KR100764604B1 - Non-Radiated Microstrip Lines with Ground Plate - Google Patents

Abstract

The present invention relates to a transmission line for use in microwave and millimeter wave bands. In particular, a strip line of copper foil is fabricated by a photoetching technique on a dielectric substrate, and a ground plate is placed at upper and lower portions of the substrate at regular intervals to radiate radio waves. The present invention relates to a non-radiative microstrip line using a method of preventing the occurrence of a high order mode and preventing the occurrence of higher order modes. The non-radiative microstrip line is made of copper foil microstrip lines on a thin dielectric substrate, and the width Wm of the ground jig plate, the width Wg of the ground copper foil pattern, and the gap Wd between the strip line and the ground copper foil pattern. The line impedance is adjusted accordingly; Through-holes are drilled through the left and right ground copper foil patterns of the strip line, and the through-hole spacing is processed to less than half the wavelength (1 / 2λ) of the operating frequency. The dielectric under the strip operates as a substrate, and the left and right ground copper foil patterns of the strip line act as metal plates due to the through holes, thereby preventing electromagnetic waves from radiating and reducing transmission loss. In this case, a similar TEM mode is formed which is very similar to the TEM. Unlike quasi-TEM of conventional microstrip line, this similar TEM mode is closer to TEM mode, which makes RF passive and active circuit configuration easier, and can be used in millimeter wave band.

Non-Radiated Microstrip Line, Ground Plate, Through Hole

Description

Non-Radiative Microstrip Line with Ground Pattern}

1: Structure of non-radioactive microstrip line

2: Main parameters of non-radiative microstrip line structure

3 to 17: Transmission characteristics of the main parameters of the structure of the non-radiative microstrip line

18: Smith chart for S-parameters on non-radioactive microstrip line

19 and 20: Electromagnetic field distribution diagram of non-radiative microstrip line

<Detailed Description of Details>

10: upper ground jig plate, 11: lower ground jig plate, 12: copper box trip line, 13: dielectric substrate, 14: copper foil pattern for ground plate of dielectric substrate, 15: through hole

In general, in order to manufacture an ultra high frequency circuit, a line having a low transmission loss is required at an ultra high frequency. In particular, the microstrip line is the most popularly used.

In the microstrip line method, the microstrip line is a structure in which a dielectric is located between the lower ground metal plate of the transmission line and the top of the transmission line is open, and it is used for manufacturing almost all high frequency circuits, printing methods and photoresistors. It can be easily manufactured by the photo resistor method, so it is easy to attach / detach components such as resistors, capacitors, and semiconductors, so that an RF active circuit can be realized.

However, open microstrip lines have a problem in that transmission loss increases due to generation of a hybrid mode that cannot be ignored when transmitting a frequency of 10 GHz or more.

In addition, since the open microstrip line is transmitted in quasi-TEM mode, when the SMA connector is attached, a mode conversion occurs between quasi-TEM mode and TEM mode, and thus matching loss occurs.

In addition, when the RF circuit is implemented, transmission lines are patterned in various shapes such as bending or distributing lines as well as straight sections, resulting in higher order modes causing large transmission loss, or increasing transmission losses due to leakage waves. The amplification circuit configuration is difficult because amplification of signals in the wave band is not easy.

Complements the disadvantages of the conventional ultra-high frequency lines described above, and is easy to configure the RF circuit in the microwave or more millimeter wave band, freely detachable shape of the semiconductor components, such as photo-etching pattern, and easy transmission loss The present invention aims to develop a non-radiative microstrip line that has a very wide transmission frequency band and is easy to manufacture such as a microstrip and does not cause any loss in bending or the like.

In the present invention, a strip line of copper foil is made by photoetching or the like on a dielectric substrate, spaced at regular intervals on the top / bottom and left / right, and then a ground jig plate is placed to prevent radiation of radio waves. In particular, if a microstrip line of copper foil is made on a thin dielectric substrate, spaced at regular intervals on the top / bottom and left / right, and then the ground plate is placed, the field mode causes a TEM mode very similar to the TEM.

In addition, a through hole is drilled through the ground plate copper foil pattern 14 for the left and right of the dielectric substrate, and the distance of the through hole is processed to be equal to or less than half wavelength (1 / 2λ) of the use frequency. At this time, the dielectric under the strip, which is an internal transmission line, acts as a substrate, and the left and right ground plate copper foil patterns 14 of the strip line act as metal plates due to the through holes, thereby radiating electromagnetic waves due to leakage waves. Prevent and reduce transmission loss.

The pseudo TEM mode formed at this time has a very different shape from quasi-TEM of the existing microstrip line. quasi-TEM has an asymmetrical electromagnetic field mode in which the electric field / magnetic field mode occurs only between the ground plate below and the strip line above, so that the electric field mode does not exist at the part contacting the air on the strip, but in this non-radiated microstrip line In the upper and lower ground plates of the strip, the magnetic field distribution is the same, resulting in a similar TEM mode almost identical to that of the TEM.

In this pseudo TEM mode, when combined with the conventional TEM mode, the mode conversion does not occur, so the coupling loss is hardly generated, the actual insertion loss is close to zero, and the return loss is also lowered to -30dB, indicating no loss. In addition, if the distance between the ground jig plate located at the top / bottom and the left / right is within the half wavelength (1 / 2λ) of the frequency to be transmitted, a lossless line can be made.

The principle of the non-radiating microstrip line is that if the distance between the ground plate of the upper and lower sides is a, a is within half wavelength (1 / 2λ) of the transmission frequency, and the interval between the left and right ground jig plate is b, If b is also within the half-wavelength (1 / 2λ) of the transmission frequency, the TEM waves traveling along the strip line are already half-wavelength even if the band is changed to TE or TM mode when the strip is bent or opened. Since it is within 1 / 2λ), mode conversion is suppressed so that a higher order mode does not occur, and it is possible to confirm that all the signals are returned to the input port because no radio waves are radiated at the open line. No progress is made along the banding microstrip line without loss.

In the present invention, the non-radiative microstrip line is produced on the dielectric substrate 13, the strip line 12 of copper foil by a photoetching technique, etc., the ground jig plate 10 having a predetermined interval on the line up / down and left / right. , 11), through-hole 15 is drilled in the ground plate copper foil pattern 14 on the left and right of the dielectric substrate, and the through-hole 15 is cut below half wavelength (1 / 2λ) of the operating frequency along the strip line. do. At this time, the dielectric under the strip, which is an internal transmission line, acts as a substrate, and the left and right ground plate copper foil patterns 14 of the line operate as metal plates due to the through holes 15 to prevent electromagnetic waves from being emitted, and to prevent leakage waves. The effect of suppressing the occurrence of is obtained.

Figure 1 shows the structure of the non-radiating microstrip line. In Fig. 1, a non-radiative microstrip line is made of copper foil strip line 12 and ground plate copper foil pattern 14 on a thin dielectric substrate 13, and spaced at regular intervals on the top / bottom and left / right. Next, the ground jig plates 10 and 11 are arranged.

Preferably, the through hole 15 is drilled in the ground plate copper foil pattern 14 for the left and right of the dielectric substrate, and the gap between the through holes 15 is processed below the half wavelength (1 / 2λ) of the operating frequency along the strip line. The dielectric under the strip, which is the transmission line, acts as a substrate, and the copper foil pattern 14 for the left and right ground plates of the strip line acts as a metal plate due to this through hole 15.

2 is a diagram showing the main parameters of the structure of the non-radiative microstrip line. In Fig. 2, a denotes an interval between the upper and lower ground jig plates 10 and 11, b denotes an interval between left and right ground jig plates 10 and 11, and Wm denotes a ground jig plate 10 and 11. And the width where the copper foil pattern 14 for the ground plate abuts, Wg is the width of the copper foil pattern 14 for the ground plate to obtain the metal plate effect, Wd is the distance between the strip line 12 and the ground plate, Wl is the width of the strip line 12 And t represent the thickness of the dielectric substrate 13.

Preferably, the spaces a and b of the upper and lower and left and right ground jig plates 10 and 11 and the width Wl of the strip line, and the width Wm of the ground jig plates 10 and 11 and the copper foil pattern 14 for the ground plate abut on each other. The line impedance is adjusted by the width Wg of the copper foil pattern for the ground plate and the spacing Wd between the strip line 12 and the ground plate.

3 shows a transmission loss of a line when a is 1 mm, Wm is 1 mm, Wd is 1 mm, and Wg is 0 mm in the non-radiative microstrip line structure. At this time, the thickness of the dielectric substrate is 0.15 mm. In FIG. 3, the above structure shows excellent transmission characteristics within an insertion loss of -1 dB and a reflection loss of -40 dB to a 60 GHz band.

4 shows a transmission loss of a line when a non-radiative microstrip line structure has a 1 mm, W m 1 mm, W d 1 mm, and W g 1 mm. At this time, the thickness of the dielectric substrate is 0.15 mm. In FIG. 3, the above structure shows excellent transmission characteristics within an insertion loss of -0.5 dB and a return loss of -30 dB from 10 GHz to 100 GHz.
The characteristics as such a transmission line can be seen in Table 1 below. The data shown in Table 1 shows the transmission frequency band characteristic of -1dB of transmission loss through changing the interval of a to 1-3 in the above line.
S21 -1dB loss bandwidth (transmission characteristics comparison table) Upper / Lower Ground Plate Gap (mm) One 2 3 Pass frequency Bandwidth (GHz) Pass frequency Bandwidth (GHz) Pass frequency Bandwidth (GHz) Ground track 1-200 GHz 200 1-132 GHz 132 1-147 GHz 147

Preferably, the distance a between the upper and lower ground jig plates 10 and 11, the width Wm where the ground jig plates 10 and 11 and the ground plate copper foil pattern 14 abut, the width Wg of the ground plate copper foil pattern, and the strip line ( The transmission loss characteristics of the strip line 12 according to the change of the distance Wd between the ground plate 12) and the ground plate are shown in Figs.

In the present invention, the space a between the upper and lower ground jig plates 10 and 11 and the space b between the left and right ground jig plates 10 and 11, the ground jig plates 10 and 11 and the copper foil pattern 14 for the ground plate. It can be seen that the line impedance of the strip line 12 can be adjusted by adjusting the width Wm a), the width Wg of the copper foil pattern 14 for the ground plate, the spacing Wd between the strip line 12 and the ground plate.

18 is a diagram showing an S-parameter Smith chart for changes in a, Wm, Wd, and Wg. 18 (a) shows a line impedance of 55.73 ohms when a is 1mm, Wm is 1mm, Wd is 1mm, and Wg is 0mm, (b) a is 1mm, Wm is 1mm, Wd is 1mm, and Wg is At 1mm, the line impedance is 56.76 ohms.

In the present invention, the half-wavelength (1 /) of the maximum frequency to which the interval a between the ground jig plates 10 and 11 located above and below and the interval b between the ground jig plates 10 and 11 located at the left and right sides are to be transmitted. If it is within 2λ), it becomes a lossless line. In particular, if the distance between the two ground jig plates 10 and 11 located at the top / bottom and the left / right is a and b, the a and b are within the half wavelength (1 / 2λ) of the transmission frequency, along the strip line 12. Progressive TEM waves are already half-wavelength (1 / 2λ) at the time of banding or opening the strip, so the higher order mode does not occur, all of them are returned on the open line, and the band on the bending line. Proceed without loss along the microstrip line. In this case, a similar TEM mode is formed which is very similar to the TEM.

The TEM mode has a shape very different from quasi-TEM of a conventional microstrip line. Conventional qusai-TEM has an asymmetrical electromagnetic field mode in which the electric field / magnetic field mode occurs only between the ground plate and the upper strip line, so that the electric field mode does not exist in the part contacting the air on the strip, but the non-radiative method of the present invention The microstrip line has the same magnetic field distribution on the upper and lower ground plates of the strip, and generates a similar TEM mode almost identical to that of the TEM.

Preferably, the upper / lower and left / right ground plates are filled with air, and the thin dielectric substrate 13 is made of a similar TEM mode in which the microstrip line transfer mode is very similar to that of the TEM, and uses a TEM mode such as a connector. It is easy to connect with components or circuits, so that no mode change occurs and hardly any coupling loss occurs.

FIG. 19 and FIG. 20 show the distribution diagrams of the electromagnetic field modes for the changes of a, Wm, Wd, and Wg. In FIG. 19, a represents 1 mm, W m represents 1 mm, W d represents 1 mm, and W g represents 0 mm. In FIG. 20, a is 1mm, Wm is 1mm, Wd is 1mm, and Wg is 1mm, indicating the electromagnetic field distribution. In the above structure, it can be seen that it has a mode almost similar to the conventional TEM mode.

As described above, the non-radiative microstrip line of the present invention has the same characteristics as those having a wavelength less than half wavelength (1 / 2λ) of the interval between the upper / lower and left / right ground jig plates 10 and 11, and thus have the same characteristics. Since it does not radiate out of the line, there is almost no transmission loss, and as the conventional microstrip substrate is easily attached and detached, the circuit manufacturing is simple.

Further, the ground jig plates 10 and 11 are placed at the upper, lower, left and right sides of the strip line 12 at regular intervals, and the width Wl of the strip line and the ground jig plates 10 and 11 and the copper foil pattern 14 for the ground plate. It was found that the line impedance can be adjusted by adjusting the width Wm a) contacted, the width Wg of the copper foil pattern 14 for the ground plate, and the distance Wd between the strip line 12 and the ground plate.

In addition, since the internal electromagnetic mode is similar to the TEM, similar to the TEM, there is almost no mode conversion loss with the device, the circuit, and the connector using the conventional TEM mode, thereby making an excellent circuit. Therefore, the non-radiative microstrip line may be used as an optimal transmission line for the fabrication of RF active circuits and passive circuits at frequencies ranging from microwave and millimeter wave bands.

In addition, a through hole was drilled through the copper foil pattern 14 for the upper and lower ground plate of the dielectric substrate located at the left and right of the strip line, and the through hole spacing was processed to less than half wavelength (1/2 lambda) of the use frequency. This is because the dielectric under the strip, which is an internal transmission line, acts as a substrate, and the left and right ground plate copper foil patterns 14 of the strip line act as metal plates due to these through holes, preventing electromagnetic radiation from leaking waves and transmitting loss. It is possible to implement a line that achieves a lossless transmission characteristic with a broadband transmission characteristic of 1 GHz to 100 GHz or more.

Claims (5)

In a non-radioactive microstrip line structure having a ground plate, A strip line 12 of copper foil is fabricated on the dielectric substrate 13 by a photoetching technique or the like; Half-wavelength of the maximum frequency to use the gap a between the top / bottom gap a of the ground jig plates 10 and 11 disposed above and below the strip line 12 and the gap b between the left and right ground jig plates 10 and 11. To within (1 / 2λ); A strip line 12 having a width Wl is formed on the dielectric substrate 13 by etching or printing; A copper foil pattern 14 for a ground plate is formed on the part of the strip line 12 on the dielectric substrate 13 in contact with the ground jig plates 10 and 11 on the left and right sides by etching or printing; Through-holes 15 are processed in the air layer portions inside the ground jig plates 10 and 11 of the ground plate copper foil pattern 14; Non-radiative microstrip line with ground plate, characterized in that through-hole 15 is processed continuously along the strip line 12 through The method of claim 1, In order to determine the use frequency of the non-radiative microstrip line with the ground plate, the upper and lower intervals a and the left and right ground jig plates of the ground jig plates 10 and 11 disposed above and below the strip line 12 ( 10, 11) within the half-wavelength (1 / 2λ) of the maximum frequency to be used, and the non-radiating with a ground plate characterized by adjusting the thickness t of the dielectric substrate and the width Wl of the strip line 12 Microstrip Line The method of claim 1, In order to adjust the impedance of the non-radiating microstrip line with the ground plate, the distance a between the upper and lower ground jig plates and the distance b between the left and right ground jig plates, the width Wl of the strip line 12, and the strip line 12 Non-radioactive microstrip line with ground plate characterized in that it is controlled by the distance Wd and the through-hole 15 and the width Wg of the through-hole The method according to any one of claims 1, 2 and 3, When the through hole 15 is processed in the ground plate copper foil pattern 14 for etching or printed on the left and right sides of the dielectric substrate 13, the position is processed in the air layer portion inside the ground jig plates 10 and 11, or The ground plate, which is machined on the part which is in contact with the ground jig plates 10 and 11, and when the through hole is continuously processed along the strip line, the distance is within half wavelength (1 / 2λ) of the maximum operating frequency. Radiated Microstrip Lines The method of claim 4, wherein A ceramic filter circuit made by inserting a ceramic resonator between the strip lines 12 etched or printed in the ground jig plates 10 and 11; An amplifier circuit for inserting an MMIC semiconductor element between strip lines 12 etched or printed in the ground jig plates 10 and 11; Non-radiative with a ground plate, characterized in that the isolator circuit and circulator circuit made by placing a ferrite disk and a magnet on the top and bottom of the strip line 12 etched or printed in the ground jig plate (10, 11) Microstrip Line

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