Leaky Wave Antennas
In 2003 TNO developed, together with Satimo and Saab-Ericsson Space, a new type of ‘leaking wave’ (leaky-wave) antenna for ESA-ESTEC. The antenna design is based on the principle that as a wave propagates along the interface between two different dielectric media, it travels with a phase constant which is roughly the average of the ones associated with each of the homogeneous media separately. The phase constant thus occurs as a slow wave for the less dense medium and a fast wave (leaky) for the denser medium. If the two media are free space and a dense dielectric, radiation occurs in the dielectric. This type of propagation does not involve multiple reflections due to a finite thickness slab, or to a waveguide type of cross-section. Therefore, a well-designed antenna is characterised by a constant beam direction over a very wide frequency range.
In the innovative design, the antenna radiation comes from a milled slot on the interface between air and a dense dielectric. The antenna shape is a cylinder of elliptical cross-sections with decreasing dimensions of four layers of glued ceramic and a layer with a copper layer with a specific dielectric constant (manufactured by Rogers). The dual-band antenna centered its transmissions around 10.5 and 22.5 GHz. The making of the antenna was a technical tour de force. Some steps in the production process are shown below:
This leaky lens antenna (LLA) has prompted the further development of more types of LLAs for special purposes, including an Ultra-WideBand (UWB) antenna operating between 3.1 and 10.6 GHz.
Since 2010, further developments of this type of antennas takes place at the Technical University of Delft.
Neto, A., Maci, S., de Maagt, P.J.L. (1998). Reflections inside an elliptical dielectric lens antenna. IEEE Proc.-Microw. Antennas Propag., Vol. 145, No. 3, June 1998. DOI: dx.doi.org/10.1049/ip-map:19981884
S. Maci and A. Neto, “Green’s Function of an Infinite Slot Printed Between Two Homogeneous Dieletrics—Part II: Uniform Asymptotic Solution“, in IEEE Transactions on Antennas and Propagation, vol. 52, no. 3, pp. 666-676, March 2004.
Neto, A., Bruni, S., Gerini, G., & Sabbadini, M. (2005). The leaky lens: a broad-band, fixed-beam leaky-wave antenna. IEEE Transactions on Antennas and Propagation, 53(10), 3240-3246. DOI: 10.1109/TAP.2005.856351
S. Bruni, A. Neto and F. Marliani, “Phase Center Stable Ultra Wide-Band Antenna for EMC Field Sensing“, 2006 European Microwave Conference, Manchester, 2006, pp. 1625-1628. DOI: 10.1109/EUMC.2006.281412
S. Bruni, A. Neto and F. Marliani, “The Ultrawideband Leaky Lens Antenna in IEEE Transactions on Antennas and Propagation, vol. 55, no. 10, pp. 2642-2653, Oct. 2007. https://ieeexplore.ieee.org/document/4339556
Bruni, S., Neto, A., Gerini, G., & Bekers, D. J. (2007). Leaky lens antenna for multi-beam imaging systems. In Proceedings of the European Radar Conference, 2007, Munich, 10-12 Oct. 2007 (pp. 111-113). Piscataway: Institute of Electrical and Electronics Engineers. DOI: doi.org/10.1109/EURAD.2007.4404949