KR20040036021A - PCB Coaxial Connector - Google Patents

Abstract

PURPOSE: A coaxial connector for coupling a microwave transmission line is provided to receive a central conductor inside, and to fill a portion of the central conductor with a dielectric as filling another portion with the air, then to improve transition characteristics with a transmission line, thereby realizing excellent electric and high frequency characteristics. CONSTITUTION: A connector body(10) forms an outer shape and a housing of a connector. A central conductor(13) has the first terminal(14) and the second terminal(15) opposite to each other. A dielectric(12) electrically separates the connector body(10) from the central conductor(13), and determines impedance of the connector. The central conductor(13) is received inside the connector body(10). A portion of the central conductor(13) is filled with the dielectric(12), and other portion thereof is filled with the air. A diameter of the central conductor(13) stepwise changes as going toward the second terminal(15) from the first terminal(14). A diameter of the second terminal(15) is smaller than that of the central conductor(13).

Description

Coaxial connector for joining microwave transmission line {PCB Coaxial Connector}

The present invention relates to a coaxial connector for a high frequency transmission line. More specifically, the inside of the connector accommodates a central conductor, and part of the connector is filled with air, and part of the connector is filled with air. The present invention relates to a microwave coaxial connector which is self-improved.

Most microwave applications use coaxial transmission lines, which consist of a center conductor and an outer conductor. The center conductor and the outer conductor are separated by an electrically insulating dielectric.

Recently, as the coaxial transmission line is actively used in the field of wireless communication, the frequency of the signal transmitted through the coaxial transmission line is very high, such as 18 kHz or 26.5 kHz, and the electrical characteristics required for the connector of the coaxial transmission line become strict. In particular, if frequent insertion and disconnection of the connector is required, for example, when testing microwave devices, the electrical connection should be rapid, but the voltage standing wave radio (VSWR) must be low and the electrical isolation characteristics must be excellent. Accurate impedance matching must be ensured, and signal integrity and propagation characteristics are required.

Conventional coaxial connectors have a large center conductor that is difficult to bond to small, thin, high frequency substrates, and degrades above 10 Hz. In order to solve the fundamental problem of deteriorating characteristics during transition with transmission lines, connectors have been developed in which only the size of the coaxial connector center conductor ends or the shape of tabs are deformed to meet the low loss high frequency transmission line as the frequency increases. This requires an overall structural modification of the coaxial connector. However, the more structural deformation, the higher the reflection loss and the difficulty of meeting manufacturing difficulties or manufacturing tolerances.

It is an object of the present invention to provide a coaxial connector which is excellent in electrical characteristics, in particular in high frequency characteristics.

Another object of the present invention is to provide a coaxial connector having a simple structure and an easy manufacturing process.

It is still another object of the present invention to provide a coaxial connector having excellent insertion loss and reflection characteristics at a very high frequency of 10 Hz or more.

It is still another object of the present invention to provide a coaxial connector suitable for exporting signals to the outside via a microwave module package or a PCB transmission line.

1 is a cross-sectional view of a connector according to an embodiment of the present invention.

2 is a cross-sectional view of a connector according to another embodiment of the present invention.

3 is a cross-sectional view illustrating a state in which two connectors of the structure of FIG. 2 are connected to a PCB transmission line.

4 is a result of measuring the transition characteristics in the state connected as shown in FIG.

<Description of Major Symbols in Drawing>

10: outer conductor 11: fastening means

12: dielectric 13: center conductor

14: first terminal 15: second terminal

16: modified second terminal 17: air

18: Microstrip Transmission Line

The present invention relates to a coaxial connector that maintains a predetermined impedance while gradually decreasing the inner diameter of the center conductor and the outer conductor. The connection structure for high frequency signal transmission according to the present invention, the connector and the center body having a first terminal and a second terminal facing each other and the connector body forming the housing and the housing and electrically separating the connector body and the center conductor It is made of a dielectric to determine the impedance of the center conductor is accommodated inside the connector body, part is filled with a dielectric, part is made of air, the diameter of the center conductor in each section from the first terminal to the second terminal And vary in stages, the diameter of the second terminal being smaller than the diameter of the central conductor. In addition, the section where the diameter of the center conductor starts to change varies from the section where the material inside the connector body is air, and the point where the diameter starts to decrease when the diameter of the second terminal of the center conductor is reduced is referred to as a, and After assuming the position c, let d be the distance between a and c. The condition within 0.5mm is satisfied. According to the present invention, by using air in a part of the connector, the internal diameter of the connector body is reduced while minimizing the change in the diameter of the center conductor, the impedance is maintained, and the dielectric loss is reduced, thereby having more stable transmission characteristics in the high frequency region. In addition, by reducing a part of the second terminal to a diameter of 0.1mm ~ 0.7mm size and giving the interval d has the effect of having excellent transmission characteristics by reducing the parasitic component itself when the connector and the transmission line is connected.

Example

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing a coaxial connector connecting structure according to the present invention.

The coaxial connector includes a body 10, a dielectric 12 and a center conductor 13. The coaxial connector of FIG. 1 is, for example, a Sub-Miniature Series A (SMA) 2.92 mm or 3.5 mm female connector. The SMA interface conforms to, for example, MIL-C-39012 International Standard, and is used for high frequency devices such as wireless communication equipment and test instruments. It is used to carry a high frequency signal of 18 kHz or 26.5 kHz. However, the fact that the present invention is not limited to the type of the connector is not only SMA, but can be widely applied to the microwave connector will be easily understood by those skilled in the art. For example, the present invention may be applied to an N series connector, a TNC connector, a BNC connector, an F series and a G series connector, and the present invention may be a DIN connector, an OSMP connector, an SMB connector, an MCX connector, an SSMT connector, an OSMT connector, an MMXC connector, or the like. Can be widely used. Also available are 90 degree right angled connectors, semi rigid or semi flexible coaxial with 0.141, 0.250, 0.0856, 0.141, RG316, RG188, 1 / 2``, 7/8 ''. The present invention can also be applied to cables.

The body 10 of the connector is made of brass or other non-ferrous metal, and may be plated with gold or white bronze or the like. The connector body 10 is provided with a fastening means 11. In Figure 1, the fastening means 11 is implemented in the form of a screw, but is not limited to this, for example, may be implemented in a plug structure.

The center conductor 13 is surrounded by a dielectric 12. The body 10 formed outside the dielectric 12 may be electrically connected to an outer conductor (not shown) of the coaxial cable. The outer conductor is used for grounding and the center conductor 13 is usually used for transmitting microwave signals and the second terminal of the center conductor 13 is connected to the transmission line. A variable that defines the characteristics of a signal propagation structure, such as a cable or a connector, is called a characteristic impedance. The maximum energy is delivered if the impedances are the same between the two media through which the signal propagates, i.e., if there is an impedance match. On the other hand, if the impedance change is shorter than the wavelength, the signal loss due to impedance mismatch can be ignored. Standard impedances for coaxial cables are 50 ??, 75 ??, 93-125 ?? There is a compromise between maximum power transfer and minimum line loss. It is common to use transmission lines. Meanwhile, in the telephone industry or broadcasting industry, 75 ?? is used to minimize the line loss, and the impedance may be appropriately changed to the diameter of the central conductor 13 and the internal size of the connector to suit the purpose. If the impedance changes while the signal is propagating from the coaxial connector 10 to the microwave transmission line, a part of the incident wave is reflected to cause reflection loss and multiple reflections occur when there is more than one impedance change. Equivalent to the vector sum of the coefficients. Multiple reflections cause a resonance phenomenon.

The coaxial connector 10 is electrically connected to the transmission line of the microwave device via the center conductor 13.

In FIG. 3 the transmission line 18 is a micro strip line and the width is a function of the dielectric constant and thickness of the substrate used. In the connecting structure according to the present invention, the center conductor 13 and the structure of the coaxial connector 10 can be variously modified. Hereinafter, embodiments of the present invention will be described based on such a structure.

First embodiment

1 is a cross-sectional view of a bonded structure according to a first embodiment.

The coaxial connector of FIG. 1 includes a connector body 10, a dielectric 12, air 17, and a central conductor 13. Referring to Figure 1, the body 10 of the coaxial connector forms the overall appearance of the connector and includes a fastening means 11 for connection with a male connector (not shown), the outer conductor of the coaxial cable, i.e. a ground power source. Connected with The dielectric 12 accommodated inside the body 10 surrounds a part of the center conductor 13, and from the point where the inner diameter of the connector body changes, the inner material is air and the center conductor 13 according to the change of the inner diameter of the connector body. The diameter of) changes together with the diameter to maintain the impedance. The dielectric 12 is formed in a uniform size as a whole. The center conductor 13 includes a first terminal 14 electrically connected to the center conductor of the male connector and a second terminal 15 electrically connected to the transmission line. The first terminal 14 is grooved to improve electrical contact, thereby reducing electrical resistance of the contact portion and stabilizing the connection with the center conductor of the male connector. In the section between the first terminal 14 and the second terminal 15 filled with a dielectric, the central conductor 13 has a substantially uniform diameter. On the other hand, in the section filled with air, the size of the center conductor 13 gradually decreases, and at the same time, the inner diameter of the connector also decreases while maintaining a predetermined impedance.

In the first embodiment of the present invention, the end portion 15a of the second terminal 15 of the center conductor 13 is formed outside the terminal surface c of the connector body 10. In addition, the first embodiment of the present application includes an interval g for compensation of the impedance discontinuity according to the change of the diameter.

The variable that defines the characteristics of the signal propagation structure, such as a cable or connector, is called the characteristic impedance Z0. The characteristic impedance of a lossless cable is related to the inductance L per unit length and the capacitance C per unit length, which can be expressed by the following equation.

Z0 = ?? (L / C) [Ohm]

The characteristic impedance of the coaxial cable is represented by Equation 2 below.

Z0 = 138 / ???? Log10 (D / d) [Ohm]

Where D is the inner diameter of the outer conductor and d is the outer diameter of the center conductor.

If the impedance is the same between the two media through which the signal is transmitted, that is, if there is an impedance match, the maximum energy is delivered. Standard impedances for coaxial lines are 50 ??, 75 ?? and 93–125 ??, which is a compromise between maximum power transfer and minimum line loss. It is common to use transmission lines. In the telephone and broadcasting industries, 75 ?? is used to minimize line losses. Impedance can be increased by changing the diameter of the conductor or by adding voids to the dielectric.

If the impedance changes while the signal is propagating, a portion of the incident wave entering the secondary medium is reflected. The reflection coefficient is expressed by the following equation.

Reflection coefficient = ?? = V _i / V _R = (Z _R -Z _O ) / (Z _R + Z _O )

Here, V _i and Z _O are the incident voltage and the impedance of the first medium, and V _R and Z _R represent the impedance and the reflected voltage of the secondary medium.

Return loss is expressed by the following equation (4).

Return Loss [dB] = 10 Log ₁₀ [1- (1- ?? ² )]

When the connection structure according to the present invention is coupled to the PCB transmission line of Fig. 3, for example, as shown in the characteristic graph of Fig. 4, the return loss (S11) becomes -15 dB or less until the frequency becomes 27 Hz, so that the power transmission rate is lower. This can be seen that more than 95%.

Second embodiment

2 is a cross-sectional view of a connecting structure according to a second embodiment of the present application.

In the second embodiment, the same parts as in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

In the second embodiment, the diameter of the end 15a of the second terminal is changed. The changed second terminal 16 reduces the diameter of the end 15a of the second terminal to a size of 0.1 mm to 0.7 mm, and denotes a point at which a change in the diameter of the center conductor starts, a of the terminal surface of the end of the connector body. Given the position c and the distance between a and c as d, it is desirable to satisfy the following conditions. If this condition is not met, impedance matching may not be achieved and desired reflection characteristics may not be achieved.

d 0.5mm

The results measured by the applicant in order to empirically show the insertion and reflection characteristics of the present invention will be described with reference to FIG. 4.

FIG. 4 is a characteristic graph represented by the bonded structure when manufactured as shown in FIG. 3. FIG.

The transmission line used is a high frequency substrate with a dielectric constant of 3.38, a line width of 0.7 mm, a board thickness of 0.3 mm, and a total length of 10 mm. As shown in Figure 4, the return loss (S11) is very high power transmission rate of less than about -13dB insertion loss -1dB until the frequency is 27kHz.

The embodiments of the present invention have been described with reference to the drawings, which are not intended to limit the scope of the invention to the embodiments, and those skilled in the art can variously modify and modify the above embodiments without departing from the spirit and scope of the invention. Such modifications and variations are intended to be included herein as defined by the following claims.

According to the present invention, a coaxial connector having excellent high frequency characteristics is provided, which has a simple structure, an easy manufacturing process, a low production cost, and excellent insertion loss and reflection characteristics at an ultrahigh frequency of 10 Hz or more. It is also suitable for sending signals out via microstrip transmission lines within a microwave module package.

In addition, according to the present invention, the parasitic effect generated when connecting with the transmission line by self-compensation by the structural improvement of the pin in the connector to achieve impedance matching, by adjusting the interval d, compatibility and application of various types of connectors and microwave transmission line The castle is very high. Figure 4 is a result measured by connecting to the structure of Figure 3 using a connector manufactured by applying the technique of the present invention and Figure 5 shows the result measured using a conventional connector. As shown in the graphs when comparing Figs. 4 and 5, the difference in insertion and reflection loss from the conventional connector can be clearly seen from about 10 GHz. In the case of FIG. 4, the return loss up to 27 GHz shows an excellent characteristic of -13 dB or less, while in FIG. 5, -13 dB is shown at 12 GHz.

Claims (7)

A center conductor having a first terminal and a second terminal, a body portion disposed concentrically on the outside of the center conductor to form a housing, and provided between the center conductor and the body portion to electrically separate the two conductors. In the connection structure for high frequency signal transmission including a medium, The diameter of the first terminal of the center conductor is larger than the diameter of the second terminal, A portion of the medium is a dielectric, the other corresponds to air, And the inner diameter of the body portion and the diameter of the central conductor have a structure in which the medium is changed in a range corresponding to air. The connecting structure according to claim 1, wherein the length of the section filled with the dielectric is T, and the length of the section filled with air is S, wherein the condition S ?? 0.8T is satisfied. The connection structure according to claim 1, wherein the inner diameter of the center conductor is reduced at the portion where air starts to fill between the body portion and the center conductor, but the diameter of the center conductor is kept constant. The connection structure according to claim 4, wherein the diameter of the center conductor is reduced as the inner diameter of the body portion is reduced within a range in which air is filled between the body portion and the center conductor. The connecting structure according to claim 1, wherein the inner diameter of the body portion provided on the end side of the second terminal of the center conductor is kept constant, and the end side diameter of the second terminal of the center conductor is reduced. 7. The method according to claim 6, wherein a is a point where the end diameter of the second terminal of the center conductor is reduced, and c is a position of the terminal face of the body located at the second terminal side of the center conductor. A connection structure wherein d, which is an interval of c, satisfies a condition of d ?? 0.5 mm. The connector structure according to any one of claims 1 to 6, wherein the connection structure is an SMA connector, an N series connector, a TNC connector, a BNC connector, an F series connector, a G series connector, a DIN connector, an OSMP connector, an SMB connector, and an MCX connector. , SSMT connectors, OSMT connectors, MMXC connectors, right angled connectors in 0.141, 0.250, 0.0856, 0.141, RG316, RG188, 1/2 '', 7/8 '' sizes, semi rigid A) coaxial connector, characterized in that either coaxial cable or semi flexible coaxial cable.