JP2006222737A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make various kinds of antenna elements usable, and make the antenna elements arrangeable, according to allowed space, and furthermore, to suppress harmonics generated in the transmission band. <P>SOLUTION: The antenna device divides the transmission signal into two parts, then makes each signal pass through phase-shifters 4, 5 whose phase-shift amounts are 0 [rad] and -&pi; [rad], and feeding lines 6, 7 whose electrical lengths are L [m] (L is arbitrary) and L+&pi;&lambda;(f) [m] (here, f is the frequency of the transmission signal, &lambda;(f) indicates the wavelength of the transmission signal of frequency f), makes the transmission signals from two antenna elements 8, 9 combine spatially, and transmits. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to an antenna device that transmits broadband radio waves and suppresses transmission of unnecessary harmonics in a transmission signal.

  As an antenna device that transmits broadband radio waves and suppresses transmission of unnecessary harmonics in a transmission signal, an antenna device as shown in Japanese Patent Laid-Open No. 11-308047 (see Patent Document 1) has been known. FIG. 4 shows the configuration of a conventional antenna device that suppresses such harmonics. The antenna element 19 and the antenna element 20 are arranged so as to be orthogonal to each other, and the antenna element 19A and the antenna element 20A are orthogonal to each other. The phase shifter 18 is provided for each element antenna, and by setting the phase of each element antenna, the seed signal is combined with the horizontally polarized wave, and the harmonics are canceled in the opposite phase.

JP-A-11-308047

  However, in the conventional antenna device that suppresses such harmonics, when the frequency that is twice the lower limit frequency of the transmission signal is lower than the upper limit frequency of the transmission band, it is not possible to suppress the harmonics that occur in the transmission band. There was a problem. In addition, antenna elements that transmit a transmission signal to space are limited to linearly polarized antenna elements having a pattern formed on a printed circuit board, and there is a problem that the degree of freedom in selecting antenna elements is small. Furthermore, it is necessary to arrange the printed circuit boards so as to be orthogonal to each other by making a notch in the center of the printed circuit board.

  The present invention is to solve the above-described problems. In an array antenna apparatus that transmits broadband radio waves, after the transmission signal is divided into two, the phase shift amounts are 0 [rad] and −π [rad], respectively. ], And electrical lengths L [m] (L is arbitrary) and L + π · λ (f) [m] (f is the frequency of the transmission signal, λ (f) is the wavelength of the transmission signal of frequency f), respectively. The transmission signals are passed through the two antenna elements and transmitted from the two antenna elements by spatial synthesis.

According to the present invention, the phase of the signal transmitted from the two antenna elements can be made to be equal in phase with the fundamental wave of frequency f and opposite in phase with the second harmonic of frequency 2f. Transmission of unnecessary second harmonics in the signal can be suppressed. Further, there are fewer restrictions on the types and arrangement of antenna elements than in the conventional example, and various types of antenna elements can suppress the above harmonics by arranging the antennas according to the allowable space.

Embodiment 1.
The configuration of the first embodiment of the present invention will be described with reference to FIG. 1 is a transmission signal generator that generates a transmission signal, 2 is an amplifier that amplifies the generated transmission signal, 3 is a distributor that distributes the amplified transmission signal to the first and second paths, and 4 is a distributed first A first phase shifter of phase shift amount φ1 that controls the phase of the signal of the first path, and a second phase shifter of phase shift amount φ2 that controls the phase of the signal of the distributed second path, 6 is a first feed line of electrical length L1 that feeds the signal of the phase-controlled first path; 7 is a second feed line of electrical length L2 that feeds the signal of the phase-controlled second path; Reference numeral 8 denotes a first antenna element that transmits a fed first path signal to the space, and reference numeral 9 denotes a second antenna element that radiates the fed second path signal to the space.

  Next, the operation in the first embodiment of the present invention will be described. The transmission signal generated by the transmission signal generator 1 is amplified by the amplifier 2 and supplied to the distributor 3. The phase of the transmission signal distributed by the distributor 3 and fed to the first path is controlled by the first phase shifter 4 with the phase shift amount φ1. At this time, φ1 = 0 [rad] is controlled. The transmission signal distributed by the distributor 3 and fed to the second path is phase-controlled by the second phase shifter 5 with the phase shift amount φ2. At this time, control is performed to φ2 = −π [rad].

  The transmission signal whose phase is controlled by the first phase shifter 4 is fed to the first feed line 6 having the electrical length L1. At this time, the electrical length L1 of the first feeder line 6 is L [m]. The transmission signal whose phase is controlled by the second phase shifter 5 is fed to the second feed line 7 having the electrical length L2. At this time, the electrical length of the second feed line 7 is L2 = L + π · λ (f) [m]. Here, f is the frequency of the transmission signal, and λ (f) is the wavelength of the transmission signal of frequency f. The transmission signal output from the first feeder line 6 is transmitted from the first antenna element 8 to the space. The transmission signal output from the second feeder line 7 is transmitted from the second antenna element 9 to the space.

Next, the principle of suppressing the second harmonic in the transmission signal when transmitting a transmission signal of frequency f will be described.
The phase of the transmission signal at the output terminal of the first path of the distributor 3 and phi _A1.
The phase of the transmission signal at the output end of the second path of the distributor 3 is assumed to be _φA2 .
The transmission phase of the first phase shifter 4 of output signal and phi _B1.
The transmission phase of the second output terminal of the signal of the phase shifter 5 and phi _B2.
The transmission phase of the signal at the output end of the first feed line 6 is φ _C1 .
The transmission phase of the output terminal of the signal of the second feed line 7 and phi _C2.

First, in the fundamental wave (frequency f),
Since the phase of the transmission signal is the same between the path 1 and the path 2 at the output terminal of the distributor 3, it is assumed as follows.
φ _A1 = φ ₁
φ _A2 = φ ₁
Since the phase shift amount of the first phase shifter 4 is 0 [rad] and the phase shift amount of the second phase shifter 5 is −π [rad], the first phase shifter 4 and the second phase shifter 4. The phase of the transmission signal at the output terminal of the phase shifter 5 is as follows.
φ _B1 = φ ₁
φ _B2 = φ ₁ −π

Since the electrical length L1 of the first feed line 6 is L [m] and the electrical length L2 of the second feed line 7 is L + π · λ (f) [m], the first feed line 6 and the second feed line 6 The phase of the transmission signal at the output end of the feeder line 7 is as follows.
φ _C1 = φ ₁ + L / λ (f)
φ _C2 = φ ₁ −π + (L + π · λ (f)) / λ (f)
= Φ ₁ + L / λ (f)
From the above, the fundamental wave is synthesized and transmitted to the space because the phases of the transmission signals fed to the first antenna element 8 and the second antenna element 9 are equal in phase.

Next, in the second harmonic (frequency 2f),
Since the phase of the transmission signal is the same between the path 1 and the path 2 at the output terminal of the distributor 3, it is assumed as follows.
φ _A1 = φ ₂
φ _A2 = φ ₂
Since the phase shift amount of the first phase shifter 4 is 0 [rad] and the phase shift amount of the second phase shifter 5 is −π [rad], the first phase shifter 4 and the second phase shifter 4. The phase of the transmission signal at the output terminal of the phase shifter 5 is as follows.
φ _B1 = φ ₂
φ _B2 = φ ₂ −π

Since the electrical length L1 of the first feed line 6 is L [m] and the electrical length L2 of the second feed line 7 is L + π · λ (f) [m], the first feed line 6 and the second feed line 6 The phase of the transmission signal at the output end of the feeder line 7 is as follows.
φ _C1 = φ ₂ + L / λ (2f)
= Φ ₂ + 2L / λ (f)
φ _C2 = φ ₂ −π + (L + π · λ (f)) / λ (2f)
= Φ ₂ −π + (2L + 2π · λ (f)) / λ (f)
= Φ ₂ + L / λ (f) + π
∵ λ (2f) = λ (f) / 2
From the above, the second harmonic is suppressed because the phase of the transmission signal fed to the first antenna element 8 and the second antenna element 9 is opposite.

Next, calculation examples of transmission patterns of the antenna elements 8 and 9 will be described.
Transmission signal E _A = sin (2πft−πdsinθ / λ) of the antenna element 8
Transmission signal E _B = sin (2πft + πdsinθ / λ) of the antenna element 9
Where θ is the direction of radio wave emission and the transmission pattern of the fundamental wave E1 = E _A + E _B = 2sin (2πft) cos (πdsinθ / λ)
Second harmonic transmission pattern E2 = E _A- E _B = 2cos (2πft) sin (πdsinθ / λ)
As a result of calculation by applying the following specific numerical examples to the above expressions E1 and E2, waveforms as shown in FIG. 2 were obtained.
Transmission frequency f: 1GHZ,
Transmission wavelength λ: 300mm,
Antenna element spacing d: 150mm,
Antenna element beam width θB: 60 °
As is apparent from the waveform of FIG. 2, it can be seen that the second harmonic E2 can be suppressed from 6 [dB] to 20 [dB] or more from the fundamental wave E1 in the transmission pattern.

As described above, according to Embodiment 1 of the present invention, the phases of the signals transmitted from the two antenna elements can be made equal in phase at the fundamental wave of frequency f and opposite in phase at twice the frequency 2f. It is possible to effectively suppress unnecessary double harmonics generated in a wide transmission band.
The two antenna elements for transmitting a transmission signal to space are, for example, any kind of a circularly polarized antenna element such as a spiral antenna and a linearly polarized antenna element such as an antenna having a pattern mounted on a printed circuit board. Even an antenna can suppress unnecessary second harmonic transmission in a transmission signal generated from a transmission signal generator and an amplifier, so there is no restriction on the type of antenna element, and the antenna element according to the allowable space Is possible.

Embodiment 2.
A configuration according to the second embodiment of the present invention will be described with reference to FIG. In FIG. 3, reference numerals 1 to 6 and 8 to 9 denote the same parts as those in the first embodiment. 7-1 to 7 -N are the 2-1 to 2-N feeder lines, 10 is the first switch, 11 is the second switch, 12 is the third switch, 13 is the fourth switch, 14 Is a power supply path controller.

  Next, the operation in Embodiment 2 of the present invention will be described. As in the first embodiment, the transmission signal generated by the transmission signal generator 1 is amplified by the amplifier 2 and supplied to the distributor 3. The phase of the transmission signal distributed by the distributor 3 and fed to the first path is controlled by the first phase shifter 4 with the phase shift amount φ1. At this time, φ1 = 0 [rad] is controlled. The transmission signal distributed by the distributor 3 and fed to the second path is phase-controlled by the second phase shifter 5 with the phase shift amount φ2. At this time, control is performed to φ2 = −π [rad].

The transmission signal phase-controlled by the first phase shifter 4 passes through the first switch 10 and is fed to the first feed line 6 having the electrical length L1, passes through the third switch 12, and passes through the first switch 10. 1 is transmitted from one antenna element 8 to the space. At this time, the electrical length L1 of the first feed line 6 is L [m]. On the other hand, the transmission signal whose phase is controlled by the second phase shifter 5 selects one of the 2-1 to 2-N feed lines 7-1 to 7-N by the second switch 11. Then, the power is supplied, passes through the fourth switch 13, and is transmitted from the second antenna element 9 to the space. At this time, the first switch 10 and the second switch 11 have the same transmission phase characteristics. The third switch 12 and the fourth switch 13 have the same transmission phase characteristics. The electrical lengths L2 _{1 to} L2 N of the 2-1 to 2-N feeder lines 7-1 to 7- _N are as follows.

L2 ₁ = L + π · λ (f ₁ ) [m]
L2 ₂ = L + π · λ (f ₂ ) [m]
・
・
・
L2 _N = L + π · λ (f _N ) [m]
Here, f _{1 to} f _N are the frequencies of the transmission signals, and λ (f ₁ ) to λ (f _N ) are the wavelengths of the transmission signals of the frequencies f _{1 to} f _N.

In the first embodiment, the configuration in which the transmission of the second harmonic is suppressed in the case of the single transmission frequency f is shown. However, in the second embodiment, the feeding path controller 14 transmits the transmission frequency from the transmission signal generator 1. A signal is input, the frequency closest to the transmission frequency is selected from f _{1 to} f _N , and the second switch 11 and the fourth switch 13 are controlled by the power supply path selection signal.
For example transmission frequency f if closest to f _2, selects a 2-2 feed circuit 7-2 controls the second switch 11 and fourth switch 13.
As described above, according to the second embodiment, in addition to the operation of the first embodiment, by selecting and controlling the electrical length of the feed line through which one transmission signal passes based on the transmission frequency, Even when the frequency is changed, it is possible to suppress the transmission of unnecessary second harmonics by selecting the frequency closest to the frequency, so that the versatility is improved.

  In the present invention, as described in the above embodiment, the number of antenna elements that transmit a transmission signal to space is not limited to two, and a plurality of (arbitrary number) antenna elements are arranged as one set. Even in the array antenna, the fundamental wave of the frequency f can be in the same phase, and the second harmonic of the frequency 2f can be in the opposite phase. Transmission can be suppressed.

It is a figure which shows the structure of the antenna apparatus in Embodiment 1 of this invention. It is a figure which shows the example of calculation of the transmission pattern in Embodiment 1 of this invention. It is a figure which shows the structure of the antenna apparatus in Embodiment 2 of this invention. It is a figure which shows the structure of the antenna apparatus in the prior art example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission signal generator 2 Amplifier 3 Divider 4 1st phase shifter 5 2nd phase shifter 6 1st feed line 7 2nd feed line 7-1 to 7-N 2nd-1 to 2nd -N feed line 8 first antenna element 9 second antenna element 10 first switch 11 second switch 12 third switch 13 fourth switch 14 feed path controller 15 transmission signal generator 16 amplifier 17 Distributor 18 Phase shifter 19 Antenna element 20 Antenna element 19A Antenna element 20A Antenna element

Claims (7)

  In an array antenna apparatus that transmits a broadband signal, after the transmission signal is divided into two, a phase shifter with phase shift amounts 0 [rad] and −π [rad], and an electrical length L [m] (L is (Optional) and L + π · λ (f) [m] (f is the frequency of the transmission signal, λ (f) is the wavelength of the transmission signal of frequency f), and the transmission signal is spatially synthesized from the two antenna elements. An antenna device characterized by being transmitted.   2. The transmission line according to claim 1, wherein after the transmission signal is divided into two, a feeding line through which one of the transmission signals passes is selected from a plurality of feeding lines having an electrical length based on the frequency of the transmission signal. An antenna device.   3. The antenna device according to claim 1, wherein the two antenna elements that transmit a transmission signal to space can select either a circularly polarized antenna element or a linearly polarized antenna element.   4. The antenna device according to claim 1, wherein the number of antenna elements that transmit a transmission signal to space is an array antenna in which a plurality of antenna elements are arranged as one set.   A transmission signal generator for generating a transmission signal; an amplifier for amplifying the transmission signal generated by the transmission signal generator; a distributor for distributing the transmission signal amplified by the amplifier to first and second paths; The first phase shifter with phase shift amount φ1 for controlling the phase of the signal on the first path, and the second phase shifter with phase shift amount φ2 for controlling the phase of the signal on the distributed second path , A first feed line of electrical length L [m] (L is arbitrary) for feeding a signal of the first path phase-controlled by the first phase shifter, and phase control by the second phase shifter A second feed line having an electrical length L + π · λ (f) [m] (f is the frequency of the transmission signal and λ (f) is the wavelength of the transmission signal of the frequency f) for feeding the signal of the second path that is A first antenna element that transmits a signal of the first power feed path to space, and a signal of the second power feed path is radiated to space. Antenna apparatus characterized by having a second antenna element.   6. The antenna device according to claim 5, wherein the phase shift amount φ1 is controlled to 0 [rad], and the phase shift amount φ2 is controlled to −π [rad].   6. The power supply path according to claim 5, wherein the second power supply line is composed of a plurality of power supply lines having different electrical lengths, and selects a power supply line having a frequency closest to the transmission frequency extracted from the transmission signal generator. An antenna device comprising a control means.

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