Multi-mode antenna and multi-band antenna combination
The present invention is to provide a combination antenna having multi-mode and multi-band arrangements, which comprises a conductive seat; a non-uniform helical antenna extending from one end of the conductive seat; and a pole antenna extending from one end of the conductive seat through the helical antenna, enabling to be tuned to three or more resonant frequencies through tuning the helical antenna to a plurality of resonant frequencies and tuning the pole antenna to a plurality of resonant frequencies different from that to which the helical antenna is tuned.
1. A combination antenna having multi-mode and multi-band arrangements, comprising:
a conductive seat;
a non-uniform helical antenna extending from one end of the conductive seat, the helical antenna comprising a first coil section and a second coil section, wherein the first coil section has a spiral angle less than a spiral angle of the second coil section, a pitch less than a pitch of the second coil section, and coils arranged in a more dense arrangement as compared to that of the second coil section such that the first coil section is adapted to be tuned to a plurality of resonant frequencies different from that to which the second coil section is adapted to be tuned; and
a pole antenna extending from one end of the conductive seat through the helical antenna, a plurality of physical parameters of the pole antenna capable of being adjusted for tuning the pole antenna to a plurality of resonant frequencies different from that to which the helical antenna is tuned,
wherein the characteristic of the helical antenna depends on a ratio (D/λ) of coil diameter D to wavelength λ, the ratio D/λ is less than 1.8, and electric field and direction coefficients of the helical antenna are represented as:
l
2
=
S
2
+
(
π
D
)
2
=
(
S
Sin
θ
)
2
h
=
NS
}
E
φ
=
120
π
2
I
r
A
λ
2
Sin
θ
E
θ
=
j
60
π
I
r
S
λ
Sin
θ
where D is average coil diameter, S is pitch, h is axial length, l is average length of coil, θ is spiral angle, and N is the number of turns.
2. The combination antenna of claim 1 wherein in the helical antenna a first unit consists of a plurality of coils of the first coil section and a plurality of coils of the second coil section, and a second unit consists of a total pitch length of the coils of the first coil section and a total pitch length of the coils of the second coil section, and wherein the helical antenna is adapted to be tuned to two resonant frequencies via the first and second units.
3. The combination antenna of claim 2 wherein the first coil section has five coils and the second coil section has four coils.
4. The combination antenna of claim 1 , further comprising a feed point electrically connected to one end of the pole antenna, wherein an equivalent length of the feed point and the pole antenna is formed such that it is adapted to tune the pole antenna to a plurality of resonant frequencies different from that to which the helical antenna is tuned via the pole antenna and the feed point in the equivalent length.
5. A combination antenna having multi-mode and multi-band arrangements, comprising:
a conductive seat;
a non-uniform helical antenna extending from one end of the conductive seat, the helical antenna comprising a first coil section and a second coil section having a plurality of physical parameters different from that of the first coil section such that the first coil section is adapted to be tuned to a plurality of resonant frequencies different from that to which the second coil section is adapted to be tuned; and
a pole antenna extending from one end of the conductive seat through the helical antenna, a plurality of physical parameters of the pole antenna capable of being adjusted for tuning the pole antenna to a plurality of resonant frequencies different from that to which the helical antenna is tuned,
wherein the pole antenna is a monopole antenna of one quarter wavelength (λ) mounted on a PCB, wherein a radiation element of half wavelength is created by the pole antenna and the PCB, and wherein electric field and direction coefficients of the pole antenna are represented as:
E
θ
=
∫
-
l
l
ⅆ
E
θ
=
j
60
I
m
r
cos
(
kl
cos
θ
)
-
cos
kl
sin
θ
ⅇ
-
j
kr
E
θ
=
f
(
θ
)
f
max
=
1
f
max
cos
(
kl
cos
θ
-
cos
kl
)
sin
θ
F
(
θ
)
=
cos
(
π
2
cos
θ
)
sin
θ
where I m is current at valley of an equivalent current waveshape, k is propagation constant, and 1 is equivalent length of a monopole.
6. The combination antenna of claim 5 , further comprising a feed point electrically connected to one end of the pole antenna, wherein an equivalent length of the feed point and the pole antenna is formed such that it is adapted to tune the pole antenna to a plurality of resonant frequencies different from that to which the helical antenna is tuned via the pole antenna and the feed point in the equivalent length.