Mining Antenna Design Knowledge from
Biological Diversity in Bat Ear Shapes
Rolf Muller
School of Physics & Microelectronics, Shandong University, Jinan, China
In many phylogenetic groups of organisms, common functional principles have been
adapted to suit the needs of a diverse set of ecological niches. Biological diversity there-
fore contains large amounts of valuable design knowledge which can empower the cre-
ation of smart customized technology. The biosonar systems of the more than 1000
bat species support unmatched sensing and communication abilities. In these systems,
beamforming baffle shapes surrounding the sites of sonar-pulse emission (”nose leafs” or
”horseshoes”) and reception (pinnae) play a pivotal role: By determining the spatial dis-
tribution of emitted pulse energy and reception sensitivity, they control the information
available for downstream processing in the brain. Sound diffraction which underlies these
beamforming properties depends solely on the geometry of the tissue-air boundary. There-
fore, knowledge of the nose or ear geometry suffices to evaluate the functional properties
and to unravel the underlying physical mechanisms. An efficient software toolchain has
been developed which automates all steps from converting micro-computer-tomography
data into high-resolution three-dimensional shape representations to numerical analysis
of diffraction and the resulting beam patterns. The toolchain has been used to study
the function of conspicuous features of bat ears such as a prominent tragus, surface rip-
ple, and ledges along the pinna edges. A parametric model which combines some of
these features has been studied and will be used to define a feature space for optimiz-
ing antenna shapes in future research. Furthermore, the efficiency of the toolchain will
be harnessed to analyze a large ensemble of nose and pinna shapes from many differ-
ent bat species. Design rules for antenna shapes can then be mined from the resulting
knowledgebase in a systematic analysis of the joint natural variance in form and function.