Development of Self-Recoverable Antenna Systems
[Copyright 2008-2015.   Miroslav Joler]




Present State of the Art

Antennas are used for a large number of applications such as TV broadcasting (terrestrial and satellite), mobile telephony, target tracking, remote sensing, transportation, to mention a few.

In the present state of the art, there are:

"Classical" antenna systems (e.g. TV towers)

- they do not change their radiation characteristics during operation

KVMD-DT (Los Angeles)
  - elevation of over 8,000 feet above sea level, is subject to significant show fall and heavy icing conditions
  - operates on Ch23, serving over 8 million viewers


Smart antennas

- they execute the algorithm stored in their circuitry (switched-beam / adaptive-beam)

to probe further: F. Rayal, "Why have smart antennas not yet gained traction with wireless network operators?," IEEE AP Magazine, vol. 47, 6, pp. 124--126, Dec. 2005

Switched Beam Array






















switched beam array
[image source: Nallatech]

Adaptive Beam Array


















adaptive beam array
[image source: Nallatech]

























They are meant to have a fixed beam shape, which is steerable [left figure] or they have adaptive beam forming [right figure], in order to direct their radiation on the desired target and avoid interferers.

Recent advances in antennas: reconfigurable antennas

check some pertinent papers listed below:

1. S. Jung, M. Lee, G.P. Li, and F. de Flaviis, IEEE Trans. AP, 54, pp. 455--463, Feb. 2006.
2. L.M. Feldner, C.T. Rodenbeck, C.G. Christodoulou, and N. Kinzie, IEEE Trans. AP, 55, pp. 3310--3319, Nov. 2007.
3. D.E. Anagnostou, G. Zheng, M.T. Chryssomallis, J.C. Lyke, G.E. Ponchak, J. Papapolymerou, and C.G. Christodoulou, IEEE Trans. AP, 54, pp. 422--432, Feb. 2006.
4. S. Zhang, G.H. Huff, L. Feng, and J.T. Bernhard, IEEE Trans. AP, 52, pp. 2773--2776, Oct. 2004.
5. H. Aissat et al., IEEE Trans. MTT, 54, pp. 2856--2863, June 2006.

"Reconfigurable antennas" are meant to reconfigure themselves in terms of some parameters such as the radiation pattern, polarization, or operating frequency. Early works focused on reconfiguration of (only) one parameter. Naturally, later works had proposed reconfiguration of more than one parameter.


Challenge

Whatever the approach, current solutions are based on the premise that all elements of the antenna array are fully operational. However, if any element of the system fails, the original characteristics of the system will degrade, possibly severely. The user is then affected by that situation until the problem is fixed, which can bear loss of service and high costs, especially for spaced-based systems. Let's see some examples of pattern degradation due to element failure (by the "element failure" we don't just mean the sole failure of an antenna, but a failure along the path to the antenna (e.g. in the cable or in the splitter) that prevents the antenna to deliver the radiation according to the original design):

Example 1.
  • let the array from the figure above comprise 4 dipoles and a radiation pattern as shown in the figure below

  • let's observe the same pattern from the side and the top: 2 main lobes and nulls between them

All array elements working properly - side view


All array elements working properly - top view























Now, if array element #3 fails (dipole arms disappear in the upper figure), the pattern gets deformed, as shown in the figures below:
  • besides 2 original lobes, 2 parasitic lobes are created as the result of element failure

  • 2 parasitic lobes eventually radiate in the directions they are not meant to and create interference to other systems, or, simply, waste part of the input power

Second array element failed - side view


Second array element failed - top view




















Example 2.


A more detailed quantitative measure of array radiation degradation can be observed by 1D plot, as shown next.
  • the original (1111) has 1 main lobe and 2 suppressed back lobes

  • failure of element #3 (1101) causes back lobes to become major radiation, while formerly a major lobe is now suppressed

  • failure of element #4 (1110) here produces wider major lobe of the original level and (only) 1 back lobe of a level higher than before



This is a small, 4-element array, with a simple radiation pattern and small number of possible failure combinations (e.g. 1101, 1110, and 1010) that lead to pattern degradation. The point was to demonstrate the principle of pattern degradation and imply how serious this can be in case of large arrays and/or more subtle beam shapes.


So, the question is: How do we efficiently recover the system if part of it fails...
... on a hard-to-reach location, or
... at a critical moment?


Objectives

  • Our objective here is to develop a solution which will enable antenna system to recover itself if failure of any element occurs. This new kind of antenna we refer to as self-recovering or self-adaptive antenna system.

  • We plan to do a seamless integration of real-time computing and system optimization utilizing advanced hardware and software.

  • If success, this could be a predecessor to a broad range of future self-adaptive components, module, and systems.

  • The solution will bring improved reliability and versatility to systems and substantial cost-savings.

While the antenna system is meant to operate autonomously, the user will retain control over the system by means of monitoring and remote control. In the extension of this solution, we would be able to adapt the system not only when something fails, but also to attain new characteristics even when everything is healthy.

This solution will be significant for all systems where it is sought to have intelligent operation and immediate response of an antenna system to a sudden failure or to a change of conditions in the surrounding environment. Such situations can readily appear in the critical fields of today's technology, such as broadcasting, transportation, defense, security, and the emerging field of telemedicine.


Publications within the Project

  1. M. Joler, “Self-Recoverable Antenna Arrays,” IET Microwaves, Antennas & Propagation, vol. 6, no. 14, pp. 1608-1615, 2012.
  2. M. Joler, “How FPGAs can Help Create Self-Recoverable Antenna Arrays,” International Journal of Antennas and Propagation, vol. 2012, Article ID 196925, 10 pages, 2012.
  3. M. Joler, D. Malnar, and S.E. Barbin, “Real-Time Performance Considerations of an FPGA-Embedded Genetic Algorithm for a Self-Recovery of an Antenna Array,” 2010 ICECom, 20th International Conference on Applied Electromagnetics and Communications, Dubrovnik, Croatia, 20-23 September, 2010, Proceedings CD.
  4. M. Joler, D. Malnar, and S.E. Barbin, “An FPGA-enhanced genetic algorithm for mitigation of a flawed array radiation,” 2010 ICEAA, International Conference on Electromagnetics in Advanced Applications, Sydney, Australia, 20-24 September, 2010, pp. 616-619.
  5. D. Malnar, M. Joler, C.G. Christodoulou, “Embedding an Array Self-Recovery Algorithm into an FPGA Controller,” 2010 IEEE AP-S International Symposium on Antennas and Propagation and 2010 USNC/CNC/URSI Meeting, Toronto, ON, Canada, 11-17 July, 2010, pp. 1-4.
  6. M. Joler, C.G. Christodoulou, “On the Development of a Self-Recoverable Antenna System,” 2009 IEEE Antennas and Propagation Society International Symposium, APSURSI'09, Charleston, SC, 1-5 June 2009, Proceedings, pp. 1-4.