Substrate antenna with fed and non-fed elements having slits

摘要

A multi frequency surface mount antenna 1 formed on a dielectric substrate 2 includes at least one planar fed radiating element 3 and at least one planar non-fed radiating element 4 which is electromagnetically coupled to the fed element. The fed element 3 has a feed 5 provided at one end. The non-fed element 4 is grounded 6. Both elements have a folded slit 12,14 defining a gap in their conductive surfaces which thus form generally spiral patterns 11,13. Each of the elements radiates at first frequency, and a second frequency determined by the width of the slit and the dielectric constant. The dielectric constant also determines the amount of coupling between the elements. Capacity loaded electrodes (16,17) define capacitors between the elements and ground, the adjustment of capacity adjusting the first and second resonant frequencies. The resonant frequencies of the non-fed element 4 extend the frequency bandwidth.