Wideband Compact Magnetic Antennas Based on Interdigitated Near-Field Resonant Parasitic Elements

In this paper, compact magnetic antennas based on interdigitated near-field resonant parasitic (NFRP) elements are reported. The electrically small interdigitated NFRP element, driven by the feeding dipole, is first analyzed to validate that it can realize a collaboration of two adjacent resonant modes with stable radiating performance. Based on this, linearly polarized (LP) and circularly (CP) polarized magnetic antennas with boresight radiation performance are further implemented. In detail, the LP version achieves a 14.9%, –10-dB fractional impedance bandwidth (FBW) along with a stable realized gain ~ 6.7 dBi over the frequency band. For the CP version, it achieves an 8.13% 3-dB axial ratio (AR) FBW along with a stable realized gain ~ 6.5 dBi. These compact NFRP antennas can be applied in many high performance highly integrated communication systems.