Background

Despite the small distance between its ears, a female Ormia ochracea has a remarkable ability to locate male field crickets. Experimental research in [1] explains that this ability arises from the mechanical coupling between the Ormia's ears (Fig. 1) modeled as a system consisting of spring and dashpots. For more details please click here. For our research on Ormia inspired coupled beampattern design click here.

Figure 1: Top: front view of the female Ormia’s ear after the head was removed. Bottom: mechanical model [1].

Our Research

We proposed to design a small-size antenna array having high direction of arrival (DOA) estimation performance, inspired by the Ormia ochracea’s coupled ears, [2], [3], [4], [5].

• Solved the second order differential equations governing the Ormia’s ear response.
• Converted the response to the pre-specified radio frequencies.
• Modeled the biologically inspired coupling as a multi-input multi-output filter on a uniform linear using the converted response.
• Derived the maximum likelihood estimates of source direction of arrivals (DOAs).
• Computed the Cramér-Rao bound (CRB) on DOA estimation error as a performance measure.
• Extended our analysis to consider circular antenna arrays and computed the mean-square angular error (MSAE) bound on the three-dimensional (3D) localization accuracy.
• Proposed an algorithm to optimally choose the biologically inspired coupling for maximum localization performance.

The improvement in the mean-square error in the direction estimation, CRB on DOA estimation error, and MSAE on 3D localization accuracy proves that the BIC improves the direction of arrival estimation performance of the antenna array.

Figure 2: Square-root of the mean-square error in the direction estimation and corresponding CRBs vs. number of time samples for the standard (blue) and BIC (red) uniform linear arrays (5 antennas) with different inter-element spacings, d, and SNR=-10 dB. (a) d = 0.1λ. (b) d = 0.2λ.

Figure 3: Square-root of the CRB on direction of arrival estimation vs. signal-to-noise ratio for standard (blue), and BIC (red) uniform linear arrays (5 antennas) with different inter-element spacings, d = 0.1λ and d = 0.2λ, and N=10 time samples.

Figure 4: Square-root of the MSAE vs. signal-to-noise ratio for the standard (blue), and BIC (red) circular arrays (6 antennas) with different radius values, r = 0.1λ and r = 0.2λ, N=10 time samples

References

1. R. N. Miles, D. Robert, and R. R. Hoy, "Mechanically coupled ears for directional hearing in the parasitoid fly Ormia ochracea," J. Acoust. Soc. Am., vol. 98, no. 6, pp. 3059-3070, 1995.
2. M. Akcakaya, C.H. Muravchik and A. Nehorai, "Biologically inspired coupled antenna array for direction of arrival estimation," IEEE Trans. on Signal Processing, vol. 59, no.10, pp. 4795-4808.

1. M. Akcakaya, C.H. Muravchik and A. Nehorai, "Performance analysis of biologically inspired coupled circular antenna array," Proc. IEEE Antennas and Propagation Society International Symposium (APSURSI), Spokane, WA, USA, July 3-8 2011, pp. 1530-1533.

1. M. Akcakaya, C.H. Muravchik and A. Nehorai, "Biologically inspired direction of arrival estimation," Proc. GOMACTech, Orlando, FL, USA, Mar. 21-24, 2011.
2. M. Akcakaya, C.H. Muravchik and A. Nehorai, "Biologically inspired coupled antenna array for direction of arrival estimation," Proc. 44th Asilomar Conf. Signals, Syst. Comput., Pacific Grove, CA, USA, Nov. 7-10, 2010, pp. 1961-1965.

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