JP2003318613A - Waveguide microstrip transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a low-cost waveguide microstrip transducer easy to assemble. <P>SOLUTION: A waveguide block has an identically shaped upper and lower waveguide halves 11a, 11b divided along a plane perpendicular to the H-plane of a waveguide at the center position of the H-plane. Both halves 11a, 11b are formed each by the same die. A microstrip line is formed on a resin-made printed board 13. The lower waveguide half has a small groov-like hold 19 deeper than the thickness of the printed board. The top end of the printed board 13 is inserted into the hold 19, then the upper waveguide half 11a is bonded to the lower waveguide half 12a to form the waveguide block, resulting in the upper waveguide half 11a crushing the top end of the printed board 13, to squeeze the top end between the upper and lower waveguide halves 11a, 12a. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide microstrip converter for electrically connecting a waveguide and a microstrip line, and more particularly to a waveguide microstrip converter used in the millimeter wave band. It is a thing.

[0002]

2. Description of the Related Art In recent years, with the spread of high-speed data communication lines, the band of communication lines has been widened, and the millimeter band frequency band is being used to cope with the wide band of communication lines. In such a frequency band, a waveguide and a microstrip line are mainly used as a transmission line in consideration of attenuation and loss. Since the waveguide has low loss, it is mainly used for the power feeding system (feeding transmission line) to the antenna, and the microstrip line is easy to handle, so it is used as the transmission line (transmission line) in the transceiver circuit. ing. Then, when connecting the antenna and the transmission / reception circuit, it is necessary to electrically connect the waveguide and the microstrip line, and when connecting the waveguide and the microstrip line electrically, A wave tube microstrip converter is used.

FIG. 11 is a perspective view showing the structure of a conventional waveguide microstrip converter. As shown in FIG. 11, a flange 92 is provided at one end of the rectangular waveguide section 91.
Are attached by brazing. Flange 92
Is connected to a waveguide (not shown) used as an antenna feeding system. At the other end of the waveguide section 91, for example,
A short member is brazed to form a short surface 93. In the waveguide section 91, from the H-plane to the E-plane of the waveguide formed in the waveguide section 91 at the position of the quarter wavelength (λ / 4) of the guide wavelength λ with the short surface 93 as the starting point. On the other hand, the printed circuit board 94 is vertically inserted. Waveguide formed in waveguide section 91 and printed circuit board 9
The microstrip line formed in 4 is electromagnetically coupled. The microstrip line formed on the printed board 94 is joined to a transmission / reception circuit (not shown). An alumina substrate having a high dielectric constant and a low loss is used as the printed circuit board 94 to reduce the size and stability of the converter itself.

After inserting the printed circuit board 94 into the waveguide section 91, the printed circuit board 94 is fixed to, for example, a housing (not shown) of a radio device (for example, a radio frequency (RF) module). However, as described above, since the alumina substrate is used as the printed circuit board 94 (that is, the alumina substrate is hard), it is difficult to fix it to the housing with screws. For this reason, generally, an alumina substrate is soldered to a sub metal block (not shown) called a carrier, and then the sub metal block is fixed to the housing with screws.

[0005]

Since the conventional waveguide microstrip converter is constructed as described above,
That is, since the waveguide portion, the flange, and the short surface are joined by brazing, considering that the joining by brazing is expensive, the waveguide microstrip converter itself becomes expensive. There were challenges.
Further, there is a problem that it is difficult to mass produce the joining by brazing.

Further, in the conventional waveguide microstrip converter, an alumina substrate is used as a printed circuit board, and considering that the alumina substrate is expensive, the waveguide microstrip converter itself becomes more expensive. Will end up.

In addition, as described above, when an alumina substrate is used as the printed circuit board, the alumina substrate is once soldered to the sub metal block, and then the sub metal block is fixed to the case with screws to fix the alumina substrate to the case. There is also a problem that it is necessary to fix it to the body, and as a result, the number of working steps is increased and the cost is increased.

As described above, the conventional waveguide microstrip converter has a problem that it is difficult to mass-produce it and the cost is high.

The present invention has been made to solve the above problems, and an object thereof is to obtain a waveguide microstrip converter which is inexpensive and easy to assemble.

[0010]

In the waveguide microstrip converter according to the present invention, the waveguide section is divided into two parts by a plane perpendicular to the H plane at the central position of the H plane of the waveguide. Having first and second waveguide main body portions, the first and second waveguide main body portions are formed using the same mold, and are joined together while holding the printed circuit board. Is.

In the waveguide microstrip converter according to the present invention, the insulating material of the printed circuit board is made of a resin material.

In the waveguide microstrip converter according to the present invention, the printed circuit board is sandwiched between the first and second waveguide main body portions at one end thereof.

In the waveguide microstrip converter according to the present invention, the second waveguide main body has a groove-like shape in which one end of the printed circuit board is arranged on the joint surface with the first waveguide main body. It has a holding part, the depth of the holding part is smaller than the thickness of the printed circuit board, and one end of the printed circuit board is crushed by the first waveguide main body part.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. Embodiment 1. 1 is an exploded perspective view showing a waveguide microstrip converter according to a first embodiment of the present invention. FIG. 2 is a plan view of the joint surface between the upper portion of the waveguide shown in FIG. 1 and the lower portion of the waveguide seen through from above. FIG. 3 is a sectional view taken along the line AA in FIG. 1 in a state where the waveguide microstrip converter shown in FIG. 1 is assembled. In the figure, 11 is a waveguide upper part (waveguide part), 12 is a waveguide lower part (waveguide part), 13 is a printed circuit board, and 14 is a screw.

The waveguide upper portion 11 has a hollow upper waveguide main body portion (first waveguide main body portion) 11a, and one end portion of the upper waveguide waveguide main body portion 11a has a short surface portion 15a. And a flange portion 16a is provided at the other end. Further, a flange portion 10a is provided on one side surface portion of the waveguide upper main body portion 11a. Waveguide upper body 11a
Is integrally formed with the flange portion 16a using, for example, a mold.

Similarly, the lower waveguide portion 12 has a hollow lower waveguide main body portion (second waveguide main body portion) 12a, and one end portion of the lower waveguide waveguide main body portion 12a is provided. Is the short side 1
5b is defined, and the flange portion 16b is provided at the other end. Further, a flange portion 10b is provided on one side surface portion of the lower waveguide body portion 12a. The lower waveguide body 12a is integrally formed with the flange portion 16b using the same mold as that used when the upper waveguide body 11a is molded. As a result, the waveguide upper body 11
a and the lower waveguide main body part 12a are divided into two parts by dividing a waveguide part described later by a surface perpendicular to the H surface at the center position of the H (magnetic field) surface of the waveguide formed in the waveguide part. It will be obtained.

As described above, the waveguide upper body portion 11a is formed.
After forming the lower waveguide main body 12a, the flange 10a is integrally attached to the upper waveguide main body 11a on one side surface of the upper waveguide main body 11a.
a is separately processed and attached, and is attached to the waveguide upper main body portion 11a) to become the waveguide upper portion 11. Then, screw holes 17 are formed in the upper waveguide 11 by cutting or the like. Further, the lower waveguide 12 of the upper waveguide 11
A groove-shaped printed circuit board insertion port portion 18a extending from the flange portion 10a side to the cavity side is formed on the joint surface with the.

Similarly, a flange portion 10b is integrally attached to the lower waveguide body 12a on one side surface portion of the lower waveguide body 12a (this flange portion 10b is separately processed to form a waveguide. Attached to the pipe body 12a),
It becomes the lower part 12 of the waveguide. Then, screw holes 17 are formed in the lower portion 12 of the waveguide by cutting or the like. Further, a groove-shaped printed board insertion opening 18b extending from the flange portion 10b side toward the cavity side and a printed board insertion opening portion 18b across the cavity are provided on the joint surface of the lower waveguide portion 12 with the upper waveguide portion 11. Printed circuit board holder 1 facing the groove
9 is formed. In the illustrated example, the printed circuit board insertion opening 18b has a first portion located on the flange portion 10b side and a second portion located on the cavity side, and the first portion is the second portion. Wider than. The depth of the printed board holding portion 19 is smaller than the thickness of the printed board 13.

The flange portions 16a and 16b and the flange portions 10a and 10b are provided with mounting holes 16 respectively.
c and 10c are formed and are attached to the waveguide microstrip converter using these attachment holes 16c and 10c as described below.

The printed circuit board 13 is inserted and placed in the aforementioned printed circuit board insertion opening 18b. Printed circuit board 1
A resin substrate is used for 3 and a microstrip line is formed. 13a is a strip conductor of the microstrip line. In the illustrated example, the printed circuit board 1
3 is provided with an elongated insertion end 13b at one end thereof, and when the printed board 13 is inserted and placed in the printed board insertion opening 18b, the insertion end 13b prints across the cavity. It reaches the substrate holder 19. At this time, the other end of the printed circuit board 13 slightly projects outward from the flange 10b.

In this way, after the printed circuit board 13 is inserted and placed on the lower waveguide 12, the upper waveguide 11 and the lower waveguide 12 are joined together in the direction indicated by the broken arrow in FIG. Match each other. When the waveguide upper portion 11 and the waveguide lower portion 12 are butted against each other at the joint surface, the screw hole 17 formed in the waveguide upper portion 11 and the screw hole 17 formed in the waveguide lower portion 12
And match. Then, the screw 14 is passed through the screw hole 17 and screwed. When the screws are screwed in this way, the waveguide upper portion 11 and the waveguide lower portion 12 are integrated into a waveguide portion. At this time, the printed circuit board insertion ports 18a and 18b form the printed circuit board insertion port 18 connected to the cavity, and the short surface portions 15a and 15b form the short surface 15. Further, the flange portions 16a and 16
b is integrated into the flange 16 and the flange portion 10
The a and 10b are integrated to form the flange 10.

When the waveguide upper part 11 and the waveguide lower part 12 are assembled by using the screw 14, the depth of the printed board holding portion 19 is smaller than the thickness of the printed board 13 as described above, and therefore, the insertion end. The tip of the portion 13b is crushed by the waveguide upper portion 11, and the insertion end portion 13b, that is, the printed circuit board 13 is sandwiched between the waveguide upper portion 11 and the waveguide lower portion 12.

The waveguide microstrip converter having the above structure is attached to a waveguide (not shown) used as an antenna feeding system by screwing a screw through the mounting hole 16c of the flange 16 to attach the flange 10 to the flange 10.
By passing a screw through the mounting hole 10c of
It is attached to the housing of a radio frequency (RF) module. The other end of the printed circuit board 13 (the end opposite to the insertion end 13a) is screwed to the housing of the RF module 21 with a screw 22, as shown in FIG. As a result, both ends of the printed circuit board 13 are fixed. Note that FIG. 4 shows a state in which the waveguide upper portion 11 is removed.

By the way, considering that the resin-based substrate is soft as the printed-circuit board 13 is used, when external factors such as vibration and shock are applied to the printed-circuit board 13, the resin-based board is formed on the printed-circuit board 13. The electrical characteristics of the microstrip line that is being used may change (that is, the electrical characteristics are affected). In particular, in the millimeter wave band, since the wavelength is extremely short, the electrical characteristics are susceptible to fluctuations, and it is necessary to firmly hold the printed circuit board 13 in the cavity of the waveguide section. Here, one end side (insertion end 13b) of the printed circuit board 13 is sandwiched between the waveguide upper part 11 and the waveguide lower part 12, and the printed circuit board 13
Since the printed circuit board 13 is held by screwing the other end side of the printed circuit board 13 to the housing, the printed circuit board 13 is not affected by external factors.
Does not change, and as a result, the electrical characteristics do not change. In addition, as described above, if the waveguide microstrip converter is assembled, naturally one end side of the printed board 13 is sandwiched between the upper waveguide part 11 and the lower waveguide part 12, and the other end side of the printed board 13 is casing. The printed circuit board 13 can be easily fixed because it only needs to be screwed to the body.

Here, the waveguide microstrip converter manufactured as described above will be specifically described with reference to FIGS. Now, in FIG. 4, when the lower waveguide portion 12 is enlarged together with the insertion end portion 13b of the printed circuit board 13, a view shown in FIG. 5 is obtained.

In FIG. 5, the distance from the center of the strip conductor 13a (hereinafter referred to as the pattern center) to the short surface portion 15b is set to 2.5 mm. On the other hand, the width of the board insertion opening 18b was set to 3.2 mm. And
WRJ260 was used as the waveguide section. That is, the width of the cavity is 4.318 mm and the height is 8.636 mm (see FIG.
(See (b)), and the thickness of the waveguide lower main body 12a (and the waveguide upper main body 11a) is set to 3.85 mm.

FIG. 6 shows the insertion end portion 13 of the printed circuit board 13.
It is a figure which expands and shows b, and insert end 13b (namely,
The printed circuit board 13) is a Teflon (registered trademark) plate having a plate thickness of 0.254 mm and a dielectric constant of 2.2. The width of the insertion end 13b was 3 mm, and the width of the strip conductor 13a formed on the insertion end 13b was 0.7 mm. A rectangular pattern 1 having a width of 1.35 mm and a length of 1.55 mm is provided at the tip of the strip conductor 13a.
3c was formed. Then, when the insertion end portion 13b is inserted into the printed circuit board holding portion 19, one side of the rectangular pattern 13c (one side of the board insertion opening side) and the inner side surface of the waveguide section (the inner side surface of the board insertion opening side (hereinafter, referred to as the guiding side) The distance to the end face of the wave tube)) was 0.3 mm. At the insertion end 13b,
Up to the end face of the waveguide, copper foil was applied to the back surface (the surface facing the back side of the paper in FIG. 5) (no copper foil was applied to the back surface after the end surface of the waveguide). Furthermore, as shown in FIG.
From the bottom surface of the cavity defined in the waveguide section to the printed circuit board 1
The height to the upper surface of 3 is 4.318 mm, the printed circuit board 1
The distance from the upper surface of No. 3 to the upper inner surface of the substrate insertion port was 1 mm (see also FIG. 3B).

After setting the dimensions of the waveguide microstrip converter as described above, simulation is performed using an electromagnetic field simulator HFSS (trade name; manufactured by Agilent) by the finite element method, and the reflection characteristic S11 is obtained.
The conversion characteristics (conversion loss) S21 were examined. The simulation results are shown in FIGS. 8 and 9.

As shown in FIG. 8, conversion characteristics (conversion loss)
In S21, the frequency band is approximately 20 GHz and thereafter, the amplitude is almost constant at 0 dB, and the frequency band is 17 G
The amplitude (dB) decreases from Hz to 18 GHz. That is,
It can be seen that the cutoff frequency is 17 GHz to 18 GHz. On the other hand, in the reflection characteristic S11, the amplitude is the lowest in the frequency band around 26 GHz. Generally, a waveguide has a cutoff frequency with respect to its long side, and its characteristic is that of a bypass filter. In the above-mentioned WRJ260 waveguide, since the long side is 8.636 mm, its cutoff frequency is around 17.4 GHz.

Thus, in the simulation result,
It can be seen that the cutoff frequency is in the range of 17 GHz to 18 GHz, and thereafter, a constant amplitude level is obtained and the characteristics are wideband.

FIG. 9 is a diagram in which the characteristics around the frequency of 26 GHz are extracted. In the vicinity of the frequency of 26 GHz, the conversion characteristic (conversion loss) S21 is 0.1 dB or less and the reflection characteristic S.
11 is 27 dB or more, and it can be seen that good characteristics are obtained.

Here, an RF module using the above-mentioned waveguide microstrip converter will be described. Here, subscriber wireless access (FW) using the 26 GHz band is used.
A) An example in which the above-mentioned waveguide microstrip converter is used in the RF module used in the system will be described. It should be noted that this FWA system is required to have low loss electrical characteristics at 25 to 27 GHz.

The RF module shown in FIG. 10 includes a circulator 30, a first waveguide microstrip converter (reception-system waveguide microstrip converter) 31, a low noise amplifier 32, and a first microstrip bandpass filter. (BPF) 33, down converter 34, local circuit 35, up converter 36, second BPF
37, a high power amplifier 38, and a second waveguide microstrip converter (transmission system waveguide microstrip converter) 39, and an up converter 36,
The second BPF 37 and the high power amplifier 38 are connected by the microstrip line 35a to form a transmission path. On the other hand, the low noise amplifier 32, the first BPF3
3 and the down converter 34 are connected by a microstrip line 35b to form a reception path.
The local circuit 35 is connected to the transmission path and the reception path, and transmission / reception is performed as described later. In addition, the receiving system waveguide microstrip converter 31
The transmission system waveguide microstrip converter 39 is shown in FIG.
It has the configuration described in.

The low noise amplifier 32 is connected to the receiving waveguide microstrip converter 31 (that is, is connected to the printed circuit board 13 shown in FIG. 1), and the receiving waveguide microstrip converter is connected. Reference numeral 31 is connected to the circulator 30 via a waveguide. The circulator 30 is connected to an antenna (not shown) via a waveguide. Similarly, the high power amplifier 38
Is connected to the transmission waveguide microstrip converter 39 (that is, is connected to the printed circuit board 13 shown in FIG. 1), and the transmission waveguide microstrip converter 39 is connected to the waveguide. It is connected to the circulator 30 via.

In the illustrated RF module, the circulator 30 switches between transmission and reception, and at the time of reception, the received signal transmitted through the waveguide is the circulator 30.
Is given to the receiving waveguide microstrip converter 31. Then, the reception system waveguide microstrip converter 31 supplies the reception signal from the waveguide to the microstrip line 35a side (hereinafter referred to as waveguide microstrip conversion). This received signal is amplified by the low noise amplifier 32, and the first BPF 33 is amplified as an amplified received signal.
Given to. The first BPF 33 removes unnecessary waves from the amplified reception signal and supplies the signals to the down converter 34.
The amplified reception signal is mixed with the local signal supplied from the local circuit 35 by the down converter 34 to be a reception intermediate frequency signal. Then, reception processing such as demodulation processing is further performed on the received intermediate frequency signal.

On the other hand, at the time of transmission, the transmission intermediate frequency signal is mixed with the local signal by the up converter 36,
It is used as a transmission signal. After that, from this transmission signal, the second B
After removing unnecessary waves by the PF 37, the transmission signal is amplified by the high power amplifier 38 and becomes an amplified transmission signal. And
Waveguide microstrip conversion is performed by the transmission system waveguide microstrip converter 39, and the amplified transmission signal is supplied to the antenna via the circulator 30 and the waveguide, and is radiated as a transmission wave.

According to such an RF module, the same waveguide microstrip converter may be prepared for both the reception system waveguide microstrip converter 31 and the transmission system waveguide microstrip converter 39. The receiving waveguide microstrip converter 31 and the transmitting waveguide microstrip converter 39 can be easily manufactured.

As described above, according to the first embodiment, the printed circuit board on which the microstrip line is formed is a resin-based substrate, and the waveguide portion is located at the center of the H surface of the waveguide. A waveguide upper main body and a waveguide lower main body, which are divided into two parts by a plane perpendicular to, are molded in the same mold, and the tip of the printed circuit board is placed on the joint surface of the waveguide lower main body. Grooved holding part is formed, the depth of the holding part is made smaller than the thickness of the printed circuit board, and the tip of the printed circuit board is placed in the holding part. Since the lower body is joined and the tip of the printed circuit board is crushed by the upper waveguide body, one end of the printed circuit board is sandwiched between the upper waveguide body and the lower waveguide body. There is an effect that the printed circuit board can be easily held. Since the printed circuit board is made of resin, it is inexpensive, and the other end of the printed circuit board can be easily screwed to the wireless device housing or the like. Moreover, the waveguide upper body and the waveguide lower body can be molded in the same mold, and as a result,
There is an effect that the waveguide microstrip converter itself becomes inexpensive.

[0039]

As described above, according to the present invention, the waveguide portion is divided into two parts by the plane perpendicular to the H plane at the central position of the H plane of the waveguide. Since the first and second waveguide main body portions are formed by using the same mold and have the waveguide main body portion, and are configured to be joined while holding the printed circuit board, It is easy to perform, and the cost can be reduced.

According to the present invention, since the insulating material of the printed circuit board is made of the resin material, there is an effect that the cost can be reduced.

According to the present invention, the printed circuit board is sandwiched between the first and second waveguide main body portions at its one end, so that the printed circuit board can be easily held.

According to the present invention, the second waveguide main body has the groove-shaped holding portion in which the one end of the printed circuit board is arranged on the joint surface with the first waveguide main body, and the holding portion holds the groove. Since the depth of the portion is smaller than the thickness of the printed circuit board and one end of the printed circuit board is crushed by the first waveguide body, the printed wiring board can be easily fixed. There is an effect.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a waveguide microstrip converter according to a first embodiment of the present invention.

FIG. 2 is a plan view of a joint surface between the upper portion of the waveguide shown in FIG. 1 and the lower portion of the waveguide seen from above.

3 is a sectional view taken along the line AA in FIG. 1 in a state in which the waveguide microstrip converter shown in FIG. 1 is assembled.

FIG. 4 is a view showing fixing of the printed circuit board to the RF module in a state where the upper portion of the waveguide is removed in the waveguide microstrip converter shown in FIG.

5 is an enlarged view showing a lower portion of the waveguide shown in FIG. 4 together with a printed circuit board.

6 is a diagram showing an example of a front end portion (insertion end portion) of the printed circuit board shown in FIG.

7 is a view showing a cross section taken along line BB after the waveguide microstrip converter shown in FIG. 1 is assembled.

FIG. 8 is a diagram for explaining the characteristics of the waveguide microstrip converter shown in FIG.

9 is a diagram showing the characteristics of the waveguide microstrip converter shown in FIG. 1 in the vicinity of 26 GHz.

10 is a diagram showing an example of an RF module using the waveguide microstrip converter shown in FIG.

FIG. 11 is a perspective view showing a conventional waveguide microstrip converter.

[Explanation of symbols]

10, 16 Flange, 10a, 10b, 16a, 16
b flange portion, 10c, 16c mounting hole, 11
Waveguide upper part (waveguide part), 11a Waveguide upper body part (first waveguide body part), 12 Waveguide lower part (waveguide part),
12a Lower waveguide main body (second waveguide main body), 13
Printed circuit board, 13a strip conductor, 13b insertion end, 13c rectangular pattern, 14 screw, 15
Short side, 15a, 15b Short side, 17 Screw hole, 18 Printed board insertion slot, 18a, 18b Printed board insertion slot, 19 Printed board holding section, 21
RF module, 22 screws, 30 circulator,
31 first waveguide microstrip converter (reception-system waveguide microstrip converter), 32 low noise amplifier, 33 first microstrip bandpass filter (BPF), 34 down converter, 35 local circuit, 35a , 35b microstrip line,
36 up converter, 37 2nd microstrip bandpass filter (BPF), 38 high power amplifier, 39 2nd waveguide microstrip converter (transmission system waveguide microstrip converter).

Claims (4)

[Claims] 1. A waveguide microstrip converter comprising: a waveguide section having a waveguide formed therein; and a printed circuit board having a microstrip line formed therein, which is inserted into the waveguide section. The waveguide section has first and second waveguide main body sections that are divided into two by a plane perpendicular to the H plane at a central position of the H plane of the waveguide. 2. The waveguide microstrip converter according to claim 1, wherein the waveguide main body is formed by using the same mold, and the waveguide main body is joined while holding the printed circuit board. 2. The waveguide microstrip converter according to claim 1, wherein the insulating material of the printed circuit board is made of a resin material. 3. The waveguide microstrip converter according to claim 2, wherein the printed circuit board is sandwiched between the first and second waveguide main body portions at one end thereof. 4. The second waveguide main body section has a groove-shaped holding section in which one end portion of the printed circuit board is arranged on a joint surface with the first waveguide main body section. 4. The waveguide microstrip conversion according to claim 3, wherein the depth is smaller than the thickness of the printed circuit board, and one end of the printed circuit board is crushed by the first waveguide body. vessel.