JPS642281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a waveguide-to-microstrip line converter, and in particular, an object of the present invention is to provide a waveguide-to-microstrip line converter having a structure with uniform performance during mass production. It is.

The structure of a conventional waveguide-to-microstrip line converter of this type is shown in FIG. 1, and its cross-sectional view is shown in FIG. This is done by attaching a microstrip line to the outer wall surface parallel to the H-plane of the waveguide 1, and installing the microstrip line at a position where the electrical length is around λg/4 from the short-circuit surface 2 of the waveguide 1 (here,
λg is the propagation wavelength in the waveguide), that is, S = λg/4
The probe conductor rod 3 and the probe insulator made of a dielectric material are inserted in the direction of the electric field of the electromagnetic wave propagating in the waveguide 1 at the position of Connection part 9-
At step b, the probe conductor rod 3 and the microstrip conductor 6 are connected by soldering.

The microstrip line is composed of a microstrip conductor 6, a dielectric plate 7, and a ground conductor 8, and the ground conductor 8 is located at a position where it joins the side wall of the waveguide.

The impedance matching plate 5 includes the probe conductor rod 3
and the microstrip conductor 6, and its dimensions a and b are based on the impedance of the microstrip line, the waveguide insertion length L of the probe conductor rod 3, and the short-circuit surface 2. It varies depending on the distance S, the diameter of the probe conductor 3, and the dielectric constant of the probe insulator, and is determined experimentally.

By the way, the electrical performance of a waveguide-microstrip converter is expressed by VSWR. In other words, it is good for the VSWR to be close to 1 over a wide frequency band. FIGS. 3 and 4 are examples of conversion characteristics between a microstrip line using a 12 GHz band waveguide, a dielectric plate made of a Teflon (registered trademark) substrate, and a characteristic impedance of 50Ω. FIG. 3 shows an example of the characteristics with dimensions S=6 mm, a=4 mm, b=3 mm and the insertion length L of the probe conductor rod 3 as a parameter. Also, in Figure 4, S = 6 mm, L = 4 mm, b
= 3 mm, and the length a of the impedance matching plate 5 is used as a parameter.

From the above characteristic examples, it can be seen that the VSWR characteristics of a waveguide-microstrip line converter are greatly influenced by the dimensions of the constituent parts. 11GHz~
If a VSWR of 1.2 or less is required in the 12 GHz band, at least the probe conductor insertion length L and the impedance matching plate length a must have dimensional accuracy sufficiently smaller than 1 mm. Furthermore, it is estimated from the above characteristic examples that changes in the width b of the impedance matching plate 5, the dimensions of the probe insulator, the dielectric constant ε, etc. similarly greatly affect the VSWR characteristics, and similar dimensional accuracy and uniformity are required. It actually has a big impact.

However, in the structure according to the conventional example, even if the dimensional accuracy of each constituent part is good, unevenness occurs in the assembly in the conductor connection part 9-a. That is, there are effects due to uneven probe insertion length L, solder build-up at the conductor connection part 9-a, and changes in distributed capacitance near the soldering due to thermal deformation of the probe insulator due to heat during soldering. The same effect as when changing the dimensions of the impedance matching plate is produced,
It had the drawback of poor reproducibility of VSWR characteristics. The probe insulator is made of heat-resistant materials such as polyethylene or polystyrene because of its good workability.

The present invention eliminates the above-mentioned drawbacks and provides a waveguide with a structure that has reproducibility of VSWR characteristics, that is, mass production.
It is intended to provide a microstrip line transducer, and embodiments of the present invention will be described below. Components that are the same as those in FIGS. 1 and 2 are given the same numbers and their explanations will be omitted.

The waveguide-microstrip converter according to the present invention has an impedance matching plate portion and a probe conductor portion formed by bending a single plate, or
By using a pre-integrated probe matching element in which a probe conductor with a flange is inserted and bonded in advance to an impedance matching plate, the number of solder joints is reduced and the assembly dimensions and electrical reproducibility are improved. It has the following.

FIG. 5 shows an embodiment of the present invention. The impedance matching plate and probe conductor rod shown in FIG. 1 are replaced by a probe matching element 11, and a probe insulator made of a hollow dielectric is fixed to the waveguide wall.

As shown in FIGS. 6a and 6b, the probe matching element 11 is constructed by folding a single conductive plate into an L-shape, which has a wide part serving as an impedance matching plate part and a narrow part serving as a probe conductor rod part. It is curved and made with good dimensional accuracy by punching or etching and simple bending. The probe insulator 12 fixes the waveguide insertion part 13 of the probe matching element 11, and is a hollow dielectric body having a circular or square guide hole in the center.

In the assembly work of the embodiment of the present invention, since the work of soldering the probe conductor rod is eliminated, the structure has very high dimensional and electrical reproducibility and is suitable for mass production.

Figure 7 shows the VSWR characteristics of the waveguide stripline converter according to the same example.
It has good performance with VSWR of 1.25 or less at 11.3GHz to 12.5GHz.

FIG. 8 shows a second embodiment in which a flangeed probe conductor rod 14 is inserted into an impedance matching plate 5 to form an L-shape, and is bonded in advance to form a probe matching element 11.

In order to avoid thermal deformation of the probe insulator 4, the desired purpose can be achieved by connecting the flangeed probe conductor to an impedance matching plate in advance, but if the impedance is Since the matching plate is extended, the flangeed probe conductor rod 14 needs to be longer than in the first embodiment.

As described above, the waveguide-microstrip converter according to the present invention does not deteriorate in performance due to mass production and can be provided at low cost.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventional waveguide-microstrip line converter, Fig. 2 is a sectional view thereof, Figs. 3 and 4 are characteristic diagrams of the converter, and Fig. 5
The figures are a cross-sectional view of a waveguide-microstrip line converter according to an embodiment of the present invention, FIG. 6 is a perspective view for explaining the probe matching element of the converter, and FIG.
The figure is a characteristic diagram of an embodiment according to the present invention, and FIG. 8 is a perspective view of a probe matching element of another embodiment. DESCRIPTION OF SYMBOLS 1... Waveguide, 4... Probe insulator, 5... Impedance matching plate, 6... Microstrip conductor,
11... Probe matching element, 13... Waveguide insertion part,
14...Probe conductor rod with flange, 9...Conductor connection part.

Claims (1)

[Claims] 1 H of a waveguide whose one end in the transmission direction is short-circuited
A microstrip line is provided on the outer wall surface parallel to the waveguide, and an insertion hole is provided at a position λg/4 (where λg is the propagation wavelength in the waveguide) from the short-circuit surface of the waveguide. , a probe matching element is used in which a probe conductor rod part and an impedance matching plate part are integrated in an L-shape in advance, and the probe conductor rod part and a hollow dielectric probe insulator fitted therein are used. is inserted into the insertion hole and inserted into the waveguide in the direction of the electric field of the propagating electromagnetic wave, and the impedance matching plate is connected to the microstrip conductor of the microstrip line on the microstrip line. Connected waveguide-microstrip line conversion path. 2. The waveguide-microstrip line conversion according to claim 1, wherein the probe matching element is constructed by bending a single conductor plate having a narrow portion into an L shape. vessel. 3. The waveguide-microstrip according to claim 1, wherein the probe matching element is constructed by inserting a probe conductor rod with a flange into an impedance matching plate and joining them in advance to integrate them. line converter.