JPS6033003B2 - Log-periodic antenna for shortwave band - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in log-periodic antennas for shortwave bands.

The size of log-periodic antennas, which have conventionally been widely used for medium-to-long distance communication in the short wave band, is determined by the value of the low frequency within the frequency band used.

That is, if the length of each element 2 of the log-periodic antenna illustrated in FIG.
is determined by the following formula m.

〆． =Kyo - Consideration (adversary) -------m Karisemi Wakinada Yoryo Mine The length n of the shortest element (nth element from the longest element) is determined by the following formula [2} .

Mu = A Ding elbow (adversary) Sangei - Kamo Min (hada)... A 2-kari ruts Santo Reinashi On the other hand, the antenna length shown by L in Figure 1 is L=.

tki,. Here, Q is expressed as the angle formed by the line connecting one end of each element and the line connecting the other end, and as a result, in this type of antenna, the following relationship is established.

So. Therefore, for example, the length and the size of L in the antenna with the lowest frequency fL of 2M day 2 are twice those of the antenna with the frequency fL as 4MHZ, and therefore the former The construction area and construction cost of the latter antenna are significantly larger than those of the latter antenna.

Furthermore, when the frequency fL is set low in a log-periodic antenna having antenna elements arranged in multiple directions as illustrated in FIG. 2, problems associated with the increase in the shape are even more serious. In FIG. 2, 1 is a support column, 2 is an antenna element, 3 and 4 are insulators, 5 is an insulator for an intermediate feeder, 6 is a feed line, 7 is an impedance matching device, and 8 is a support column branch line. The antenna element 2 is supported by the feed line 6 in the manner shown in FIG. 0'.

It is the antenna element 2 that operates as a log-periodic antenna, and the support column 1 does not operate as an antenna element. Therefore, the support column 1 does not need to be electrically connected to the power supply line 6, but mechanically supports the power supply line 6. In view of the above points, the present invention provides a shortwave band log-periodic antenna that is the same size as a conventional log-periodic antenna but can cover a low frequency band that is twice as large as that of the subordinate antenna. The purpose is to

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

Note that among the symbols used in the following description, the same symbols as those shown in FIG. 2 refer to the same components. The antenna according to the present invention has a configuration as shown in FIG.

The configurations of the antenna element 2, intermediate feed section insulator 5, feed line 6, etc. are the same as in FIG. 2, but the structure of the support column 1 is different, and its main feature lies in the configuration of the support column 1 portion. That is, the antenna of the present invention, as shown enlarged in FIG.
It has a configuration in which a plurality of conductive wires 9 are suspended around the support column 1 at predetermined intervals. Specifically, each of the conductive wires 9 is connected and supported to metal fittings 10 provided at appropriate places at the top of the support 1 and in the middle thereof, and the lower ends of the conductive wires are commonly connected with an annular conductor 11 and then connected through an insulator 12. It's tied to the earth. As shown in FIG. 5, the horizontal body consisting of the above-mentioned support 1 and each conducting wire 9 has a base-grounded vertical antenna (hereinafter referred to as a first antenna) whose lower end common connection point of each conducting wire 9 is a feeding point 14. ).

In principle, this first antenna can be expressed as shown in Figure 0, and if we further divide it into a zero-phase system (Kan radiation system) and a positive phase system (non-Kan radiation system), each They can be expressed as m and N in the same figure. In addition, lr (x.) shown in the figure 0'
and 1, (x,) are the currents flowing through the support column 1 and the conductor 9, respectively, at a position x above the base of the first antenna,
In addition, kl', (x,) and 1', (x,) shown in m in the same figure are the jugular currents flowing respectively in both layers in the same layer, and lo(x,) shown in W in the same figure is the same level calendar. The positive-sequence current flowing in both is shown in . Furthermore, the current kl' shown in m in the same figure. The coefficient k of (x.) represents the ratio between the Korean current flowing through the support column 1 and the same current flowing through the conducting wire 9. As described above, the antenna of the present invention is configured such that the support column 1 portion functions independently as an antenna.

Therefore, we will temporarily change the frequency band used to 2MHZ to 3MHz.
The range of 2MHZ to 4MHZ in the band is assigned to the first antenna, and the range of 4MHZ to 30MHZ is
A log-periodic antenna (hereinafter referred to as the second antenna) consisting of the antenna element 2 and the feed line 6 whose range is shown in FIG.
This is equivalent to doubling the usable frequency band with the same dimensions as a conventional log-periodic antenna.

That is, the VSWR-frequency characteristics and the antenna gain-frequency characteristics of the conventional log-periodic antenna and the antenna of the present invention having the same size and configuration as the conventional antenna are as shown in FIGS. 6 and 7, respectively. Become. As a result, this antenna requires less land area than conventional antennas of this type with the same characteristics, and can significantly reduce construction costs. By the way, if reduced frequency power is supplied only to the first antenna as shown in Fig. 8b, the directivity of the first antenna is naturally different from the mirror directivity in the horizontal plane of the second antenna, and becomes almost omnidirectional. .

However, as illustrated in FIG. 8a, power is not directly fed to the first antenna, but low-frequency power is fed only to the second antenna, and an actance element 15 of a predetermined value is connected between the feeding point of the first antenna and the ground. When interposed, mutual inductance exists even if the first antenna and the second antenna are not directly coupled, so by adjusting the value of this element 15 and also adjusting the impedance matching device of each second antenna, , the composite Korean radiation pattern of the first antenna and the second antenna at a low frequency within the used frequency band can be approximately a unidirectional pattern. In addition, as exemplified in FIG. The relationship between the current ILP that supplies power to the first antenna through the antenna and flows into the second antenna, and the current lv that flows into the first antenna, l
By adjusting lv/ILPI=Q and the phase difference angle 8 between the two military streams ILP and lv using the phase adjuster 18, the combined radiation pattern of both antennas can be made unidirectional.

As described above, according to the configurations shown in FIGS. 8a and 9, a unidirectional Korean radiation pattern in the low frequency band can be obtained, so that the antenna functions as a more effective antenna.

In addition to the embodiment shown in Fig. 4, the above-mentioned first antenna is
It can be configured as shown in FIGS. 0 and 11. The embodiment shown in FIG. 10 is based on the intermediate metal fitting 1 in FIG.
0, and with this configuration, the VSWR-frequency characteristics can be further improved. Furthermore, in the embodiment shown in FIG. 11, a so-called self-supporting steel tower that does not use branch wires is used as the support column 1, and in this case as well, polygonal metal fittings 10' are used to connect an appropriate number of conductive wires 9 around the steel tower 1. Expand this book. Of course, the lower ends of each conductive wire 9 are connected in common while being insulated from the ground, and this connection point is defined as a feeding point 14. In each of the above-mentioned embodiments, a plurality of conductive wires 9 are suspended around a support column or a steel tower, but it is of course possible to implement the present invention even if the number of conductive wires 9 is only one.

Further, the conducting wire 9 does not necessarily need to be suspended from the top of the support column 1. That is, the antenna of the present invention functions satisfactorily even if the conducting wire 9 is suspended from the metal fitting 10 provided in the middle of the support column. However, if the supporting column 1 is surrounded by a conducting wire as in the above embodiment, the diameter of the upper portion of the supporting column will be substantially increased, so that it functions as a better antenna. As described above, according to the present invention, it is possible to more than double the characteristics of a log-periodic antenna in the low frequency band with a relatively simple configuration. A band log-periodic antenna can be provided.

[Brief Description of the Drawings] Fig. 1 is a conceptual diagram showing a basic configuration example of a log-periodic antenna, Fig. 2 is a conceptual diagram of a conventional multidirectional log-periodic antenna,
Fig. 3 is a conceptual diagram showing an embodiment of the present invention, Fig. 4 is a conceptual diagram showing an enlarged support portion in Fig. 3, and Fig. 5 shows the operating principle of the antenna with the configuration shown in Fig. 4. Figure 6 is a graph showing VSWR vs. frequency characteristics and antenna gain vs. frequency characteristics of a conventional log-periodic antenna, and FIG. 7 is a graph showing VSWR vs. frequency characteristics and antenna gain vs. frequency characteristics of the antenna of the present invention. A graph showing an example,
8a, 8b and 9 are conceptual diagrams partially showing other embodiments of the present invention, FIG. 10 is a conceptual diagram showing another example of the configuration of FIG. 3, FIG. 11 is a conceptual diagram showing another embodiment of the present invention using a freestanding steel tower as a support column. DESCRIPTION OF SYMBOLS 1... Support column, 2... Antenna element, 8... Branch line, 9... Hanging conducting wire, 10, 10'... Metal fitting, 11...
...Ring conductor, 12...Insulator, 13...Ground wire, 14...
- Feeding point, 15... Reactance element, 16... Power divider, 17, 19... Matching device, 18... Phase adjuster. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 (a) / Figure 8 (b) Figure 9 Figure 10 Figure 11

Claims (1)

[Scope of Claims] 1. Comprising a feeder line 6 supported by a support column 1, a plurality of antenna elements 2 connected to the feeder line 6, and a matching box 17 provided at the lower end of the feeder line 6, In the short-wave band log-periodic antenna in which the lower end of the feed line 6 is used as one feed point, the support column 1 is connected to the support column 1 via a metal fitting 10 provided near the top of the support column 1 and in the middle thereof. A conductive wire 9 whose lower end is tied to the ground via an insulator 12
A log-periodic antenna for a short wave band, characterized in that the lower end of the conducting wire 9 is used as a feeding point for a low frequency band within the frequency band used or as an intervening point of a reactance element 15. 2. A reactance element 15 is interposed at the lower end of the conducting wire 9, and only the lower end of the power supply line 6 is used as a power supply point, and the matching box 1
7 and the reactance element 15 are adjusted to form a unidirectional radiation pattern. 7. The short wave band log-periodic antenna according to claim 1, wherein the reactance element 15 is adjusted to provide a unidirectional radiation pattern. 3. The conductive wire 9 is composed of a plurality of conductive wires, these conductive wires are arranged around the pillar 1 at a predetermined distance from each other, their lower ends are commonly connected, and this common connection point is used as the power feeding point or intervening point. Claim 1 characterized in that
A log-periodic antenna for shortwave bands as described in .