JP4733537B2 - Folded antenna device - Google Patents

Description

  The present invention relates to a folded antenna device capable of adjusting a resonance frequency.

  A folded antenna having a configuration in which a linear conductor is folded is widely used. FIG. 6 shows an example of the folded antenna. The folded antenna includes linear conductors C1 and C2, an input / output terminal IO, and a ground conductor G. The linear conductors C1 and C2 have a length of about one quarter of the wavelength of electromagnetic waves to be transmitted and received. The linear conductors C1 and C2 are arranged in parallel with a distance such that they are electrically and magnetically coupled. One end C1O of the linear conductor C1 is connected to one end C2O of the linear conductor C2. An end C2S of the linear conductor C2 opposite to the side connected to the linear conductor C1 is connected to the input / output terminal IO of the folded antenna. An end C1S of the linear conductor C1 opposite to the side connected to the linear conductor C2 is connected to the ground conductor G. A radio signal transmitted by the folded antenna is input between the input / output terminal IO and the ground conductor G, and a radio signal received by the folded antenna is output between the input / output terminal IO and the ground conductor G.

  The impedance viewed from the folded antenna between the input / output terminal IO and the ground conductor G is such that the cross-section perpendicular to the longitudinal direction of the linear conductors C1 and C2 is circular. It can be adjusted by changing the ratio of the wire diameter of the wire conductor C2 and the like.

Japanese Patent Laid-Open No. 10-079622

  The energy of the electromagnetic wave radiated from the antenna or the energy of the electromagnetic wave received by the antenna is maximized when the resonance frequency of the antenna matches the frequency of the electromagnetic wave transmitted and received. Therefore, in antennas applied to wireless devices that transmit and receive wireless signals over a wide frequency band, the resonance frequency can be adjusted while minimizing the effects on antenna transmission and reception characteristics such as directivity and input impedance. It is preferable that

  The present invention has been made with respect to such a problem, and provides a folded antenna device capable of adjusting a resonance frequency while minimizing an influence on antenna transmission / reception characteristics.

The present invention includes: a first antenna element having two connection ends; and a second antenna element arranged to be electrically and magnetically coupled to the first antenna element and having two connection ends. A connection end of one of the two connection ends included in the first antenna element and a connection end of one of the two connection ends included in the second antenna element are connected, and Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is defined as an input / output end, and the second antenna element includes Of the two connection ends, a folded antenna device in which a connection end that is not connected to one of the two connection ends included in the first antenna element is connected to a ground conductor, wherein the first antenna element is Applied A variable capacitance element whose capacitance changes according to a voltage; and an element element which is connected to the variable capacitance element and forms the first antenna element. The second antenna element has a capacitance according to an applied voltage. A variable capacitance element that changes, and an element element that is connected to the variable capacitance element and forms the second antenna element, and an antenna of the folded antenna device is provided between the input / output end and the ground conductor. The folded antenna device includes a choke inductor connected to the input / output end, and a voltage applied between the terminal of the choke inductor on the side not connected to the input / output end and the ground conductor. By changing the capacitance of the variable capacitance element included in the first antenna element and the capacitance of the variable capacitance element included in the second antenna element. Folded antenna device being characterized in that a possible integer.

The present invention also provides a first antenna element having two connection ends, and a second antenna element having two connection ends arranged to be electrically and magnetically coupled to the first antenna element. , And one connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected to each other. Of the two connection ends provided in the first antenna element, the connection end not connected to one of the two connection ends provided in the second antenna element is defined as an input / output end, and the second antenna element is provided. Of the two connection ends included in the first antenna element, and two antenna one side portions having a connection end that is not connected to one of the two connection ends included in the first antenna element as a common connection end. One side is that A folded antenna device connected at the common connection end, wherein the first antenna element is connected to a variable capacitance element whose capacitance changes according to an applied voltage, the variable capacitance element, and the first antenna element. The second antenna element is connected to the variable capacitance element, and the second antenna element is connected to the variable capacitance element. The input / output ends provided in each of the two antenna one side portions are used as the antenna input / output ends of the folded antenna device, and the folded antenna device is provided in the antenna input / output end 2. A first choke inductor connected to one of the two input / output terminals, and the two input / output terminals of the antenna input / output terminal. A second choke inductor connected to an input / output end to which the first choke inductor is not connected, a terminal not connected to the antenna input / output end of the first choke inductor, and the second choke inductor Of the variable capacitance element included in the first antenna element and the variable capacitance element included in the second antenna element by changing a voltage applied between the terminal and the terminal not connected to the antenna input / output terminal. The capacity is adjustable.

The present invention also provides a first antenna element having two connection ends, and a second antenna element having two connection ends arranged to be electrically and magnetically coupled to the first antenna element. , And one connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected to each other. Of the two connection ends provided in the first antenna element, the connection end not connected to one of the two connection ends provided in the second antenna element is defined as an input / output end, and the second antenna element is provided. A folded antenna device in which a connection end that is not connected to one of the two connection ends included in the first antenna element is connected to a ground conductor.
The first antenna element includes: a variable capacitance element whose capacitance changes according to an applied voltage; and an element element that is connected to the variable capacitance element and forms the first antenna element. The antenna element includes: a variable capacitance element whose capacitance changes according to an applied voltage; and an element element connected to the variable capacitance element and constituting the second antenna element, the input / output terminal and the ground conductor Between the antenna input and output ends of the folded antenna device,
By changing the capacitance of the variable capacitance element included in each of the first antenna element and the second antenna element, both the current flowing in the first antenna element and the current flowing in the second antenna element are changed. The resonance frequency based on this can be adjusted .

Further, in the folded antenna device according to the present invention, a voltage applied between the terminal of the choke inductor on the side not connected to the input / output terminal and the ground conductor is provided with the choke inductor connected to the input / output terminal. It is preferable that the capacitance of the variable capacitance element included in the first antenna element and the capacitance of the variable capacitance element included in the second antenna element can be adjusted by changing the above.

The present invention also includes a first antenna element having two connection ends, a second antenna element having two connection ends arranged to be electrically and magnetically coupled to the first antenna element, And one connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected, Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is defined as an input / output end, and the second antenna element is Two antenna one side portions having a common connection end that is a connection end that is not connected to one of the two connection ends included in the first antenna element among the two connection ends provided. Each part A folded antenna device connected at the common connection end, wherein the first antenna element is connected to a variable capacitance element whose capacitance changes according to an applied voltage, the variable capacitance element, and the first antenna element. The second antenna element is connected to the variable capacitance element, and the second antenna element is connected to the variable capacitance element. And the input / output ends provided in each of the two antenna one side portions are used as antenna input / output ends of the folded antenna device, and the first antenna element and the second antenna element are provided. By changing the capacitance of the variable capacitance element included in each, the current flowing through the first antenna element and the current flowing through the second antenna element Characterized in that the resonant frequency based on both the current and adjustable.

Further, in the folded antenna device according to the present invention, a first choke inductor connected to one of the two input / output terminals provided in the antenna input / output terminal, and two antenna input / output terminals provided in the antenna input / output terminal A second choke inductor connected to an input / output terminal to which the first choke inductor is not connected, and a terminal not connected to the antenna input / output terminal of the first choke inductor; By changing a voltage applied between the second choke inductor and a terminal not connected to the antenna input / output terminal, the capacitance of the variable capacitance element included in the first antenna element and the second antenna are changed. It is preferable that the capacitance of the variable capacitance element included in the element can be adjusted. In the folded antenna device according to the present invention, it is preferable that the element elements constituting the first antenna element and the element elements constituting the second antenna element are constituted by linear conductors. It is. In the folded antenna device according to the present invention, it is preferable that the element element constituting the first antenna element and the element element constituting the second antenna element are arranged in parallel to each other. It is.

The present invention also provides a first antenna element having two connection ends, and a second antenna element having two connection ends arranged to be electrically and magnetically coupled to the first antenna element. , And one connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected to each other. Of the two connection ends provided in the first antenna element, the connection end not connected to one of the two connection ends provided in the second antenna element is defined as an input / output end, and the second antenna element is provided. A folded antenna device in which a connection end that is not connected to one of the two connection ends included in the first antenna element is connected to a ground conductor.
The first antenna element includes: a variable capacitance element whose capacitance changes according to an applied voltage; and an element element that is connected to the variable capacitance element and forms the first antenna element. The antenna element includes: a variable capacitance element whose capacitance changes according to an applied voltage; and an element element connected to the variable capacitance element and constituting the second antenna element, the input / output terminal and the ground conductor And the element element constituting the first antenna element and the element element constituting the second antenna element are constituted by a spiral inductor. It is characterized by that. The present invention also provides a first antenna element having two connection ends, and a second antenna element having two connection ends arranged to be electrically and magnetically coupled to the first antenna element. , And one connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected to each other. Of the two connection ends provided in the first antenna element, the connection end not connected to one of the two connection ends provided in the second antenna element is defined as an input / output end, and the second antenna element is provided. Of the two connection ends included in the first antenna element, and two antenna one side portions having a connection end that is not connected to one of the two connection ends included in the first antenna element as a common connection end. One side is that A folded antenna device connected at the common connection end, wherein the first antenna element is connected to a variable capacitance element whose capacitance changes according to an applied voltage, the variable capacitance element, and the first antenna element. The second antenna element is connected to the variable capacitance element, and the second antenna element is connected to the variable capacitance element. An element input / output terminal, and the input / output ends included in each of the two antenna one side portions are used as antenna input / output ends of the folded antenna device, and the element elements configuring the first antenna element and The element element constituting the second antenna element is constituted by a spiral inductor. Further, in the folded antenna device according to the present invention, a voltage applied between the terminal of the choke inductor on the side not connected to the input / output terminal and the ground conductor is provided with the choke inductor connected to the input / output terminal. It is preferable that the capacitance of the variable capacitance element included in the first antenna element and the capacitance of the variable capacitance element included in the second antenna element can be adjusted by changing the above. Further, in the folded antenna device according to the present invention, a first choke inductor connected to one of the two input / output terminals provided in the antenna input / output terminal, and two antenna input / output terminals provided in the antenna input / output terminal A second choke inductor connected to an input / output terminal to which the first choke inductor is not connected, and a terminal not connected to the antenna input / output terminal of the first choke inductor; By changing a voltage applied between the second choke inductor and a terminal not connected to the antenna input / output terminal, the capacitance of the variable capacitance element included in the first antenna element and the second antenna are changed. It is preferable that the capacitance of the variable capacitance element included in the element can be adjusted .

  According to the present invention, the resonance frequency of the folded antenna device can be changed by changing the capacitance of the variable capacitance element. Therefore, the energy of electromagnetic waves to be transmitted and received can be optimally adjusted in a wide frequency band.

  FIG. 1 is a perspective view of the linear folded antenna 100 according to the first embodiment, and FIG. 2A is a side view of the linear folded antenna 100. However, in FIG. 2A, a cross section of the ground conductor 24 is shown. The folded antenna 100 includes linear conductors 10a, 10b, 10c, 10d, 12, variable capacitance diodes 14a, 14b, input / output conductor 16, DC blocking capacitor 18, input / output terminal 20, choke inductor 22, ground conductor 24, and connection. Tubes 26a and 26b and a variable DC voltage source 28 are provided. The ground conductor 24 is provided with an input / output hole 30. FIG. 2 (b) shows an enlarged view of the inside of the connecting cylinders 26a and 26b between the straight line ef and the straight line gh in FIG. 2 (a).

  The linear conductors 10a and 10b have a circular shape with a radius r1 in the cross section perpendicular to the extending direction, and the lengths thereof are La and Lb, respectively. The linear conductors 10c and 10d are circular with a radius r2 in a cross section perpendicular to the extending direction, and the lengths thereof are Lc and Ld, respectively. In addition, the length of the linear conductor 12 is Dcp1.

  The linear conductor 10a is fixed to the ground conductor 24 perpendicular to the surface S of the ground conductor 24 at the end T1. A connecting tube 26a is attached to an end T2 opposite to the end T1 fixed to the ground conductor 24 of the linear conductor 10a. The linear conductor 10b is attached to the connecting cylinder 26a so that the ends T2 and T3 of the linear conductors 10a and 10b are separated from each other by a distance δ, and the extending direction coincides with the extending direction of the linear conductor 10a. A variable capacitance diode 14a is accommodated in the space inside the connecting tube 26a between the ends T2 and T3.

  The linear conductor 12 is fixed to the end T4 of the linear conductor 10b opposite to the end T3, perpendicular to the linear conductor 10b. The linear conductor 10c is fixed to the linear conductor 12 at its end T5 so as to be parallel to the linear conductor 10b and perpendicular to the linear conductor 12. A connecting tube 26b is attached to an end T6 of the linear conductor 10c opposite to the end T5 fixed to the linear conductor 12. The linear conductor 10d is attached to the connecting cylinder 26b so that the ends T6 and T7 of the linear conductors 10c and 10d are separated from each other by a distance δ, and the extending direction coincides with the extending direction of the linear conductor 10c. The variable capacitance diode 14b is accommodated in the space inside the connecting tube 26b between the end T6 and the end T7. The input / output conductor 16 is connected to the end T8 opposite to the end T7 of the linear conductor 10d. The input / output conductor 16 passes through the input / output hole 30 to the opposite side of the surface S.

  The connecting cylinders 26a and 26b are preferably formed of a dielectric having a relative dielectric constant close to 1. The lengths of the connecting cylinders 26a and 26b are sufficiently shorter than the wavelength of electromagnetic waves to be transmitted and received. A distance δ between the end T2 and the end T3 and a distance δ between the end T6 and the end T7 are sufficiently shorter than the wavelength of the electromagnetic wave to be transmitted and received.

  Each of the lengths La to Ld of the linear conductors 10a to 10d has a variable range of the capacitance of the variable capacitance diode 14a and a variable capacitance diode so that the resonance frequency of the linear folded antenna 100 is included in the frequency band of electromagnetic waves to be transmitted and received. It is determined together with the variable range of the capacity of 14b. It is preferable that the length La of the linear conductor 10a and the length Ld of the linear conductor 10d are the same, and the length Lb of the linear conductor 10b and the length Lc of the linear conductor 10c are the same.

  The length Dcpl of the linear conductor 12 is set such that the linear conductors 10a and 10d and the linear conductors 10b and 10c are electrically and magnetically coupled. Here, “electrically coupled” means a state in which a capacitance can be formed between two conductors. Magnetic coupling refers to a state in which mutual inductance can be formed between two conductors. In this case, the distance between the linear conductor 10a and the linear conductor 10d and the distance between the linear conductor 10b and the linear conductor 10c are determined from the length Dcp1 of the linear conductor 12 to the linear conductor 10b. A value obtained by subtracting the wire diameter r1 and the wire diameter r2 of the linear conductor 10c, that is, a distance represented by D = Dcpl-r1-r2, is arranged.

  The length Dcpl of the linear conductor 12 is set so that the impedance of the linear conductors 10a to 10d between the input / output terminal 20 and the ground conductor 24 when viewed from the side of the linear folded antenna 100 becomes a desired value. It is determined together with the lengths La to Ld, the wire diameter r1 of the linear conductors 10a and 10b, the wire diameter r2 of the linear conductors 10c and 10d, the variable range of the capacitance of the variable capacitance diode 14a, and the variable range of the capacitance of the variable capacitance diode 14b. .

  Here, the linear conductor 10a is fixed to the ground conductor 24, and the linear conductors 10b, 10c, and 10d are fixed by the connecting tubes 26a and 26b and the linear conductor 12. In addition to such a configuration, the connection cylinders 26a and 26b are not provided, and the linear conductors 10a to 10d, 12, the variable capacitance diode 14a, and the variable capacitance diode 14b are molded with a dielectric or the like, and the linear conductors 10a to 10a. A configuration in which 10d, 12, the variable capacitance diode 14a and the variable capacitance diode 14b are fixed on the surface of the dielectric substrate is also possible. Further, the linear conductors 10a to 10d have a circular shape in a cross section perpendicular to the extending direction, but are not necessarily circular, and may have any shape.

  Further, instead of the variable capacitance diode, a circuit element whose capacitance is changed by a change in applied voltage can be applied. Such circuit elements include transistors.

  The electrical connection of the linear folded antenna 100 will be described. The end T1 of the linear conductor 10a is connected to the ground conductor 24. The end T2 of the linear conductor 10a is connected to the anode terminal A of the variable capacitance diode 14a. The cathode terminal K of the variable capacitance diode 14a is connected to the end T3 of the linear conductor 10b. The end T4 of the linear conductor 10b is connected to the end T5 of the linear conductor 10c through the linear conductor 12. The end T6 of the linear conductor 10c is connected to the anode terminal A of the variable capacitance diode 14b. The cathode terminal K of the variable capacitance diode 14b is connected to the end T7 of the linear conductor 10d.

  An input / output conductor 16 is connected to the end T8 of the linear conductor 10d. A choke inductor 22 and a DC blocking capacitor 18 are connected to the input / output conductor 16. A variable DC voltage source 28 is connected between the terminal of the choke inductor 22 that is not connected to the input / output conductor 16 and the ground conductor 24. An input / output terminal 20 is connected to a terminal of the DC blocking capacitor 18 that is not connected to the input / output conductor 16.

  The inductance value of the choke inductor 22 is such that the absolute value of the impedance at the frequency of the electromagnetic wave to be transmitted and received is sufficiently larger than the absolute value of the impedance viewed from the side of the linear conductor 10d between the end T8 and the ground conductor 24. It is preferable to set it to a small value. The absolute value of the impedance of the DC blocking capacitor 18 at the frequency of the electromagnetic wave to be transmitted and received is sufficiently smaller than the absolute value of the impedance viewed from the side of the linear conductor 10d between the end T8 and the ground conductor 24. Such a value is preferable. The capacitance value of the DC blocking capacitor 18 may be a value for matching with the antenna connection terminal of the wireless device connected to the linear folded antenna 100.

  The operation of the linear folded antenna 100 will be described. The variable DC voltage source 28 applies a DC voltage between the end T8 of the linear conductor 10d and the end T1 of the linear conductor 10a via the choke inductor 22 and the input / output conductor 16. The polarity of the DC voltage is positive on the choke inductor 22 side. As a result, a reverse bias DC voltage is applied to the variable capacitance diodes 14a and 14b. The variable capacitance diodes 14a and 14b have a capacity according to the DC voltage.

  A radio signal is input between the input / output terminal 20 and the ground conductor 24 as an unbalanced mode signal. Here, the signal in the unbalanced mode generally refers to a signal in a transmission form in which transmission is performed between a conductor that provides a ground potential and a line conductor that provides a signal potential. The radio signal is transmitted between the end T8 of the linear conductor 10d and the ground conductor 24 via the DC blocking capacitor 18 and the input / output conductor 16, and a current Iin flows through the end T8 based on the radio signal.

  Due to the current Iin, the common mode current I1X and the differential mode current I2X flow through the linear conductor 10a and the variable capacitance diode 14a, and the common mode current I1Y and the differential mode current I2Y flow through the linear conductor 10d and the variable capacitance diode 14b. Flowing. The common mode currents I1X and I1Y are currents having the same phase relationship in a common cross section perpendicular to the extending direction of the linear conductors 10a and 10d. On the other hand, the differential mode currents I2X and I2Y are currents having the same amplitude and opposite phase in a common cross section perpendicular to the extending direction of the linear conductors 10a and 10d.

  Similarly, the common mode current I1X and the differential mode current I2X flow through the linear conductor 10b, and the common mode current I1Y and the differential mode current I2Y flow through the linear conductor 10c. The common mode currents I1X and I1Y are currents having the same phase relationship in a common cross section perpendicular to the extending direction of the linear conductors 10b and 10c. On the other hand, the differential mode currents I2X and I2Y are currents having the same amplitude and opposite phase in a common cross section perpendicular to the extending direction of the linear conductors 10b and 10c.

  Electromagnetic waves are radiated from the linear folded antenna 100 by the common mode currents I1X and I1Y. On the other hand, the differential mode currents I2X and I2Y do not directly contribute to the emission of electromagnetic waves, but the electromagnetic wave energy is retained in the vicinity of the linear conductors 10a to 10d, and the impedance between the input / output terminal 20 and the ground conductor 24 is reduced. To reactance components.

  In the linear folded antenna 100, the common mode currents I1X and I1Y act in the same manner as the current flowing through the quarter-wave antenna. Therefore, the resonant frequency at which the electrical length for the common mode currents I1X and I1Y and the antenna electrical length defined as the sum of the phase transition amounts for the common mode currents I1X and I1Y flowing in the variable capacitance diodes 14a and 14b, respectively, is π / 2. When the radio signal is input, the energy of the radiated electromagnetic wave is maximized. Conversely, in order to maximize the energy of the radiated electromagnetic wave, the common mode currents I1X and I1Y flowing through the variable capacitance diodes 14a and 14b are set so that the antenna electrical length with respect to the frequency of the input radio signal is π / 2. The amount of phase transition may be adjusted.

  The amount of phase transition with respect to common mode currents I1X and I1Y flowing through variable capacitance diodes 14a and 14b changes based on the change in capacitance of variable capacitance diodes 14a and 14b. The capacitances of the variable capacitance diodes 14a and 14b change based on the change in the voltage value of the DC voltage output from the variable DC voltage source 28. Therefore, by changing the voltage value of the DC voltage output from the variable DC voltage source 28, the resonance frequency of the linear folded antenna 100 can be adjusted, and the energy of the radiated electromagnetic wave can be maximized.

  According to the linear folded antenna 100 according to the present embodiment, the energy radiated from the antenna can be optimally adjusted over a wide frequency band of the input radio signal. Therefore, the linear folded antenna 100 is preferably applied to a wireless device that performs wireless communication in a wide frequency band. Further, the choke inductor 22 for applying the reverse bias voltage of the variable capacitance diodes 14a and 14b is provided in the vicinity of the input / output terminal 20 at a position electrically and magnetically separated from the linear conductors 10a to 10d. Can do. The distance between the anode terminal A and the cathode terminal K of the variable capacitance diodes 14a and 14b can be made sufficiently shorter than the wavelength of electromagnetic waves to be transmitted and received. For this reason, the influence of the choke inductor 22 and the variable capacitance diodes 14a and 14b on the radiation characteristics can be reduced.

  The case where the linear folded antenna 100 is operated as a transmitting antenna has been described above. The operation as a receiving antenna can be similarly explained by reversing the signal flow with respect to the operation as a transmitting antenna by the antenna reciprocity theorem. For example, the radiation directivity characteristic and the reception directivity characteristic are equal, and the linear folded antenna 100 side between the input / output terminal 20 and the ground conductor 24 when operating as a transmitting antenna and when operating as a receiving antenna. Impedances are equal. Based on this technical background, the following description will mainly describe the case where the antenna is operated as a transmission antenna.

  FIG. 3 shows the configuration of the linear folded antenna 102 according to the second embodiment of the present invention. The linear folded antenna 102 is a component configured by removing the ground conductor 24 of the linear folded antenna 100, and includes a linear conductor 10aU, a variable capacitance diode 14aU, linear conductors 10bU and 12U, a linear conductor 10cU, a variable conductor. Capacitor diode 14bU, antenna one-side element portion 32U to which linear conductor 10dU is connected, antenna one-side element portion 32W having a configuration in which the polarity of the variable-capacitance diode is reversed with respect to antenna one-side element portion 32U, input / output conductor 16U 16W, DC blocking capacitors 18U and 18W, input / output terminals 20U and 20W, choke inductors 22U and 22W, and a variable DC voltage source 28. The same components as those of the linear folded antenna 100 of FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted. However, “U” is added to the end of the reference numerals of the constituent parts belonging to the antenna one-side element part 32U, “W” is added to the reference numerals of the constituent parts belonging to the antenna one-side element part 32W, and the antenna one-side elements are added. It is to be distinguished whether the component belongs to the unit 32U or 32W.

  The length LdU of the linear conductor 10dU is shorter than the length of the linear conductor 10aU. The length LdW of the linear conductor 10dW is shorter than the length of the linear conductor 10aW. As a result, the input / output conductors 16U and 16W can be arranged separately.

  The antenna one-side element portion 32U and the antenna one-side element portion 32W are connected at the end T1U of the linear conductor 10aU and the end T1W of the linear conductor 10aW. The linear folded antenna 102 has a plane-symmetric configuration with respect to a plane including the ends T1U and T1W perpendicular to the extending direction of the linear conductors 10aU and 10aW. However, the variable capacitance diodes 14aU and 14aW and the variable capacitance diodes 14bU and 14bW are not symmetrical with respect to the plane, and are attached in directions opposite to each other. That is, the anode terminal A and the cathode terminal K of the variable capacitance diode 14aU are connected to the end T2U of the linear conductor 10aU and the end T3U of the linear conductor 10bU, respectively, and the end T6U of the linear conductor 10cU and the end of the linear conductor 10dU are connected. The anode terminal A and cathode terminal K of the variable capacitance diode 14bU are connected to T7U, respectively, while the end T2W of the linear conductor 10aW and the end T3W of the linear conductor 10bW are respectively connected to the cathode terminal K and anode of the variable capacitance diode 14aW. Terminal A is connected, and cathode terminal K and anode terminal A of variable capacitance diode 14bW are connected to end T6W of linear conductor 10cW and end T7W of linear conductor 10dW, respectively.

  An input / output conductor 16U is connected to the end T8U of the linear conductor 10dU. A choke inductor 22U and a DC blocking capacitor 18U are connected to the input / output conductor 16U. An input / output terminal 20U is connected to a terminal of the DC blocking capacitor 18U that is not connected to the input / output lead 16U. An input / output conductor 16W is connected to the end T8W of the linear conductor 10dW. A choke inductor 22W and a DC blocking capacitor 18W are connected to the input / output conductor 16W. The input / output terminal 20W is connected to the terminal of the DC blocking capacitor 18W on the side not connected to the input / output conducting wire 16W. A variable DC voltage source 28 is connected between a terminal of the choke inductor 22U that is not connected to the input / output conductor 16U and a terminal of the choke inductor 22W that is not connected to the input / output conductor 16W.

  Variable DC voltage source 28 applies a DC voltage between end T8U and end T8W via choke inductors 22U and 22W and input / output conductors 16U and 16W. The polarity of the DC voltage is positive on the choke inductor 22U side. Thus, a reverse bias DC voltage is applied to the variable capacitance diodes 14aU, 14bU, 14aW and 14bW. The variable capacitance diodes 14aU, 14bU, 14aW, and 14bW have a capacity according to the DC voltage.

  A radio signal is input as a balanced mode signal between the input / output terminal 20U and the input / output terminal 20W. Here, the balanced mode signal generally refers to a signal having a transmission form for transmitting between a plurality of line conductors that provide a signal potential, provided separately from a conductor that provides a ground potential. The radio signal is transmitted between terminals T8U and T8W via DC blocking capacitors 18U and 18W and input / output conductors 16U and 16W, and current Iin flows through terminals T8U and T8W based on the radio signal.

  The current Iin causes a common mode current I1X to flow through the linear conductors 10aU, 10bU, 10aW, and 10bW and the variable capacitance diodes 14aU and 14aW, and the linear conductors 10dU, 10cU, 10dW, and 10cW and the variable capacitance diodes 14bU and 14bW. Through which a common mode current I1Y flows.

  In the linear folded antenna 102, the common mode currents I1X and I1Y act equally as currents flowing through the half-wave antenna. Therefore, the electrical length for the common mode current I1X in the linear conductors 10aU and 10bU, the common mode current I1Y in the linear conductors 10cU and 10dU, and the phase shift amount for the common mode currents I1X and I1Y flowing in the variable capacitance diodes 14aU and 14bU, respectively. When a radio signal having a resonance frequency at which the antenna electrical length is π / 2 is input, the energy of the radiated electromagnetic wave is maximized.

  In addition, due to the symmetry of the linear folded antenna 102, the electrical length for the common mode current I1X in the linear conductors 10aW and 10bW and the common mode current I1Y in the linear conductors 10cW and 10dW, and the variable capacitance diode 14aW and The sum of the phase shift amount with respect to the common mode currents I1X and I1Y flowing through 14bW is also π / 2.

  Based on the same principle as the linear folded antenna 100 according to the first embodiment, the linear folded antenna 102 also adjusts the resonance frequency by changing the voltage value of the DC voltage output from the variable DC voltage source 28, The energy of electromagnetic waves transmitted and received can be maximized.

  The linear folded antenna 102 has a configuration in which the antenna one-side element portions 32U and 32W are arranged in plane symmetry. In addition to such a configuration, an array antenna can be configured by arranging a plurality of antenna one-side element portions at a predetermined interval.

  FIG. 4 shows the configuration of the helical folded antenna 104 according to the third embodiment. The helical folded antenna 104 is obtained by replacing the linear conductors 10a to 10d constituting the linear folded antenna 100 according to the first embodiment with helical helical inductors 34a to 34d, respectively. The same components as those of the linear folded antenna 100 are denoted by the same reference numerals and description thereof is omitted.

  The helical inductors 34a to 34d are preferably formed of metal wires, and lead parts having metal wires as the anode terminal A and the cathode terminal K are preferably applied to the variable capacitance diodes 14a and 14b. By connecting the ground conductor 24, the helical inductor 34a, the variable capacitance diode 14a, the helical inductor 34b, the linear conductor 12, the helical inductor 34c, the variable capacitance diode 14b, and the helical inductor 34d by soldering or the like, sufficient mechanical strength can be obtained. Thus, the helical folded antenna 104 can be configured. Further, the helical inductor 34a, the variable capacitance diode 14a, the helical inductor 34b, the linear conductor 12, the helical inductor 34c, the variable capacitance diode 14b, and the helical inductor 34d can be molded with a dielectric or the like to increase the mechanical strength. .

  The terminal H1 of the helical inductor 34a is connected to the ground conductor 24. A terminal H2 of the helical inductor 34a opposite to the terminal H1 is connected to the anode terminal A of the variable capacitance diode 14a. The cathode terminal K of the variable capacitance diode 14a is connected to the terminal H3 of the helical inductor 34b. The terminal H4 of the helical inductor 34b opposite to the terminal H3 is connected to the terminal H5 of the helical inductor 34c through the linear conductor 12. A terminal H6 of the helical inductor 34c opposite to the terminal H5 is connected to the anode terminal A of the variable capacitance diode 14b. The cathode terminal K of the variable capacitance diode 14b is connected to the terminal H7 of the helical inductor 34d.

  The input / output conductor 16 is connected to the terminal H8 of the helical inductor 34d on the side opposite to the terminal H7. A choke inductor 22 and a DC blocking capacitor 18 are connected to the input / output conductor 16. A variable DC voltage source 28 is connected between the terminal of the choke inductor 22 that is not connected to the input / output conductor 16 and the ground conductor 24. An input / output terminal 20 is connected to a terminal of the DC blocking capacitor 18 that is not connected to the input / output conductor 16.

  The inductance values of the helical inductors 34a to 34d are determined so that the reactance values of the helical inductors 34a to 34d are equal to the reactance values of the linear conductors 10a to 10d, respectively. The reactance values of the linear conductors 10a to 10d are determined by their electrical lengths.

  According to such a configuration, the helical inductors 34a to 34d act as elements constituting the antenna, similarly to the linear conductors 10a to 10d. Since the helical inductor is smaller than the linear conductor, the helical folded antenna 104 can be reduced in size as compared with the linear folded antenna 100.

  Based on the same principle as the linear folded antenna 100 according to the first embodiment, the helical folded antenna 104 also adjusts the resonance frequency by changing the voltage value of the DC voltage output from the variable DC voltage source 28, and transmits and receives The energy of the electromagnetic wave that is generated can be maximized.

  FIG. 5 shows a configuration of the double helical folded antenna 106 according to the fourth embodiment. The double helical folded antenna 106 is obtained by replacing the linear conductors 10a to 10d constituting the linear folded antenna 100 according to the first embodiment with spiral conductors 36a to 36d, respectively. However, a ground conductor 38 for connecting the spiral conductor 36a and the ground conductor 24 is further provided. The same components as those of the linear folded antenna 100 are denoted by the same reference numerals and description thereof is omitted. The spiral conductors 36a and 36d form a double spiral structure with a distance such that they are electrically and magnetically coupled. Further, the spiral conductors 36b and 36c form a double spiral structure with a distance such that they are electrically and magnetically coupled.

  The spiral conductors 36a to 36d and the ground conductor 38 are preferably formed of metal wires, and lead parts having metal wires as the anode terminal A and the cathode terminal K are preferably applied to the variable capacitance diodes 14a and 14b. It is sufficient to connect the ground conductor 24, the ground conductor 38, the spiral conductor 36a, the variable capacitance diode 14a, the spiral conductor 36b, the linear conductor 12, the spiral conductor 36c, the variable capacitance diode 14b, and the spiral conductor 36d by soldering or the like. The double helical folded antenna 106 can be configured with a high mechanical strength. Also, the mechanical strength can be increased by molding the spiral conductor 36a, the variable capacitance diode 14a, the spiral conductor 36b, the linear conductor 12, the spiral conductor 36c, the variable capacitance diode 14b, and the spiral conductor 36d with a dielectric or the like. .

  The lengths of the spiral conductors 36a to 36d are such that the resonance frequency of the double folded antenna 106 is included in the frequency band of electromagnetic waves to be transmitted and received, and the variable range of the capacitance of the variable capacitance diode 14a and the variable range of the capacitance of the variable capacitance diode 14b. Determine with.

  The terminal P1 of the spiral conductor 36a is connected to the ground conductor 24 through the ground conductor 38. The terminal P2 of the spiral conductor 36a opposite to the terminal P1 is connected to the anode terminal A of the variable capacitance diode 14a. The cathode terminal K of the variable capacitance diode 14a is connected to the terminal P3 of the spiral conductor 34b. The terminal P4 of the spiral conductor 36b opposite to the terminal P3 is connected to the terminal P5 of the spiral conductor 36c via the linear conductor 12. The terminal P6 of the spiral conductor 36c opposite to the terminal P5 is connected to the anode terminal A of the variable capacitance diode 14b. The cathode terminal K of the variable capacitance diode 14b is connected to the terminal P7 of the spiral conductor 36d.

  The input / output conductor 16 is connected to the terminal P8 of the spiral conductor 36d on the side opposite to the terminal P7. A choke inductor 22 and a DC blocking capacitor 18 are connected to the input / output conductor 16. A variable DC voltage source 28 is connected between the terminal of the choke inductor 22 that is not connected to the input / output conductor 16 and the ground conductor 24. Further, the input / output terminal 20 is connected to the terminal of the DC blocking capacitor 18 that is not connected to the input / output conductor 16.

  When a wireless signal is input as an unbalanced mode signal between the input / output terminal 20 and the ground conductor 24, a current Iin flows through the terminal H8 based on the wireless signal. Due to the current Iin, the common mode current I1X flows through the spiral conductors 36a and 36b and the variable capacitance diode 14a, and the common mode current I1Y flows through the spiral conductors 36c and 36d and the variable capacitance diode 14b.

  In the double helical folded antenna 106, common mode currents I1X and I1Y distributed in a spiral shape act as antennas. Therefore, when a radio signal having a resonance frequency of the winding element having the same shape as the spiral common mode current distribution is input, the energy of the radiated electromagnetic wave is maximized.

  With this configuration, the double helical folded antenna 106 can be reduced in size as compared with the linear folded antenna 100. Based on the same principle as that of the linear folded antenna 100, the double helical folded antenna 106 also adjusts the resonance frequency by changing the voltage value of the DC voltage output from the variable DC voltage source 28, and transmits and receives energy of electromagnetic waves. Can be maximized.

  Here, as the helical folded antenna 104 and the double helical folded antenna 106, a configuration (so-called monopole type) that inputs and outputs unbalanced mode signals and radiates and receives electromagnetic waves on the surface S side of the ground conductor 24. explained. However, in these antennas, similarly to the linear folded antenna 102 according to the second embodiment, the ground conductor 24 is removed by reversing the polarity of the variable capacitance diode on the opposite side and the symmetric structure with respect to the plane S. A configuration for inputting a signal (so-called dipole type) can also be used.

  That is, the linear conductors 10aU to 10dU and 10aW to 10dW constituting the linear folded antenna 102 according to the second embodiment can be replaced with helical inductors similar to the helical inductors 34a to 34d, respectively. Further, the linear conductors 10aU to 10dU and 10aW to 10dW constituting the linear folded antenna 102 according to the second embodiment can be replaced with spiral conductors similar to the spiral conductors 36a to 36d, respectively.

1 is a perspective view of a linear folded antenna according to a first embodiment. It is a side view of the linear return | turnback antenna which concerns on 1st Embodiment, and the figure which shows the structure. It is a figure which shows the structure of the linear return | turnback antenna which concerns on 2nd Embodiment. It is a figure which shows the structure of the helical return antenna which concerns on 3rd Embodiment. It is a figure which shows the structure of the double helical folding antenna which concerns on 4th Embodiment. It is a figure which shows the structure of a folding antenna.

Explanation of symbols

  10a to 10d, 12 linear conductors, 14a, 14b variable capacitance diodes, 16, 16U, 16W input / output conductors, 18, 18U, 18W DC blocking capacitors, 20, 20U, 20W input / output terminals, 22, 22U, 22W choke inductors , 24 Ground conductor, 26a, 26b Connection tube, 28 Variable DC voltage source, 30 Input / output hole, 32U, 32W Antenna one side element part, 34a-34d Helical inductor, 36a-36d Spiral conductor, 38 Ground conductor, 100, 102 linear folded antenna, 104 helical folded antenna, 106 double helical folded antenna.

Claims (12)

A first antenna element comprising two connecting ends;
A second antenna element arranged to be electrically and magnetically coupled to the first antenna element and comprising two connecting ends;
With
One connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected,
Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is an input / output end.
Of the two connection ends provided in the second antenna element, a folded antenna device in which a connection end that is not connected to one of the two connection ends provided in the first antenna element is connected to a ground conductor. ,
The first antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the first antenna element,
The second antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the second antenna element,
Between the input / output end and the ground conductor, the antenna input / output end of the folded antenna device ,
The folded antenna device is
A choke inductor connected to the input / output terminal;
The capacitance of the variable capacitance element included in the first antenna element and the second antenna are changed by changing a voltage applied between the terminal of the choke inductor on the side not connected to the input / output terminal and the ground conductor. A folded antenna device characterized in that the capacitance of a variable capacitance element included in the element can be adjusted . A first antenna element comprising two connecting ends;
A second antenna element arranged to be electrically and magnetically coupled to the first antenna element and comprising two connecting ends;
With
One connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected,
Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is defined as an input / output end, and the second antenna element is The antenna one side part which makes the connection end which is not connected to one of the two connection ends with which the said 1st antenna element is provided among two connection ends with which it is provided as a common connection end,
With two,
The two antenna one side portions are folded antenna devices connected at the common connection end provided respectively,
The first antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the first antenna element,
The second antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the second antenna element,
The input / output end provided in each of the two antenna one side portions is an antenna input / output end of the folded antenna device ,
The folded antenna device is
A first choke inductor connected to one of the two input / output terminals of the antenna input / output terminal;
A second choke inductor connected to an input / output terminal to which the first choke inductor is not connected, of the two input / output terminals of the antenna input / output terminal;
With
By changing a voltage applied between a terminal not connected to the antenna input / output terminal of the first choke inductor and a terminal not connected to the antenna input / output terminal of the second choke inductor, A folded antenna apparatus, wherein the capacitance of a variable capacitance element included in one antenna element and the capacitance of a variable capacitance element included in the second antenna element can be adjusted . A first antenna element comprising two connecting ends;
A second antenna element arranged to be electrically and magnetically coupled to the first antenna element and comprising two connecting ends;
With
One connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected,
Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is an input / output end.
Of the two connection ends provided in the second antenna element, a folded antenna device in which a connection end that is not connected to one of the two connection ends provided in the first antenna element is connected to a ground conductor. ,
The first antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the first antenna element,
The second antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the second antenna element,
Between the input / output end and the ground conductor, the antenna input / output end of the folded antenna device ,
By changing the capacitance of the variable capacitance element included in each of the first antenna element and the second antenna element, both the current flowing in the first antenna element and the current flowing in the second antenna element are changed. A folded antenna device characterized in that a resonance frequency based thereon can be adjusted . The folded antenna device according to claim 3 ,
A choke inductor connected to the input / output terminal;
The capacitance of the variable capacitance element included in the first antenna element and the second antenna are changed by changing a voltage applied between the terminal of the choke inductor on the side not connected to the input / output terminal and the ground conductor. A folded antenna device characterized in that the capacitance of a variable capacitance element included in the element can be adjusted. A first antenna element comprising two connecting ends;
A second antenna element arranged to be electrically and magnetically coupled to the first antenna element and comprising two connecting ends;
With
One connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected,
Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is defined as an input / output end, and the second antenna element is The antenna one side part which makes the connection end which is not connected to one of the two connection ends with which the said 1st antenna element is provided among two connection ends with which it is provided as a common connection end,
With two,
The two antenna one side portions are folded antenna devices connected at the common connection end provided respectively,
The first antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the first antenna element,
The second antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the second antenna element,
The input / output end provided in each of the two antenna one side portions is an antenna input / output end of the folded antenna device ,
By changing the capacitance of the variable capacitance element included in each of the first antenna element and the second antenna element, both the current flowing in the first antenna element and the current flowing in the second antenna element are changed. A folded antenna device characterized in that a resonance frequency based thereon can be adjusted . The folded antenna device according to claim 5 ,
A first choke inductor connected to one of the two input / output terminals of the antenna input / output terminal;
A second choke inductor connected to an input / output terminal to which the first choke inductor is not connected, of the two input / output terminals of the antenna input / output terminal;
With
By changing a voltage applied between a terminal not connected to the antenna input / output terminal of the first choke inductor and a terminal not connected to the antenna input / output terminal of the second choke inductor, A folded antenna apparatus, wherein the capacitance of a variable capacitance element included in one antenna element and the capacitance of a variable capacitance element included in the second antenna element can be adjusted. The folded antenna device according to any one of claims 1 to 6 ,
The folded antenna device, wherein the element elements constituting the first antenna element and the element elements constituting the second antenna element are constituted by linear conductors. The folded antenna device according to claim 7 ,
The folded antenna device, wherein the element element constituting the first antenna element and the element element constituting the second antenna element are arranged in parallel to each other. A first antenna element comprising two connecting ends;
A second antenna element arranged to be electrically and magnetically coupled to the first antenna element and comprising two connecting ends;
With
One connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected,
Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is an input / output end.
Of the two connection ends provided in the second antenna element, a folded antenna device in which a connection end that is not connected to one of the two connection ends provided in the first antenna element is connected to a ground conductor. ,
The first antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the first antenna element,
The second antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the second antenna element,
Between the input / output end and the ground conductor, the antenna input / output end of the folded antenna device ,
The folded antenna device, wherein the element elements constituting the first antenna element and the element elements constituting the second antenna element are constituted by a spiral inductor . A first antenna element comprising two connecting ends;
A second antenna element arranged to be electrically and magnetically coupled to the first antenna element and comprising two connecting ends;
With
One connection end of the two connection ends included in the first antenna element and one connection end of the two connection ends included in the second antenna element are connected,
Of the two connection ends included in the first antenna element, a connection end that is not connected to one of the two connection ends included in the second antenna element is defined as an input / output end, and the second antenna element is The antenna one side part which makes the connection end which is not connected to one of the two connection ends with which the said 1st antenna element is provided among two connection ends with which it is provided as a common connection end,
With two,
The two antenna one side portions are folded antenna devices connected at the common connection end provided respectively,
The first antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the first antenna element,
The second antenna element is
A variable capacitance element whose capacitance changes according to an applied voltage;
An element element connected to the variable capacitance element and constituting the second antenna element,
The input / output end provided in each of the two antenna one side portions is an antenna input / output end of the folded antenna device ,
The folded antenna device, wherein the element elements constituting the first antenna element and the element elements constituting the second antenna element are constituted by a spiral inductor . The folded antenna device according to claim 9 , wherein
A choke inductor connected to the input / output terminal;
The capacitance of the variable capacitance element included in the first antenna element and the second antenna are changed by changing a voltage applied between the terminal of the choke inductor on the side not connected to the input / output terminal and the ground conductor. A folded antenna device characterized in that the capacitance of a variable capacitance element included in the element can be adjusted. The folded antenna device according to claim 10 , wherein
A first choke inductor connected to one of the two input / output terminals of the antenna input / output terminal;
A second choke inductor connected to an input / output terminal to which the first choke inductor is not connected, of the two input / output terminals of the antenna input / output terminal;
With
By changing a voltage applied between a terminal not connected to the antenna input / output terminal of the first choke inductor and a terminal not connected to the antenna input / output terminal of the second choke inductor, A folded antenna apparatus, wherein the capacitance of a variable capacitance element included in one antenna element and the capacitance of a variable capacitance element included in the second antenna element can be adjusted.

Images