Exploitation of nonradiating modes in asymmetric coplanar strip folded dipoles

The asymmetric coplanar strip folded dipole is convenient for matching to balanced coplanar transmission lines as the antenna mode impedance at L/λ=0.5 (where L is the antenna length) can be varied simply by adjusting the relative width of the driven and parasitic elements. It is demonstrated that the electrical length associated with the transmission line mode of the folded dipole can be shortened relative to the antenna mode by adjusting the width of the adjoining conductors between the driven and parasitic arms. The advantage of displacing these modes is that it allows greater flexibility when exploiting the nonradiating folded dipole mode at L/λ=1. A design for a dual band Bluetooth and 802.11a antenna that makes use of this property is presented.