterns can be investigated using combined methods to reduce the simulation effort.

09:20 – 10:00

Active Distributed Antenna Solutions in indoor and outdoor environment

Roland Gabriel, Ericsson Antenna GmbH Germany, Klepperstr. 26, 82000 Rosenheim

To achieve the requested throughput in the mobile communication network of the 5G, multiple MIMO and beamsteering technologies are the relevant focus technologies. However, in order to support the requested services in indoor buildings as well as in public buildings or places, often a high numbers of different standards have to be supported in parallel. Therefore distributed antenna systems, based on fronthaul interfaces as well as synchronized multistandard pico and femto basestations  are the best approach. To adjust the antenna coverage and beam, steerable mechanisms for coverage and interference interference control are required. Small active steerable antennas are considered as alternative approach for enhanced coverage of public places. Millimeter wave solutions can also serve as data hot spots as well as bridges or repeaters for the requested high speed and low latency fronthaul or backhaul. In this contribution basic concepts for multistandard distributed antenna systems based on backhaul and fronthaul interfaces are compared and mmW repeater implementation is discussed.

Coffee Break

10:20 – 11:00

Circular Switched Parasitic Array Antennas

Thomas Bertuch, Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR, Fraunhoferstraße 20, 53343 Wachtberg, Germany

The conventional technological approach for electronic beam scanning uses array antennas, electronically tunable phase shifters and RF distribution or beam forming networks. This has several drawbacks like high manufacturing costs, high design and manufacturing complexity and typically a limited field of view. Tunable antennas represent a cost effective alternative. Circular switched parasitic array (CSPA) antennas  are a special class of reactively controlled antennas with two-dimensional omnidirectional beam switching capabilities. The field radiated by a single active antenna element is influenced by tuning the loads of several nearby parasitically coupled passive antenna elements. The loads of the coupled antenna elements can be either continuously tunable or switchable in discrete steps. A circular distribution of parasitic antenna elements around a central active element facilitates the switching of a directive beam over 360° in the antenna plane. The shape of the radiation pattern cut in the direction perpendicular to the scanning plane is typically fixed but can be adjusted during the design process.

11:00 – 11:30

Nullsteering and Beamforming for Robust Satellite Navigation

Stefano Caizzone and Achim Dreher, German Aerospace Center (DLR), Oberpfaffenhofen, 82234 Wessling

Satellite navigation has nowadays become an enabling technology in very different application fields, ranging from aeronautics to bank transactions, from shipping to autonomous driving. Due to the increasing dependency from satellite navigation, also the need for robust systems, able to counteract unintentional or intentional interferences, is expanding. Robustness implies, however, the need for more complexity, with top performance being obtained through the use of multi-antenna receivers capable of performing spatial nulling in the direction of the interference(s) as well as beamforming in the direction of the satellites, for improved signal-to-noise ratio. Steerable antennas assume then an important role in the achievable performance: the miniaturization of such antenna arrays and their capability to suppress unwanted signals while achieving good sky coverage for desired signals are currently the main challenges. Different antenna arrays will be shown during the talk, with different grades of miniaturization and performance, for use in mobile applications (aircraft, drones, …) as well as in static scenarios (e.g. reference stations).

11:30 – 12:00

Concepts for steerable arrays in 5G communications at Millimeterwaves

Matthias Geissler,  IMST GmbH, Carl-Friedrich-Gaußstr. 2-4, 47475 Kamp-Lintfort

Wireless mobile communication systems at MM-waves are capable of extremely high data rates (high bandwidths). A prerequisite for this are highly-directional antennas, mainly for fixed access points and fronthaul and backhaul services. Depending on the application and on the scenario, agile antenna frontends are an excellent solution, enabling beamsteering and multibeam functionality. The antenna concepts and technology can differ, depending on the services required: some concepts are well suited for multibeam coverage, others are optimised for small cell applications. This paper presents several concepts for different scenarios.