Communication device
A communication device includes a circularly polarized antenna with a first antenna element and a second antenna element disposed orthogonally to the first antenna element; and a phase shifter that includes a capacitor connected to the first antenna element, and an inductor connected to the second antenna element, in which in a case where a resistance is denoted by R, an imaginary unit is denoted by j, a reactance is denoted by X, a center frequency of the antenna is denoted by f, a capacitance is denoted by C, and an inductance is denoted by L, an impedance of the antenna is represented by R+jX, a capacitance of the capacitor is a value calculated by C=1/{πf(R+X)}, and an inductance of the inductor is a value calculated by L=(R−X)/(4πf).
1 . A communication device comprising:
a circularly polarized antenna that includes
a first antenna element, and
a second antenna element disposed orthogonally to the first antenna element; and
a phase shifter that includes
a capacitor connected to the first antenna element, and
an inductor connected to the second antenna element,
wherein in a case where a resistance is denoted by R, an imaginary unit is denoted by j, a reactance is denoted by X, a center frequency of the antenna is denoted by f, a capacitance is denoted by C, and an inductance is denoted by L,
an impedance of the antenna is represented by R+jX,
a capacitance of the capacitor is a value calculated by C=1/{πf(R+X)}, and
an inductance of the inductor is a value calculated by L=(R−X)/(4πf).
2 . The communication device according to claim 1 ,
wherein the antenna is a balanced antenna.
3 . The communication device according to claim 1 ,
wherein the capacitor and the inductor are short-circuited.
4 . The communication device according to claim 1 ,
wherein each of the first antenna element and the second antenna element is a dipole antenna,
each of two radiation elements included in the first antenna element is connected to the capacitor, and
each of two radiation elements included in the second antenna element is connected to the inductor.
5 . The communication device according to claim 1 , further comprising
a balun that is connected to the phase shifter.
6 . The communication device according to claim 5 , further comprising
a matching circuit that is connected to the balun.
7 . The communication device according to claim 1 ,
wherein at least one of the capacitor or the inductor is variable.
8 . The communication device according to claim 1 ,
wherein a resistor that has a resistance value corresponding to an equivalent series resistance of the inductor is connected to the capacitor.
9 . The communication device according to claim 1 ,
wherein the inductor includes a plurality of the inductors that is connected in parallel or in series.
10 . The communication device according to claim 1 , further comprising
a power generation unit,
wherein the antenna is a propeller antenna, and
the power generation unit generates power by rotation of the propeller antenna.
11 . A communication device comprising:
a circularly polarized antenna that includes a first orthogonally linearly polarized antenna element and a second orthogonally linearly polarized antenna element; and
a phase shifter that includes
a capacitor connected to the first antenna element, and
an inductor connected to the second antenna element,
wherein in a case where a resistance is denoted by R, an imaginary unit is denoted by j, a reactance is denoted by X, a center frequency of the antenna is denoted by f, a capacitance is denoted by C, and an inductance is denoted by L,
an impedance of the antenna is represented by R+jX,
a capacitance of the capacitor is a value calculated by C=1/{2πf(R+X)}, and
an inductance of the inductor is a value calculated by L=(R−X)/(2πf).
12 . The communication device according to claim 11 ,
wherein the antenna is an unbalanced antenna.
13 . The communication device according to claim 11 ,
wherein each of the first antenna element and the second antenna element is a microstrip antenna.
14 . The communication device according to claim 11 ,
wherein each of the first antenna element and the second antenna element is a monopole antenna.
15 . The communication device according to claim 11 ,
wherein the capacitor and the inductor are short-circuited.
16 . The communication device according to claim 11 ,
wherein at least one of the capacitor or the inductor is variable.