JPS61125204A - Multi-frequency shared antenna - Google Patents

Abstract

PURPOSE:To realize a rod antenna with a wide band and plural resonance frequency bands by adding a coil of a required number of turns to a tip of a wire antenna element so as to flow a current reversely to a current flowing to the element. CONSTITUTION:The antenna is formed with a lambda/4 length cylindrical negative pole antenna element 1, a lambda/4 length positive pole element 2 and a coaxial feeder 3, and the coil 4 having a prescribed number of turns and diameter is fitted to the tip so as to take the tip of the positive antenna element 2 as its center. In measuring the characteristic of a sleeve antenna with parameters of, e.g., nearly 1.87m of the element length of the positive and negative pole antennas, 10mm in diameter and tight winding as the coil with the height (l)=100mm, the 1st resonance point is obtained at 40MHz as shown in figure. Further, the 2nd resonance point is produced at a point lower than the 1st point by 5MHz, that is, at 35MHz, resulting that the two resonance points are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-frequency shared antenna device, and particularly to an antenna device ftK having a plurality of resonance bands.

[Prior art] In general, a linear antenna is used by resonating with the wavelength used, and this resonance occurs when the length of the antenna element is approximately equal to the wavelength λ.
(lambda) occurs at 1/2 or le/2 (le is an integer). Furthermore, the range in which such resonance can be obtained is generally limited to within the vicinity of the center frequency, and the applicable wave number band of one linear antenna is extremely narrow, being several percent of the center frequency used.

Furthermore, the resonant frequency band obtained by the main antenna is usually one, and if it is used at a frequency exceeding this range, not only will the antenna efficiency drop significantly, but the matching between the transmitter and the receiver will shift and the transmitter will not be able to transmit. There is even a risk of damaging the machine's power amplifier circuit.

Conventionally, various countermeasures have been devised for this purpose, and an example of this will be explained below regarding a sleeve antenna.

That is, FIG. 6 is a diagram schematically showing the structure of a conventional sleeve O antenna, in which a positive electrode element 2 having a length of λ/4 is placed on the central axis of the head ff1tflll of a cylindrical negative element 1 having a length of λ/4. In addition to erecting and insulating each other to form an antenna, power is supplied to both antenna elements via a coaxial reduced-feed m line 3 that passes through the cylindrical negative electrode antenna element 1. It will be carried out in .

The feature of this sleeve antenna is that two parallel lines newly formed by the cylindrical negative electrode element 1 and the jacket conductor of the coaxial feed line 3 passing through it are connected to the cylindrical negative electrode element. Since the impedance seen from the lower end opening becomes extremely large, the flow of unstable current induced from the antenna element into the external body of the coaxial feed 1113 connected to this antenna is prevented, thereby stabilizing the operation of the antenna. It is something that forces you to do something.

The above-mentioned method for widening the band using such a sleeve antenna is @old! By increasing the cylindrical diameter of the two negative electrode elements l, the impedance is increased, thereby somewhat expanding the usable frequency band.

In addition to widening the applicable band, in order to use it in multiple bands, for example, insert an adjustable inductance in the middle of the antenna element and change it according to the frequency of use to adjust the electric power of the element. It is possible to adjust the length. In this case, the inductance is adjusted automatically by adjusting the transmission signal power to the antenna, for example, by adjusting the amount of reflection of the feeding current, or by tuning means in conjunction with a channel changeover switch.

[Problems to be Solved by the Invention] However, it is difficult to say that any of the conventional methods of widening the band of an antenna as described above are atrocities. In other words, the former method of widening the band naturally has its limitations in terms of the size of the scale and antenna, as well as the thickness of the antenna.

In addition, the latter method requires a complicated device and requires only a single piece of equipment, making it difficult to use either method as a portable antenna. Historically, no conventional antenna had a resonant frequency in the same wave number band of different sides.

[Means and operations for solving the problem] The present invention is based on a completely different principle from the conventional method of widening the band of a linear antenna as described above, and is based on a U-shaped method that neglects a wide band and multiple resonant frequency bands. The purpose is to provide an antenna.

In order to achieve this objective, the present invention takes the following measures: ◎ That is, a coil is added to the tip of the linear antenna so that it flows in the opposite direction to the direction of the high wave current flowing through this antenna, The coil is configured so that the relationship between the inductance and the frequency is as required.

Although the exact operation of the antenna constructed in this manner is unknown, the effect of the coil attached to the tip is estimated as follows.

A coil of a desired diameter and number of turns is positioned at the tip of a conventional linear antenna, such as a sleeve-type antenna, with the tip of the positive element of the sleeve antenna as the central axis,
The upper end of the coil and the front ll! An antenna connected to the tip of the positive electrode element, that is, the positive electrode element wraps around the element from its tip (considering an antenna with a hanging coil added). Similarly, a first resonance point is obtained that resonates with the length of the antenna element. At this time, since the coil hangs in the opposite direction to the extension direction of the antenna element, the current direction of both is opposite, which is similar to the conventional sleeve antenna. It is thought that the effect is different from that of simply adding a coil to the tip of the element in the direction in which the element extends.

The reason why it is possible to have the same resonant frequency as a conventional sleeve antenna despite the addition of a coil is because there is a floating distance of 61 m between this coil and the tip of the antenna element to which it is attached, and this capacitance. , the inductance of the coil itself, and K form a parallel resonant U path, and this parallel circuit resonates in parallel with the resonant frequency when no U-path is attached, exhibiting high impedance and the same first antenna as the conventional antenna. It has a resonance point of 5 more
When the applied wavenumber is reduced, the parallel circuit deviates from the parallel resonance point and simply acts as an inductance, with tI3 determined by the vertical and inner diameter dimensions of the coil.
It is presumed that second resonance points can be obtained at eleven positions.

〔Example〕

The present invention will now be described in detail based on illustrative embodiment V.

FIG. 1 is an external view showing an embodiment of a 4 Q MHz borrowed sleeve antenna to which the present invention is applied. In the same figure, 1 is a λ/4 long cylindrical negative pole antenna element, 4 respectively show a λ/4 length positive element and a coaxial feeder, and a coil 4 with a predetermined number of turns and diameter is connected to a pole centering on the tip of the positive antenna Q element 2. <It is attached to the tip.

If we specifically state the value of each purple sweet potato at this time, the length of the positive and negative antenna elements is approximately 1.8771t.

The coil has a diameter of Class 10, is tightly wound, and the normal dimension of the coil at this time is l = 100 m. When the characteristics of the sleeve antenna constructed in this manner were measured, the results shown in FIG. 2 were obtained.

As is clear from the figure, the first resonance point is obtained at 4QMHz. This is the same resonant frequency as the conventional antenna, and shows that the 4V MfJ g picoil added in the present invention does not change the resonant frequency. Also, the point 5MH2 lower from this point, that is, 35 MH
2, a second resonance point is produced, resulting in two co-fluorescent points.

Therefore, the antenna can be used in two frequency bands with center frequencies of 4 Q MHz and 35 MH2.

Such an antenna is optimal for a duplex system that uses two frequencies, 4Q MHz and 35 MHz, for transmission and reception, and the present invention can be applied to antennas that conventionally used separate antennas for transmission and reception. This makes it very interesting to be able to stand next to each other with just one antenna.

For reference, as shown in Fig. 3, we will consider the frequency temporality when the above-mentioned coil 4 is simply added to the tip of the antenna element so as to extend it. Although not shown in the figure, the resonance at this time [ 7) The antenna has only one frequency lower than the resonant frequency of a conventional sleeve antenna, that is, one without a coil, and its standing wave ratio is inferior to that of the conventional sleeve antenna.

As is clear from the comparison between the two, although both have the same coil attached to the end of the antenna element, it can be seen that the coil attachment exhibits completely different phenomena depending on the direction. Since the second resonance frequency can be arbitrarily selected by varying the number of turns of the coil 4 and its diameter, it may be set as appropriate depending on the purpose of use.

For example, the vertical dimension of the cut coil 4 is 95mVC5am.
It has been confirmed that the second resonant frequency becomes 35.5 MHz and shifts to 0.5 MHz.

On the other hand, although the above embodiment shows a case in which a coil is added to a sleeve antenna, the present invention is not limited to this in any way and can be applied to all kinds of linear antennas.

In addition, a sleeve antenna with 9 ports (not only for vertically polarized waves but also for horizontally polarized waves such as a divolute antenna) is also applicable.

That is, FIG. 4 is a schematic diagram of an antenna device showing another embodiment of the present invention, and FIG. FIG. 3(b) shows an H-type antenna with a coil 4 added to the tip of the positive element.

With this configuration, it is possible to make a dipole antenna and an h-type antenna each having two common regions similar to My described above.

The coil 4 may be attached to any structure, but in consideration of the installation strength, for example, the tip of the antenna element 7 may be attached as shown in FIG. 5(a). It is inserted into an insulating material pipe 8 such as a dielectric material, and a steel wire or the like is wound around the surface of the pipe to form a coil 4, and its tip #
The antenna element 9 may have a structure in which it is connected to the front 8e antenna element 7, or it may have an extension part of the antenna element element 9 itself bent and integrally molded into a coil shape as shown in FIG. 8(b). It's okay.

〔Effect of the invention〕

Since the present invention is configured and operates as described above, it is possible to realize an antenna device having a plurality of resonance points at arbitrary frequency intervals of 1'lJj with a simple configuration. It is extremely effective in making an antenna device extremely convenient as an antenna for a type wireless communication device or an antenna for a wireless communication device for multi-frequency delivery.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the sleeve antenna to which the present invention is applied, Fig. 2 is a frequency characteristic diagram of the actual example shown in Fig. 1, and Fig. 3 is a modification of the conventional sleeve antenna. A schematic diagram showing an example, and FIG. 4 shows another actual example of the present invention, in which (a) is a dipole antenna, (b) is an h
Figure 5 is a schematic diagram of the present invention applied to each type of antenna.
a) and (b) are sectional views and external views showing structural examples of the coil added in the present invention, and Fig. 6 is a conventional sleeve/sleeve.
0160. This is a structural diagram of the antenna. Positive antenna element, 2...Cylindrical negative antenna element, 3...Coaxial feed 1!1. II
i! , 4... Coil, 5, 6.7 and 9... Antenna element, 8... Dielectric (l 1 ) Figure 5 (a) (b) Figure 6:

Claims (1)

[Claims] 1. A multi-frequency antenna characterized in that a coil with a required number of turns is added to the tip of a linear antenna element so that current flows in the opposite direction to the current flowing through the element.