Claims
- 1. A broadband antenna, comprising:
- a feed port including a signal feed portion and a ground portion and having a low impedance;
- an approximately 1/2 wavelength radiator having opposed high impedance ends;
- fixed double resonant broadband transforming means for transforming said low impedance to said high impedance over a wide range of frequencies without tuning, said transforming means coupled between said feed port and said approximately 1/2 wavelength radiator, the broadband transforming means including;
- a first conductive means for resonating at a first frequency, said first conductive means having first and second ends, said first end connected to said signal feed portion of said feed port and said second end coupled to said first end of said 1/2 wavelength radiator; and
- a second conductive means shorter in length than the first conductive means for resonating at a second frequency, said second conductive means having first and second ends, said second conductive means concentrically positioned around a portion of said first conductive means, said first end shorted to said ground portion of said feed port and said second end being open and free from electrical connections.
- 2. The antenna of claim 1, wherein said double resonant transforming means further comprises spacer means, concentrically positioned between said first and second conductive means, for electrically insulating said first and second conductive means, said spacer means being sufficiently thin such that said first conductive means is tightly coupled to said second conductive means so as to broadband the frequency response exhibited by said 1/2 wavelength radiator.
- 3. The antenna of claim 1, wherein said 1/2 wavelength radiator comprises an end-fed dipole.
- 4. An antenna assembly, comprising:
- a feed port including a signal feed portion and a ground portion, said ground portion connected to a ground plane;
- an approximately 1/2 wavelength dipole radiator having first and second high impedance ends;
- a first fixed conductive helix having first and second ends, a first diameter, and exhibiting a first pitch and a first electrical length, said first end coupled to said signal feed portion of said feed port for receiving a radio frequency signal and said second end connected to said first high impedance end of said 1/2 wavelength radiator;
- a second fixed conductive helix shorter in length than the first fixed conductive helix and having first and second ends, a second diameter, and exhibiting a second pitch and a second electrical length, said second conductive helix concentrically wound around a portion of said first conductive helix to form a fixed broadband double resonant transformer which accomplishes broadband performance without tuning, said first end shorted to said ground portion of said feed port and said second end being open and free from electrical connections; and
- spacer means having a thickness and a dielectric constant, concentrically situated between said first and second conductive helixes, for electrically insulating said first and second conductive helixes, said spacer means being sufficiently dimensioned, in said thickness being thin enough, at said dielectric constant, and with said first and second electrical lengths, pitches, and diameters of said first and second helixes, such that said first helix is tightly coupled to said second helix, so as to efficiently broaden the frequency response exhibited by said 1/2 wavelength radiator by minimizing radiation and maximizing phase delays in said double resonant transformer.
- 5. A communication device, comprising:
- a transceiver for providing a radio frequency signal; and an antenna comprising:
- a feed port including a signal feed portion and a ground portion;
- a dipole radiator having an electrical length approximately between 1/2 wavelength .lambda..sub.o and 5/8 wavelength .lambda..sub.o and having first and second high impedance ends;
- a first fixed conductive helix having first and second ends, a first diameter, and exhibiting a first pitch and a first electrical length of approximately 1/4 wavelength .lambda..sub.1, said first end coupled to said signal feed portion of said feed port for receiving said radio frequency signal and said second end connected to said first high impedance end of said radiator; and
- a second fixed conductive helix shorter in length than the first fixed conductive helix and having first and second ends, a second diameter, and exhibiting a second pitch and a second electrical length of approximately 1/4 wavelength .lambda..sub.2, said second conductive helix concentrically wound, around a portion of said first conductive helix to form a fixed and broadband double resonant transformer which provides broadband coupling without tuning, said first end shorted to said ground portion of said feed port and said second end being open and free from electrical connections.
- 6. The communication device of claim 5, further comprising:
- a transmission feed line having inner and outer conductors for coupling said transceiver to said antenna; and
- a coaxial connector terminating said transmission feed line at the upper terminus of the inner and outer conductors, wherein the feed port is located at the upper terminus of said coaxial connector.
- 7. The communication device of claim 5, wherein said second end of said 1/2 wavelength radiator being open and free from electrical connections.
- 8. The communication device of claim 5, wherein said radiator comprises a plurality of dipole elements separated by an 180 degree phase shifter.
- 9. The communication device of claim 5, wherein said second electrical length .lambda..sub.2 /4 of said second helix is substantially shorter than said first electrical length .lambda..sub.1 /4 of said first helix by approximately a factor of 2.
- 10. The communication device of claim 5, wherein said first electrical length .lambda..sub.1 /4 of said first helix is longer than a .lambda..sub.0 /4 of said radiator.
Parent Case Info
This is a continuation of application Ser. No. 08/004,048, filed on Jan. 15, 1993 and now abandoned.
US Referenced Citations (11)
Continuations (1)
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Number |
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Parent |
04048 |
Jan 1993 |
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