Carlos A. Fernandes (IT-Lisboa)
José R. Pereira (IT-Aveiro)
Custódio O. Peixeiro (IT-Lisboa)
António A. Moreira (IT-Lisboa)
Jorge R. Costa (IT-Lisboa)
Carlos Salema (IT-Lisboa)
The antenna activity at IT covers a wide range of topics spanning from very low frequencies up to mm- and sub-mm waves, for very different applications, although with especial focus on mobile communication applications and on space applications. The main IT antenna expertise is located at Lisbon and at Aveiro, and is backed by measurement capability up to 110 GHz, and prototype manufacturing up to 60 GHz.
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The work has been focused mainly on dielectric antennas and namely on shaped dielectric antennas. A new concept was introduced in 1992 with shaped lenses with integrated feed for constant-flux illumination of highly shaped regions for advanced mobile broadband communication systems at 40 GHz and 60 GHz bands. This work was developed under EU funded projects, and the prototypes were used in the test-bed demonstrators.
Work on lenses evolved subsequently for planar lenses using artificial dielectrics and recently for double material integrated shaped lenses, seeking high efficiency, ultra-wideband, good scanning characteristics at mm-waves and sub-mm waves. The latter wok is being developed under an ESA-ESTEC contract and, besides the concept validation prototypes, it involves the development of a lens design and optimization tool – ILASH.
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More on "MM wave antennas"
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Book Chapters
- Fernandes, C. A.; "Shaped-Beam Antennas" - Chapter in Handbook of Antennas in Wireless Communications, Lal Godara, CRC Press, New York, 2002.
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The work has been focused on small printed antennas mainly for handset and laptop applications. Several types of single and multi-element multi-band and wideband patch antennas have been designed, fabricated and tested.
PIFA and PIFA-like elements have been developed for application in multi-standard handsets with emphasis in miniaturisation techniques and multi-band or wideband performance.
A new concept of printed antenna – the omnidirectional wrapped patch antenna (OWMA) – has been recently introduced. It consists of a patch wrapped around the ground plane edge. This configuration provides almost omnidirectional radiation and is particularly adequate for integration around laptop screen edges. Multi-element arrangements of OWMAs can provide increased MIMO capacity.
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Papers in Journals
- J. Guterman; Y. Rahmat-Samii; Moreira, A. A.; Peixeiro, C.;
"Quasi-Omnidirectional Dual-Band Back-to-Back E-shaped Patch Antenna for Laptop Applications", Electronics Letters, Vol. 42, No. 15, pp. 845 - 847, July,2006.
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| More on "Small printed antennas" |
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Work is focused on near-field ultra-low-cost UHF RFID antennas for tag reading in self-confined interrogation volumes like shelves, or conveyor belts, without the need for portics, shields or barriers. Recent work has followed in the direction of short-range RFID localization.
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| More on "RFID antennas" |
Papers in Journals
- Medeiros, C. R.; Costa, J.R.; Fernandes, C. A.;
"RFID Reader Antennas For Tag Detection in Self-Confined Volumes at UHF", IEEE Antennas and Propagation Magazine, Vol. 53, No. 2, pp. 39 - 50, April,2011.
Abstract | Full text (PDF 4446KB)
- Medeiros, C. R.; Costa, J.R.; Fernandes, C. A.;
"RFID Smart Shelf with Confined Detection Volume at UHF", IEEE Antennas and Wireless Propagation Letters, Vol. 7, No. --, pp. 773 - 776, October,2008.
Abstract | Full text (PDF 963KB)
Papers in Conference Proceedings
- Medeiros, C. R.; Costa, J.R.; Fernandes, C. A.;
"UHF RFID Smart Conveyor Belt with Confined Detection Range", Proc IEEE AP-S/URSI International Symp., Charleston, SC, United States, Vol. -, pp. - - -, June, 2009.
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Work under this topic addresses the design and characterization of antennas with reconfigurable geometry by electronic switching. Used switching elements are either PIN diodes or MEMS, and the antennas are designed for frequency agility or for beam agility.
One of the focus of the research is on the influence of the switch packaging, further to the RF switch characteristics. This may be especially relevant for an accurate prediction of antenna performance when encapsulated MEMS are used.
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| More on "Reconfigurable antenas" |
Papers in Conference Proceedings
- Medeiros, C. R.; Costa, J.R.; Fernandes, C. A.; Kolundzija; "Modelling of a MEMS Reconfigurable Antenna Using WIPL-D", Proc ESA Antenna Workshop on Multiple Beam and Reconfigurable Antennas , Noordwijk, Netherlands, Vol. 1, pp. 369 - 372, April, 2007.
Abstract | Full text (PDF 215KB)
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