Tunable omnidirectional antenna

Claim 2

A planar, electrically small, antenna comprising: a. an outer circular arc member having a feed end and a terminating end; b. an inner circular arc member concentric with the said outer circular arc member; c. means for coupling the said inner circular arc member to the said outer circular arc member at the said terminating end of the outer circular arc member; d. an essentially spiral loading element cooperating with the said inner circular arc member; and e. means cooperating with the said terminating end of the outer circular arc member for tuning the said antenna.

Claim 3

The antenna as claimed in claim 1 wherein the radius of the said outer circular arc member is less than one-tenth wavelength.

Claim 4

A tunable, electrically small, high frequency antenna for operation over a determined band of frequencies about a nominal center frequency comprising: a. an outer circular arc conductive member having a radius of less than one-tenth the wavelength of the said nominal center frequency and having a feed end and a terminating end; b. an inner circular arc conductive member concentric with the said outer circular arc member, spaced approximately 0.04 wavelength of the nominal center frequency, from the outer circular arc member, and having a first end adjacent the said feed end of the said outer circular arc member and a second end adjacent the said terminating end of the said outer circular arc member; c. means for loading and coupling the said outer circular arc member and the said inner circular arc member positioned at the said terminal end of the outer circular member and the said second end of the inner circular arc member; d. an essentially planar spiral loading element having a length approximately 0.15 wavelength of the said center frequency in essentially planar relationship with the said outer and inner circular concentric arc members connected to the said second end of the inner circular arc member; and e. means including an inductor and a variable capacitor cooperating with the said terminal end of the outer circular arc member for tuning the antenna over the said band of frequencies.

Claim 5

A tunable, electrically small, high frequency antenna for operation over a determined band of frequencies about a nominal center frequency comprising: a. an outer circular arc conductive member having a radius of less than one-tenth the wavelength of the said nominal center frequency and having a feed end and a terminating end; b. an inner circular arc conductive member concentric with the said outer circular arc member, spaced approximately 0.04 wavelength of the nominal center frequency, from the outer circular arc member, and having a first end adjacent the said feed end of the said outer circular arc member and a second end adjacent the said terminating end of the said outer circular arc member; c. means for loading and coupling the said outer circular arc member and the said inner circular arc member positioned at the said terminal end of the outer circular member and the said second end of the inner circular arc member; d. an essentially planar spiral loading element having a length approximately 0.15 wavelength of the said center frequency in essentially planar relationship with the said outer and inner circular concentric arc members connected to the said second end of the inner circular arc member; and e. means including an inductor and a variable capacitor cooperating with the said terminal end of the outer circular arc member for tuning the antenna over the said band of frequencies.

Claim 6

A tunable, electrically small, high frequency antenna for operating in cooperation with a ground plane, the ground plane being the exterior surface of a vehicle, the antenna being tunable over a determined band of frequencies about a nominal center frequency, the said antenna comprising; a. an outer circular arc conductive member having a radius less than one-tenth the wavelength of the said center frequency, a feed end located at the said ground plane, and a terminating end located approximately 170* of arc from the said feed end; b. an inner circular arc conductive member concentric with the said outer circular member and spaced therefrom approximately 0.04 wavelength of the said center frequency having a first end adjacent the said ground plane and a second end adjacent the said terminating end of the outer circular arc member; c. a parallel loading and coupling member cooperating with the said terminating end of the outer circular arc member and the said second end of the inner circular arc member, the said parallel loading and coupling member being planaR with and located between the outer and inner circular arc members; d. an essentially spiral loading member planar with the outer and inner circular arc members, have a length of approximately 0.15 wavelength of the said center frequency connected with the said first end of the inner circular arc member and terminated to the said ground plane; and e. means including an inductor and a variable capacitor, located below the said ground plane, connected to the said terminating end of the outer circular arc member and to the said ground plane for tuning the said antenna over the determined band of frequencies.

Claim 7

A tunable, electrically small, high frequency antenna for operating in cooperation with a ground plane, the ground plane being the exterior surface of a vehicle, the antenna being tunable over a determined band of frequencies about a nominal center frequency, the said antenna comprising; a. an outer circular arc conductive member having a radius less than one-tenth the wavelength of the said center frequency, a feed end located at the said ground plane, and a terminating end located approximately 170* of arc from the said feed end; b. an inner circular arc conductive member concentric with the said outer circular member and spaced therefrom approximately 0.04 wavelength of the said center frequency having a first end adjacent the said ground plane and a second end adjacent the said terminating end of the outer circular arc member; c. a parallel loading and coupling member cooperating with the said terminating end of the outer circular arc member and the said second end of the inner circular arc member, the said parallel loading and coupling member being planaR with and located between the outer and inner circular arc members; d. an essentially spiral loading member planar with the outer and inner circular arc members, have a length of approximately 0.15 wavelength of the said center frequency connected with the said first end of the inner circular arc member and terminated to the said ground plane; and e. means including an inductor and a variable capacitor, located below the said ground plane, connected to the said terminating end of the outer circular arc member and to the said ground plane for tuning the said antenna over the determined band of frequencies.

Claim 8

The antenna as claimed in claim 4 wherein the free resonance range of the said inductor and variable capacitor essentially encompasses the frequency range of the said determined bandwidth.