Dual-band interspersed cellular basestation antennas
Low-band radiators of an ultra-wideband dual-band dual-polarization cellular basestation antenna are provided. The dual bands include low and high bands. The low-band radiator includes a dipole with two dipole arms adapted for the low band and for connection to an antenna feed. At least one dipole arm of the dipole includes at least two dipole segments and at least one radio frequency choke. The choke is disposed between the dipole segments. Each choke provides an open circuit or a high impedance separating adjacent dipole segments to minimize induced high band currents in the low-band radiator and consequent disturbance to the high band pattern. The choke is resonant at or near the frequencies of the high band.
1. A low-band radiator of an ultra-wideband dual-band dual-polarization cellular basestation antenna, said dual bands comprising low and high bands, said low-band radiator comprising:
a dipole antenna comprising a first dipole arm and a second dipole arm adapted for said low band and for connection to an antenna feed;
wherein the first dipole arm comprises:
at least three dipole segments; and
at least two radio frequency (RF) chokes,
wherein adjacent dipole segments of the at least three dipole segments are separated by respective ones of the at least two RF chokes to reduce induced high band currents in said low-band radiator and consequent disturbance to the high band, said at least two RF chokes being resonant at or near the frequencies of said high band,
wherein the adjacent dipole segments of the at least three dipole segments are spaced apart such that there is a gap between the adjacent dipole segments.
2. The low-band radiator as claimed in claim 1 , wherein each dipole segment of the at least three dipole segments comprises an electrically conducting elongated body, said elongated body being open circuited at one end and short circuited at another end to a center conductor.
3. The low-band radiator as claimed in claim 2 , wherein each electrically conducting elongated body is cylindrical or tubular in form.
4. The low-band radiator as claimed in claim 3 , wherein the space between each cylindrical conducting body and said center conductor is filled with air.
5. The low-band radiator as claimed in claim 2 , wherein said center conductor connects to said other end that is short circuited to the center conductor.
6. The low-band radiator as claimed in claim 2 , wherein said center conductor is an elongated cylindrical electrically conducting body.
7. The low-band radiator as claimed in claim 6 , wherein the center conductor has a thickness adapted to provide immunity from disturbance of the high-band by said low-band radiator over the entire high-band bandwidth.
8. The low-band radiator as claimed in claim 2 , wherein said conducting body and a center conductor of each dipole segment of the at least three dipole segments have dimensions such that a radiation pattern of said high band is undisturbed by the presence of said low-band radiator.
9. The low-band radiator as claimed in claim 1 , wherein each RF choke contains lumped circuit elements, or is an open sleeve partly or completely enclosing a center conductor.
10. The low-band radiator as claimed in claim 1 , adapted for the frequency range of 698-960 MHz.
11. The low-band radiator as claimed in claim 1 , wherein said dipole antenna is an extended dipole and further comprising another dipole comprising a third dipole arm and a fourth dipole arm that are configured in a cross configuration with the first dipole arm and the second dipole arm,
wherein the third dipole arm and the fourth dipole arm are resonant at approximately a quarter wavelength (λ/4)
wherein the extended dipole antenna further comprises anti-resonant dipole arms of approximately a half-wavelength (λ/2) length.
12. A low-band radiator of an ultra-wideband dual-band dual-polarization cellular basestation antenna, said dual bands comprising low and high bands, said low-band radiator comprising:
a dipole antenna comprising a first dipole arm and a second dipole arm adapted for said low band and for connection to an antenna feed;
wherein the first dipole arm comprises:
at least two dipole segments; and
at least one radio frequency (RF) choke disposed between said at least two dipole segments,
wherein adjacent dipole segments of the at least two dipole segments are separated by one of the at least one RF choke to reduce induced high band currents in said low-band radiator and consequent disturbance to the high band, said at least one RF choke being resonant at or near the frequencies of said high band,
wherein the one of the at least one RF choke is a coaxial choke comprising a protruding portion of center conductor extending between adjacent dipole segments by a gap, the coaxial choke having a length of a quarter wavelength (λ/4) or less at frequencies in the bandwidth of the high band.
13. A low-band radiator of an ultra-wideband dual-band dual-polarization cellular basestation antenna, said dual bands comprising low and high bands, said low-band radiator comprising:
a dipole antenna comprising a first dipole arm and a second dipole arm adapted for said low band and for connection to an antenna feed;
wherein the first dipole arm comprises:
at least two dipole segments; and
at least one radio frequency (RF) choke disposed between said at least two dipole segments,
wherein adjacent dipole segments of the at least two dipole segments are separated by one of the at least one RF choke to reduce induced high band currents in said low-band radiator and consequent disturbance to the high band, said at least one RF choke being resonant at or near the frequencies of said high band,
wherein each dipole segment of the at least two dipole segments comprises an electrically conducting elongated body that is cylindrical or tubular in form, said elongated body being open circuited at one end and short circuited at the other end to a center conductor,
wherein the space between each cylindrical conducting body and said center conductor is filled or partly filled with dielectric material.