JP2004328019A - Uhf band television broadcast receiving antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the gain and standing wave ratio with simple constitution even for a low frequency band among all UHF band television broadcast frequency bands. <P>SOLUTION: A matching device 18 is provided between a feeding point for radiators 2, 4 for all frequency bands of UHF band television broadcast and a fixing metallic fixture 16 connected to an outer conductor and a center conductor of a coaxial cable, converts the impedance of the radiators 2, 4 and the coaxial cable and converts balancing / unbalancing. Two lead wires 22, 24 of the matching device 18 at the side of the radiators 2, 4 are constituted of distributed capacitance lines 34 that are close to each other and inductive lines 42 that are apart from each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an antenna for receiving UHF band television broadcasting, and more particularly to an antenna used in the entire frequency band of UHF band television broadcasting.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an antenna for receiving a UHF band television broadcast, for example, there is an antenna disclosed in Patent Document 1.
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 61-43289
The UHF band television broadcast receiving antenna disclosed in Patent Literature 1 has two sets of radiators, and each set of radiators includes two radiating elements. The feed points of the radiating elements of these two radiators are connected via two inductance elements and further connected to an impedance matching transformer. A punched and bent metal plate is used as the inductance element.
[0005]
[Problems to be solved by the invention]
In this UHF band television broadcast receiving antenna, a metal plate is required to be manufactured in order to manufacture an inductance element, and the production is troublesome. In addition, terrestrial digital broadcasting will be started soon. In terrestrial digital broadcasting, a low frequency band is used among frequency bands (470 to 770 MHz) for UHF band television broadcasting. Even in this low frequency band, it is necessary to improve the gain and the standing wave ratio, but with the above configuration, it was not possible to sufficiently improve it.
[0006]
An object of the present invention is to provide a UHF band television broadcast receiving antenna which is easy to manufacture. Another object of the present invention is to provide a UHF band television broadcast receiving antenna with improved performance even in a low frequency band for UHF band television broadcasting.
[0007]
[Means for Solving the Problems]
The antenna for receiving UHF band television broadcasting according to the present invention has radiators for all frequency bands of UHF band television broadcasting. This radiator consists of two radiating elements. Multiple radiators may be provided. A fixture is provided for electrical and mechanical connection to the outer conductor and the center conductor of the coaxial cable. A matching device is provided between the feed point of the radiator and the fixture. The matching device performs impedance conversion of the radiator and the coaxial cable, and conversion of balance and unbalance. This matcher has two leads connected to the two feed points of the radiator. These two lead wires are constituted by a distributed capacitance line portion approaching each other and an inductive line portion separated from each other. It is possible that the distributed capacitance line part exists on the matching unit side and the inductive line part exists on the radiator side, and conversely, the distributed capacitance line part exists on the radiator side and the inductive line part matches. It is also possible to be present on the vessel side.
[0008]
In the UHF-band television broadcast receiving antenna configured as described above, an inductance based on the inductive line portion exists between the matching box and the radiator, and a capacitance component based on the distributed capacitance line portion exists between the line portions. Exists. With these inductances and capacitances, the gain and the standing wave ratio are improved even in the low frequency band of the UHF band television broadcasting. Moreover, it is used to improve the gain and standing wave ratio by using a part of the lead wire as a distributed capacitance line part and the remaining part as an inductive line part, Its manufacture is easy.
[0009]
It is desirable that the ratio of the distributed capacitance line portion to the inductive line portion is about 2.7 to 1.1. Further, it is desirable that the length of the distributed capacitance line portion is 35 mm to 75 mm, and the length of the inductive line portion is 20 mm to 50 mm.
[0010]
A distributed capacitance line portion is formed by inserting a restraining member at an interval between the two leads, and by bringing the remaining portions of the two leads into contact with a support member, thereby forming the two lines. The inductive line portion may be formed with a space between the remaining portions of the lead wires. The support member can be formed, for example, in a housing in which the radiator is housed.
[0011]
With this configuration, each of the distributed capacitance line portion and the inductive line portion can be easily formed.
[0012]
The lead wires on the fixture side of the matching device may be brought closer to each other to form a distributed capacitance line section. With this configuration, it is possible to provide a capacity on the fixture side of the matching device, thereby improving the performance in a low frequency band of the UHF band television broadcasting frequency band.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The UHF band television broadcast receiving antenna according to one embodiment of the present invention is used in a wide band of 470 MHz to 770 MHz in the entire frequency band of UHF band television broadcasting. As shown in FIG. 1 and FIG. It has a radiator, for example two sets of radiators 2,4. Although not shown, in addition to this, it has a reflector and a plurality of directors, and constitutes a Yagi antenna.
[0014]
The radiator 2 has two radiating elements 2a and 2b. These radiating elements 2a and 2b are linear conductive elements, and are attached to the housing 6 so that they are located on the same straight line. The ends of the radiating elements 2a and 2b in the housing 6 are feeders 8a and 8b. The radiator 4 also has two radiating elements 4a and 4b. The radiating elements 4a and 4b have different lengths from the radiating elements 2a and 2b, and are attached to the housing 6 in parallel with the radiating elements 2a and 2b. The ends of the radiating elements 4a and 4b inside the housing 6 are feeders 10a and 10b.
[0015]
The power supply units 8a and 10a on the same side are electrically connected to each other by a connection plate 12, and similarly, the power supply units 8b and 10b on the same side are also electrically connected by a connection plate 14. These connecting plates 12 and 14 are arranged in the housing 6 in parallel with each other, and have tabs 12a, 12b, 14a and 14b for connecting to the radiating elements 2a, 2b, 4a and 4b at their ends. .
[0016]
In the housing 6, a fixing bracket 16 for connecting the radiators 2, 4 to an unbalanced line, for example, a coaxial cable, is attached. The fixing bracket 16 is located on the radiating element 2b, 4b side between the radiators 2, 4, and has an outer conductor fixing portion 16a to which the outer conductor of the coaxial cable is fixed, and a center conductor to which the center conductor of the coaxial cable is fixed. And a fixing portion 16b.
[0017]
A matching device 18 is arranged on the side of the fixing bracket 16, for example, between the radiating elements 2a and 4a. The matching device 18 is arranged in a box 20 provided in the housing 6. The matching unit 18 converts the impedance of the radiators 2 and 4, for example, 300Ω into the impedance of a coaxial cable, for example, 75 Ω, and converts the radiators 2 and 4 that are balanced circuits into coaxial cables that are unbalanced circuits. This is a so-called 1: 4 balun for connection, which is formed by winding a ferrite core in the form of glasses and connected to two lead wires 22 and 24 connected to the radiators 2 and 4 and the fixing bracket 16. And two lead wires 26 and 28. The leads 22 and 24 are connected to the tabs 12b and 14b of the fixing plates 12 and 14, and the leads 26 and 28 are connected to the outer conductor fixing part 16a and the center conductor fixing part 16b.
[0018]
As shown in FIG. 1 in an enlarged manner, one restraining member, for example, a vinyl tube 30 is inserted into both the lead wires 22 and 24 immediately after being led out from the matching unit 18, for example, at a position led out by about 4 mm from the matching unit 18. Have been. The length of this vinyl tube is about 8 mm. The vinyl tubes 32 are also inserted into the lead wires 22 and 24 apart from the lead wires. Since the vinyl tubes 30 and 32 are inserted at positions separated from the lead wires 22 and 24, the portions of the lead wires 22 and 24 covered by the vinyl tubes 30 and 32 and the lead wires between the vinyl tubes 30 and 32 The portions 22 and 24 are in contact with each other and constitute a distributed capacitance line section 34. The length of the distributed capacitance line section 34 is, for example, 40 mm. In addition, what is indicated by reference numeral 36 is a blocking member for preventing the lead wires 22 and 24 from freely moving, for example, a pin, and the portions of the lead wires 22 and 24 between the vinyl tubes 30 and 32 are It is in contact with this pin 36.
[0019]
The lead wires 22, 24 from the vinyl tube 32 are separated from each other by support members provided at remote positions, for example, pins 38, 40, and connected to the connection tabs 12b, 14b, respectively. I have. The distance between the pins 38 and 40 is about 10 mm, and the portion of the lead wires 22 and 24 between the pins 38 and 40 is the most widely spaced. Since the distance between these lead wires 22 and 24 is wide, there is only a very small capacitance between them, and each functions as an inductive line. That is, this portion is the inductive line portion 42. The length of the guide line section 42 is selected to be, for example, about 22 mm. That is, the ratio of the length of the distributed capacitance line section 34 to the length of the inductive line section 42 is about 1.8 (= 40/22).
[0020]
Further, the vinyl tubes 44 are also inserted into portions of the lead wires 26 and 28 on the unbalanced side of the matching device 18 immediately after being led out from the matching device 18. The lead wire 26 is connected to the outer conductor fixing portion 16a, and the lead wire 28 is connected to the center conductor fixing portion 16b, the length of which is about 16 mm, and the length of the vinyl tube 44 is about 12 mm. . Due to the restraint by the vinyl tube 44, the distributed capacitance line portion 46 is also formed on the unbalanced side. Although not shown, a capacitor of about 1.5 pF is connected between the center conductor fixing portion 16b and the outer conductor fixing portion 16a.
[0021]
FIG. 3 shows an equivalent circuit diagram near the radiators 2 and 4 of the UHF band television broadcast receiving antenna. That is, the radiating elements 2a and 4a of the radiators 2 and 4 are connected by the connecting plate 12, and the radiating elements 2b and 4b are connected by the connecting plate 14. The connection tabs 12b and 14b of the connection plates 12 and 14 are connected to the balanced side of the matching unit 18 via the reactances 42a and 42b of the induction line section 42, and are connected between both ends on the balanced side based on the distributed capacitance line 34. The capacity 34a is connected. A capacitance 46 a based on the distributed capacitance line 46 is connected between the unbalanced sides of the matching unit 18.
[0022]
Since the reactances 42a and 42b and the capacitor 34a are provided on the unbalanced side of the matching unit 18 as described above, the gain and the standing wave ratio are improved in a low frequency band of the UHF band television broadcasting frequency band. In addition, this improvement can be performed by a simple operation of inserting the tubes 30 and 32 into the lead wires 22 and 24 and hooking the lead wires 22 and 24 to the pins 38 and 40, and performing processing such as punching of a metal plate. Is performed to form an inductance element, and further, such a troublesome work as mounting this inductance element is not required at all.
[0023]
In the radiators 2 and 4 as described above, the gain and the standing wave ratio versus frequency characteristics when the length of the distributed capacitance line portion 34 is fixed and the length of the inductive line portion 42 is changed are shown in FIG. Show. Here, the length of the distributed capacitance line portion 34 was set to 40 mm, and the length of the inductive line portion 42 was changed to 8, 15, 25, 35, and 45 accordingly. When the length of the inductive line portion 42 is 8 mm, the gain is the smallest and the standing wave ratio is the worst in a low frequency band of the UHF band television broadcast. When the length of the inductive line portion 42 is 45 mm, the gain is almost the same as the other in the low frequency band, but the standing wave ratio is close to 2, which is not preferable. Therefore, it is desirable that the ratio of the length of the distributed capacitance line portion 34 to the length of the inductive line portion 42 be about 1.1 (40/35) to 2.7 (40/15). In particular, when this ratio is set to 1.6 (40/25), this is the most desirable because the standing wave ratio and the gain are good in a low frequency band. FIG. 5 shows the gain and standing wave ratio versus frequency characteristics of the 14-element Yagi antenna using the radiators 2 and 4 when the length of the induction line section is changed as in FIG. The same can be said from now on.
[0024]
FIG. 6 shows that the lengths of the distributed capacitance line portion 34 and the inductive line portion 42 in the radiators 2 and 4 are 90 mm and 60 mm (ratio 1.5), 75 mm and 50 mm (ratio 1.5), and 60 mm and 40 mm. (Ratio 1.5), 45 mm and 30 mm (ratio 1.5), 35 mm and 20 mm (ratio 1.75), and gain vs. standing wave ratio versus frequency characteristics when changed to 10 mm and 0 mm. In the case where the length of the distributed capacitance line portion 34 is 90 mm and the length of the inductive line portion 42 is 60 mm, the standing wave ratio is deteriorated in a high frequency band, the gain is reduced, and the distribution is reduced. When the length of the capacitance line section 34 is 10 mm and the length of the inductive line section 42 is 0 mm, the gain decreases and the standing wave ratio deteriorates in the low frequency band and the high frequency band. Therefore, it is desirable that the length of the distributed capacitance line portion 34 be 75 mm to 35 mm and the length of the inductive line portion 42 be 50 mm to 20 mm. FIG. 7 shows a 14-element UHF-band television broadcast receiving Yagi antenna including radiators 2 and 4 in which the lengths of the distributed capacitance line section 34 and the inductive line section 42 are changed in the same manner as in FIG. FIG. 5 is a graph showing gain and standing wave ratio vs. frequency characteristics in the above case. Even in the case of 14 elements, almost the same results as in the case of FIG. 5 can be obtained. In each of the frequency characteristic diagrams, the symbol G is added to the end of the code to show the gain versus frequency characteristic diagram, and the symbol V added to the end of the code is the standing wave ratio to the frequency characteristic diagram. It is.
[0025]
By appropriately selecting the lengths of the distributed capacitance line section 34 and the inductive line section 42 in this manner, it is possible to obtain a good gain and a standing wave ratio in the entire frequency band of the UHF band television broadcast. Even if a low frequency band of the UHF band television broadcasting is used in the terrestrial digital broadcasting, the terrestrial digital broadcasting can be satisfactorily received.
[0026]
In the above embodiment, two sets of radiators 2 and 4 are used, but in some cases, only one set of radiators may be used. In addition, a stopper can be used as the fixing bracket 16. In the above-described embodiment, the pins 38 and 40 formed separately are used as the support members. Alternatively, for example, members in which grooves for inserting the lead wires 22 and 24 are formed at intervals are used. You can also. In the above embodiment, the lead wire 22 is connected to the connection tab 12b, and the lead wire 24 is connected to the connection tab 14b. Conversely, the lead wire 24 is connected to the connection tab 12b, It is also possible to connect the lead wire 22 to the tab 14b. The lead wire 22 is connected to the connection tab 12b, and the lead wire 24 is connected to the connection tab 14b. Conversely, the lead wire 24 is connected to the connection tab 12b, and the lead wire 22 is connected to the connection tab 14b. There may be a difference in the obtained characteristics between the case where the connection is made and the case where the connection is made.
[0027]
【The invention's effect】
As described above, in the antenna for receiving UHF band television broadcasting according to the present invention, a good gain and a standing wave ratio can be obtained in the entire frequency band of the UHF band television broadcasting, and the manufacturing is easy.
[Brief description of the drawings]
FIG. 1 is an enlarged view of the vicinity of a radiator in a UHF band television broadcast receiving antenna according to an embodiment of the present invention.
FIG. 2 is a partially omitted plan view showing the vicinity of a radiator of the antenna of FIG. 1;
FIG. 3 is an equivalent circuit diagram near a radiator of the antenna of FIG. 1;
FIG. 4 is a graph showing gain and standing wave ratio versus frequency characteristics when the length of the distributed capacitance line portion is fixed and the length of the inductive line portion is varied in the radiator of the antenna of FIG. 1;
FIG. 5 is a diagram illustrating gain and standing wave ratio versus frequency characteristics when the length of the distributed capacitance line portion is fixed and the length of the inductive line portion is changed in the antenna using the radiator of FIG. 1; is there.
FIG. 6 is a graph illustrating gain and standing wave ratio versus frequency characteristics when the length of the distributed capacitance line portion and the length of the inductive line portion are changed in the radiator of the antenna of FIG. 1;
7 is a gain and standing wave ratio vs. frequency characteristic diagram when the length of the distributed capacitance line portion and the length of the inductive line portion are changed in the antenna using the radiator of FIG. 1;
[Explanation of symbols]
2 4 radiator 16 fixture 18 matching box 22 24 lead 34 distributed capacitance line section 42 inductive line section

Claims (5)

A radiator for all frequency bands of UHF band television broadcasting,
An outer conductor of the coaxial cable, and a fixing bracket electrically and mechanically connected to the center conductor,
A matching device, which is provided between a feed point of the radiator and the fixture, performs impedance conversion of the radiator and the coaxial cable, and performs conversion of balance and unbalance,
An antenna for receiving UHF band television broadcasting, comprising: two distributed wires on the radiator side of the matching device, the distributed capacitance line portion being close to each other and the inductive line portion being separated from each other. 2. The UHF band television broadcast receiving antenna according to claim 1, wherein a ratio of said distributed capacitance line portion to said inductive line portion is about 2.7 to 1.1. The UHF band television broadcast receiving antenna according to claim 2, wherein the length of the distributed capacitance line portion is 35 mm to 75 mm, and the length of the inductive line portion is 20 mm to 50 mm. Antenna. 2. The antenna for receiving UHF band television broadcasting according to claim 1, wherein said distributed capacitance line portion is formed by inserting a restraining member along a part of said two lead wires at an interval. A UHF band television broadcast receiving antenna, wherein the inductive line portion is formed at an interval between the remaining portions of the two lead wires by bringing the remaining portions of the lead wires into contact with a supporting member. 2. The antenna for receiving UHF band television broadcasting according to claim 1, wherein the lead wires of the matching device on the side of the fixing bracket are brought close to each other to form a distributed capacitance line section.

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