Workplan › Work Package 3

WP3: Q-band Low profile high gain antenna

Leader Participants
THALES TCF, ONERA, Fraunhofer, ORTEH

The main target of this work package is to provide low-profile high-gain Q-band antennas fulfilling the demanding requirements for base stations of future backhaul and capillary access communication network.

To this end, we will study the possibilities that can bring sub-wavelength structures and engineered materials. Two different approaches will be developed in parallel:one relying on high gain lens antenna; the other one on Fabry-Perot cavity antenna. This will allows testing and assessing various approaches while assuring a risk reduction to ensure the best performances achievement.

The best performing and cost effective antenna developed in this work package will be then used for platform integration (WP6) and field trials (WP7).

Lens antenna

Current lens antenna technology can be either bulky for refractive design or inefficient when it comes to low-profile solution (such as Fresnel lens). The optimization and use of both diffractive lens as well as appropriated lens feeder could greatly help in improving the overall antenna efficiency, a key issue in the Q-band. Different materials for lens substrate have been investigated and low-cost solutions are foreseen for mass production. During the project an innovative lens design with a sub-wavelength (sub-λ) structure, which allows the lens efficiency to be improved while obtaining high gain (i.e. > 32dBi) in a low-profile design has been designed and manufactured. With this antenna, the lens thickness is reduced by more than a factor of 3 compared to the bulk configuration and a 2.5-dB gain improvement at 42 GHz with respect to the classical solution based on Fresnel lens is obtained. An example of such sub-wavelength radome integrated lenses for the NTE node is presented in Figure 1.

Radome lenses

Figure 1. Fabricated radome lenses for the NTE node

Fabry-Perot antenna

Concerning the Fabry-Perot antenna, the simplicity of the feed mechanism makes the antenna attractive for the SARABAND project. Such kind of antenna can be realized by placing a RF source between a partially reflective surface (PRS) and a totally reflective surface (TRS). For a practical design, a trade-off must be found between maximum directivity and pattern bandwidth. For Q-band application, it appears that an air filled cavity with a printed substrate Partially Reflective Surface, and a Perfect Electric Conductor as the Totally Reflective Surface offers the most promising performances and a limited cost.

In particular, the Fabry-Perot antenna designed and fabricated in SARABAND is comprised of periodic patches printed on a thin dielectric slab (PRS), and a patch in an air cavity, which is used as the excitation source for the FP cavity. The patch in air cavity is fed through a coupling slot which is excited by a 50 Ohm microstrip line located underneath the antenna. Figure 2 shows the Q-band Fabry-Perot antenna prototype, which presents a directive beam pattern in the broadside direction with a gain of 15 dBi at 43.10 GHz. Further work is in progress to increase the antenna gain by using multiple sources inside the cavity.

Antenna prototype

Figure 2. Fabry-Perot antenna prototype