An asymmetrical dipole tag with optimum harmonic conversion efficiency

Extremely small passive dipole tags have been used for tracking insects with a harmonic radar. It will be shown that by adjusting the dipole feed point location, the conversion efficiency, and hence the maximum detection range, can be optimized. Analysis, simulations and measurements on X-band tags confirm that the best tag efficiency is achieved with a half-wavelength dipole and asymmetric 1:2 dipole arm lengths.