Short Asymmetrical Inductive Dipole Antenna for Direct Matching to High-Q Chips

A planar antenna structure based on a folded asymmetrical dipole is presented, whose geometrical parameters are seen to independently determine either the real or the imaginary parts of the complex radiation impedance. This unique feature allows very efficient and wideband conjugate matching coupling to nonconventional RF sources of arbitrary internal impedance, i.e., small resistance with large and negative reactance. The antenna theoretical framework is developed and an optimized design to match a photodiode is manufactured and measured. The results show a fractional bandwidth of about 20% in the 28 GHz band.