JPH0321043Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a microstrip line type distributor that is capable of correcting the center frequency.

(Prior Art) In recent years, with the increase in communication capacity, the digitalization of wireless communication has progressed, and many digital wireless communication devices are being used. As a digital modulation/demodulation circuit, a four-phase phase modulation circuit is widely used because it has relatively high frequency utilization efficiency, low code error rate, and does not require a large circuit size.

Here, a circuit diagram of a four-phase phase demodulator is shown in FIG. In FIG. 2, a four-phase phase modulation signal applied to an input terminal 21 is divided into two signals having the same level and the same phase by a distributor 22, and the two signals are applied to two phase detectors 23 and 24. Further, the carrier wave applied to the carrier wave input terminal 25 is converted by the phase shifter 29 into two signals having a phase difference of 90 degrees,
The two phase detectors 23 and 24 are respectively provided with the same signal. The output signals of these phase detectors 23 and 24 are applied to an identification reproducing circuit (not shown) from output terminals 27 and 28, respectively, and demodulated into two data signals, an I signal and a Q signal.

By the way, if the carrier wave of the four-phase phase modulation signal is in the microwave band, a circuit formed of microstrip lines is often used in the configuration of the four-phase phase modulator/demodulator. FIG. 3 shows a circuit diagram formed of microstrip lines of the distributor 22 constituting the above-mentioned four-phase demodulator. In FIG. 3, one end of a first microstrip line 32 is connected to an input terminal 31, and one end of two second microstrip lines 33 and 34 are connected to the other end of the first microstrip line 32, respectively. The other ends of these two second microstrip lines 33, 34 are connected via a resistor 35, and are connected to an output terminal 38 via third microstrip lines 36, 37, respectively. ，
It is connected to 39. The characteristic impedances of the first and third microstrip lines 32, 36, 37 are equal to ZΩ, and are set equal to the impedance of the circuit connected to the input/output terminals 31, 38, 39 in order to obtain matching. There is. The characteristic impedance of the second microstrip lines 33 and 34 is √2.ZΩ, and the length thereof is set to 1/4 of the wavelength of the center frequency of the input signal. Furthermore, the impedance of the resistor 35 is set to 2.ZΩ. As an example, if the characteristic impedance of the first and third microstrip lines 32, 36, 37 is 50Ω, the characteristic impedance of the second microstrip lines 33, 34 is
Set the impedance of resistor 35 to 100Ω to 70.7Ω.
Set each.

(Problems to be solved by the invention) In the case of the distributor 22 formed of microstrip lines shown in FIG. 35
Due to errors in the mounting position of the second microstrip line 3 and variations in the permittivity of the dielectric substrate on which the microstrip line 3 is formed,
3,34 is not 1/4 of the wavelength of the predetermined frequency,
There is a problem that the center frequency of the distributor 22 tends to shift.

By the way, the performance of the four-phase demodulator shown in FIG. 2 is required to be 20 dB or more in both return loss and isolation. The frequency band of the distributor 22 that can satisfy such performance is a theoretical fractional bandwidth of 0.3 to 0.35, and if the center frequency is set to _600MH
The bandwidth is 700MH _Z and the center frequency is
If it is _1500MHZ , it is a bandwidth of 1250 to _1800MHZ . However, in the divider 22 shown in FIG. 3, the actual center frequency tends to deviate by about 0.1 in the fractional bandwidth from the design value, and the fractional bandwidth that can actually be used is 0.2 to 0.25, which is 550 to _650MHZ , 1400MHz. ~
The bandwidth is narrow at 1650MH _Z.

Note that if the bandwidth used by the distributor 22 is widened,
Return loss and isolation worsen for frequencies near the lower and upper limits of the band. If the isolation of this distributor 22 deteriorates,
The signals given from the phase shifter 29 to the phase detectors 23, 24 flow back to the distributor 22, and then mutually flow into the other phase detectors 23, 24, resulting in the data signal demodulated by the identification reproducing circuit. This causes a problem that the code error rate increases.

Therefore, it is desired that the shift in the center frequency of the distributor 22 can be easily corrected. However, the conventional distributor 22 formed of microstrip lines shown in FIG. 3 is not provided with an adjustment mechanism, and the center frequency cannot be adjusted.

The purpose of the present invention was to solve the problems of the conventional microstrip line type distributor mentioned above, and by making it possible to correct the center frequency,
It is an object of the present invention to provide a microstrip line type distributor which allows a wide usable bandwidth.

(Means for Solving the Problems) In order to achieve the above object, the microstrip line type distributor of the present invention has a first microstrip line with a characteristic impedance of ZΩ that forms a signal path. At one end, the characteristic impedance √2・
In a microstrip line type divider that connects two second microstrip lines of ZΩ and divides an input signal into two and outputs the two, one end of the first microstrip line is divided into two. Branched out and said 2
In addition to connecting the two second microstrip lines, the two second microstrip lines form a proximal part in which the two second microstrip lines are close to and parallel to each other at this branching part, and further the two second microstrip lines are connected to each other. By making the strip line slightly longer than 1/4 of the wavelength of the predetermined frequency and soldering the adjacent portion,
The electrical length of the two second microstrip lines is adjusted.

(Function) One end of the first microstrip line is branched into two to connect two second microstrip lines, and at this branch, the two second microstrip lines are connected. Having formed adjacent parts that are close and parallel to each other, the electrical length of the two second microstrip lines can be adjusted by appropriately soldering the adjacent parts. The center frequency of the distributor can be adjusted to a desired frequency to match 1/4 of the wavelength of a predetermined frequency.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to FIG. FIG. 1 is a structural diagram of an embodiment of the microstrip line type distributor of the present invention.

In FIG. 1, the input terminal 1 is connected to one end of a first microstrip line 2 to form a signal path, and the other end of the first microstrip line 2 is branched into two to form two second microstrip lines 3, 4 and connect
At this branching point, the two second microstrip lines 3, 4 form a parallel part close to each other at a distance of d. The other ends of these second microstrip lines 3 and 4 are connected via a resistor 5, and are connected to output terminals 8 and 8 via third microstrip lines 6 and 7, respectively. 9
It is connected to the. The characteristic impedances of the first and third microstrip lines 2, 6, and 7 are equal to ZΩ, and the second microstrip lines 3,
The characteristic impedance of resistor 4 is √2·ZΩ, and the impedance of resistor 5 is 2·ZΩ. Furthermore, the length of the second microstrip lines 3 and 4 is formed to be slightly longer than 1/4 of the wavelength of the desired center frequency. The specific dimensions of the first, second, and third microstrip lines 2, 3, 4, 6, and 7 are as follows: the dielectric substrate has a dielectric constant of 4.5, a thickness of
When a 0.8 mm glass epoxy substrate is used and the characteristic impedance Z = 50Ω, the line widths of the first and third microstrip lines 2, 6, and 7 are as follows.
The line width of the second microstrip lines 3 and 4 is 0.7 mm. Then, the distance d of the adjacent part is
If it is 0.2 mm, the line width of the branch part is 1.6 mm.

In such a configuration, solder 10 is applied between the adjacent parts.
, and the electrical lengths of the two second microstrip lines 3 and 4 are shortened by the buried length. In this way, the electrical length of the second microstrip lines 3 and 4 is made to match 1/4 of the wavelength of the desired center frequency by the solder 10, and the distributor 2
The center frequency of 2 can be adjusted to a predetermined frequency. Note that the line width of the branched portion to which the solder 10 is attached is 1.6 mm and the characteristic impedance is 48Ω, and by forming the branched portion and adjusting the adhesion of the solder 10, return loss is not worsened.

(Effects of the invention) As explained above, according to the microstrip line type distributor of the present invention, the electricity of the two second microstrip lines can be changed by appropriately soldering the adjacent parts. Since the electrical length can be adjusted, the center frequency of the distributor can be adjusted to a desired frequency by matching this electrical length to 1/4 of the wavelength of a predetermined frequency. Therefore, the frequency band of the distributor can be widened with a simple configuration and easy adjustment. Further, it is possible to realize a four-phase phase demodulator with excellent isolation and return loss, and a low bit error rate.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of an embodiment of the microstrip line type distributor of the present invention, and FIG.
FIG. 3 is a circuit diagram of a phase demodulator, and FIG. 3 is a circuit diagram of a divider formed by a conventional microstrip line. 2: First microstrip line, 3, 4:
Second microstrip line, 10: solder.

Claims (1)

[Scope of utility model registration request] Two second microstrip lines with a characteristic impedance of √2 ZΩ are connected to one end of the first microstrip line with a characteristic impedance of ZΩ forming a signal path, and the input signal is divided into two. In the microstrip line type divider that outputs the microstrip line, one end of the first microstrip line is branched into two, the two second microstrip lines are connected, and this branch The two second microstrip lines are close to each other to form a parallel adjacent section, and the two second microstrip lines are formed to have a length slightly longer than 1/4 of the wavelength of a predetermined frequency. A microstrip line type distributor characterized in that the electrical length of the two second microstrip lines is adjusted by soldering the adjacent portions.