Patent ID: 6677901
Filing Date: 2004-01-13
Classification: H01Q

Abstract:
An electrically small, compact planar tunable microstrip antenna, comprising:a microstrip dielectric substrate sandwiched between a radiating element and a conductive ground plane; said microstrip dielectric substrate, being composed of a material having a relative dielectric constant, âˆˆr, similar to a relative magnetic permeability, &mgr;r, where said âˆˆr>1.0 and said &mgr;r>1.0, forming a permittivity to permeability ratio of between about 1:1 and about 1:3, said material being selected from group of materials consisting of ferrite compounds and ferrite-ferroelectric composite compounds; a means for tuning; said antenna having a given length, Al; said radiating element having a narrow portion and a wide portion; said narrow portion having a shorted end shorted to said ground plane, and said wide portion, having a central region near said narrow portion and a junction point opposing said shorted end, provides a given impedance; said dielectric substrate having an effective impedance value and a decreased wavelength due to said permittivity to permeability ratio; said narrow portion causing a reduced effective impedance at said junction point; and said decreased wavelength, a refractive index factor and said reduced impedance permitting a reduced antenna length, Ar, that operates at HF and VHF frequencies.