CN104137328A

CN104137328A - Directional coupler

Info

Publication number: CN104137328A
Application number: CN201280070947.9A
Authority: CN
Inventors: 莲池健一; 板垣广务
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2012-03-14
Filing date: 2012-09-14
Publication date: 2014-11-05
Anticipated expiration: 2032-09-14
Also published as: WO2013136557A1; JP5439527B2; EP2827441A4; JP2013192084A; EP2827441B1; CN104137328B; EP2827441A1

Abstract

A directional coupler according to the present embodiment includes a dielectric substrate (10), a main line (11) formed on the front surface of the dielectric substrate (10), a sub line (12) formed on the front surface or the rear surface of the dielectric substrate (10) and placed with a predetermined gap from the main line (11) when the dielectric substrate (10) is viewed in plan, and an opening (14) penetrating the dielectric substrate (10) between the main line (11) and the sub line (12).

Description

Directional coupler

Technical field

Embodiments of the present invention relate to the directional coupler using in the power amplifier of for example using in the powerful digital video transmitter of transmission.

Background technology

In the past, about the general structure of directional coupler, the whole face in the back side that uses dielectric base plate was earthing conductor and the microstrip line structure at its surface construction main line and auxiliary line (directional coupler) pattern.The coupling circuit that becomes a part for auxiliary line separates small arranged spaced with main line on substrate the line pattern of appropriate length.

As everyone knows, generally speaking, if the length of this coupling circuit (distance between coupling port and isolated port) is made as to λ/4 with respect to the wavelength X of the transmission signal going out from main line detection, directivity is best.But at UHF wave band, the circuit of λ/4 wavelength is longer, it is large-scale that circuit becomes.Therefore, even sacrifice directivity in certain degree, the also normal loop coupling circuit with the appropriate length shorter than λ/4 that uses.

Formerly technical literature

Patent documentation

Patent documentation 1: Japanese kokai publication hei 7-336117 communique

Summary of the invention

The problem of Xie Decision is Yaoed in invention

But, transmitting in the device of high-power signal with power amplifier etc. in digital video transmitter, the level of the power output of transmission lines is larger, therefore while carrying out detection, paying attention to the directivity (isolation characteristic) of directional coupler to high-power.Therefore, require to realize the small-sized directional coupler that can improve directivity.

The object of present embodiment is, high directivity and small-sized directional coupler are provided.

For solving the means of problem

The related directional coupler of present embodiment possesses: dielectric base plate; Main line, is formed at the surface of described dielectric base plate; Auxiliary line, is formed at surface or the back side of described dielectric base plate, and in the time overlooking described dielectric base plate, this auxiliary line and described main line separate predetermined distance and configure; Peristome, is arranged between described main line and described auxiliary line, and this peristome connects described dielectric base plate.

Brief description of the drawings

Fig. 1 is the stereogram that the structure of the directional coupler related to present embodiment represents.

Fig. 2 is vertical view and the cutaway view of the directional coupler shown in Fig. 1.

Fig. 3 is the figure that the simulation result of the directional coupler shown in Fig. 1 is represented.

Fig. 4 is the stereogram that the structure of the directional coupler related to comparative example represents.

Fig. 5 is vertical view and the cutaway view of the directional coupler shown in Fig. 4.

Fig. 6 is the figure that the simulation result of the directional coupler shown in Fig. 4 is represented.

Embodiment

Below, with reference to accompanying drawing, the related directional coupler of present embodiment is described.

Fig. 1 is the stereogram that the structure of the directional coupler related to present embodiment represents, digital video transmitter is on the ground represented as an example with the directional coupler using in high power amplifier.Fig. 2 (a) is the vertical view of the directional coupler of Fig. 1, and Fig. 2 (b) is A-A ' cutaway view.In addition, in Fig. 1, radome 15 omits.

Main line 11 is disposed at the surface of dielectric base plate 10, and auxiliary line 12 is formed at the back side of dielectric base plate 10, and in the time overlooking dielectric base plate 10, auxiliary line 12 separates predetermined distance and configures with main line 11.In addition, to be formed with the ground plane 13 of auxiliary line 12 on the surface of dielectric base plate 10 with the overlapping mode of auxiliary line 12.Consider resistance to electric power, main line 11 uses the suspension circuit configurations that can widen line width.Auxiliary line 12 uses microwave transmission band structure.In addition, also can replace auxiliary line 12 and ground plane 13 and auxiliary line 12 is configured in to the surface of dielectric base plate 10.

And, between main line 11 and auxiliary line 12, be provided with peristome 14.This peristome 14 connects dielectric base plate 10.The distance B 2 of the width W of this peristome 14, the shape of length L, the distance B 1 from main line 11 to peristome and the coupling circuit part from peristome 14 to auxiliary line 12, optimizes by electromagnetic-field simulation.

At this, the impact that peristome 14 is caused describes.Main line 11 and auxiliary line 12 be facing to and clip the structure of dielectric base plate 10, be air at its periphery, therefore the phase velocity of even mould is faster than strange mould, directivity is deteriorated for this reason.To this, in the present embodiment, by the peristome 14 a part of dielectric of power down medium substrate 10 of making a return journey is set, thereby can make the phase velocity of two moulds approach.For this reason, can improve the directivity of directional coupler.

The simulation result of the related directional coupler of present embodiment has been shown in Fig. 3.Shown in the formula (1) of following note, the directivity D of directional coupler can by from input port P1 the degree of coupling I to coupling port P3 and from input port P1 the difference of the degree of coupling C to isolated port P4 calculate.

Directivity D=|I-C|[dB] formula (1)

Known according to the result of Fig. 3, during by above-mentioned formula (1) calculated direction D, obtain the directivity of 31dB left and right.In addition, the S2 in Fig. 3,1 is equivalent to I, S3,1 is equivalent to C.

At this, in order to compare with present embodiment, the structure of the related directional coupler of comparative example is shown in Fig. 4.Fig. 5 (a) is the vertical view of the directional coupler of Fig. 4, and Fig. 5 (b) is B-B ' cutaway view.Except peristome 14 is not set, be the directional coupler same structure related with present embodiment.

In Fig. 5 (a), the length of establishing coupling circuit is Lc (< λ/4 wavelength), and the distance that is set to main line is Dc.The degree of coupling decides by Dc.Generally speaking, be widely used the Wiring construction of the loop antenna shape that the length L c of coupling circuit of directional coupler is shorter than λ/4 wavelength.But in this structure, even mould is different from the phase place transfer rate of strange mould, therefore has the deteriorated shortcoming of directivity of directional coupler.In the situation of the weak loose coupling of the degree of coupling, there is further deteriorated tendency of directivity.

The simulation result of the directional coupler of Fig. 4 has been shown in Fig. 6.In the structure of Fig. 4, known according to the result of Fig. 6, when by above-mentioned formula (1) calculated direction D, directivity is 11dB left and right.

Fig. 3 and Fig. 6 are compared, and in the directional coupler of present embodiment, compared with the directional coupler of Fig. 4, directivity has been improved 20dB, even if the coupling circuit part of auxiliary line 12 does not have the length of λ/4 wavelength, also can obtain enough directivity.Therefore, known, by being set, can improve this peristome 14 directivity of directional coupler.

As previously discussed, in the present embodiment, the peristome of proofreading and correct use between main line and auxiliary line by arranging can improve directivity.Even if coupling circuit does not have the length of λ/4 wavelength, also can obtain high directivity.Therefore,, by present embodiment, can realize high directivity and small-sized directional coupler.

And, as the application examples of the related directional coupler of present embodiment, for example, this directional coupler can be arranged to the output transmission lines of the high power amplifier that the digital video transmitter of UHF (Ultra-High Frequency: superfrequency) wave band uses.Be configured between the synthetic output and out connector of power amplifier the circuit that the output level with work to power output and reflective level detect.

In addition, several execution modes are illustrated, but these execution modes are to point out as an example, intention does not lie in restriction scope of invention.These new execution modes can be implemented with other variety of ways, in the scope of purport that does not depart from invention, can carry out various omissions, displacement, change.These execution modes and distortion thereof, be contained in scope of invention, purport, and be contained in the invention of claim secretary Load and the scope that is equal in.

Claims

1. a directional coupler, is characterized in that, possesses:

Dielectric base plate;

Main line, is formed at the surface of described dielectric base plate;

Auxiliary line, is formed at surface or the back side of described dielectric base plate, and in the time overlooking described dielectric base plate, this auxiliary line and described main line separate predetermined distance and configure; And

Peristome, is arranged between described main line and described auxiliary line, and this peristome connects described dielectric base plate.

2. directional coupler as claimed in claim 1, is characterized in that,

With respect to the wavelength X of the transmission signal detecting from described main line, Length Ratio λ/4 of described auxiliary line are short.