JPH02208572A - High frequency probe - Google Patents

Abstract

PURPOSE:To make it possible to measure a place having a small occupying area readily by constituting a probe with a tapered flexible central conductor and a pair of tapered plate-spring type outer conductors which surround said central conductor. CONSTITUTION:In a central conductor 1, a tip part 1a is thin and the thickness becomes larger toward the root of the conductor. A tapered shape is provided from a tip part 2a toward a root in a plate spring type outer conductor 2. The central conductor 1 and the outer conductors 2 are assembled into a supporting part 3 which is formed as a unitary body together with a connector. The conductor 1 is made to penetrate through a cylindrical insulator 4 and connected to a central-conductor coupling part 5 of the connector. Both conductors 1 and 2 are flexible and generate contact pressures suitable for testing electrodes. Therefore high frequency measurement in a microstrip structure can be performed readily. Furthermore, the measuring circuit can be made compact, and the cost of the apparatus can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high frequency probe for externally monitoring signals propagating in a microstrip line transmission path in a high frequency band higher than a microwave band.

[Conventional technology]

Conventionally, when attempting to monitor high-frequency signals in the microwave band or above, a commonly used method was to insert a directional coupler at the point on the transmission line where the signal was to be monitored and extract the signal. According to this method, it is possible to reliably extract a signal of a certain magnitude, but the use of a directional coupler requires a large space and is costly.

[Problem to be solved by the invention]

In recent years, microwave circuits have often been formed with a microstrip structure, and waveguides have been used only in a limited number of areas. A directional coupler using this microstrip circuit requires a length of at least ^/4 (λ is the wavelength), so it has the drawback of occupying a large circuit area. Furthermore, it is necessary to use a connector to connect the signal extracted by the directional coupler to an external measuring device or circuit, and in addition, the connector is usually equipped with a non-reflection terminator (generally due to the characteristic impedance of the line, etc.). (with a connector with a new resistor installed inside). Another problem was that microwave connectors and terminators were very expensive.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate these drawbacks and provide a high-frequency probe that uses a flexible predetermined characteristic impedance circuit, can measure a narrow place with a small footprint, and can be constructed at low cost.

[Means to solve the problem]

The high-frequency probe of the present invention has a tapered flexible central conductor with a thin tip and a thick base, and a pair of tapered and leaf spring-shaped outer conductors disposed diagonally on both sides of the central conductor. The present invention is characterized by comprising a support member that supports the center conductor and the outer conductor at their base portions, and a connector portion that is formed integrally with the support member and is connected to an external cable.

〔Example〕

FIGS. 1(a), 1(b), and 1(c) are a front view, a side view, and a vertical cross-sectional view of one embodiment of the present invention, and the cross-sectional views show a cross section including the center of the signal propagation axis. In FIG. 1(c), the center conductor 1 has a thin tip portion 1a and tapers toward the root. Outer conductors 2 are arranged in the form of a flat plate on both sides of the central conductor 1, and similarly taper from the tip 2a to the base. The support portion 3 of the probe that supports the outer conductor 2 also serves as a portion for gripping the high-frequency probe with the hand. The outer conductor 6 of the connector, which is integrally formed with the support portion 3, is threaded in this embodiment and serves as a connecting portion of the connector. A coupling portion 5 of the center conductor of this connector is connected to the center conductor 1.

Here, a description will be given of how the center conductor 1 and the outer conductor 2 are supported and maintain their positional relationship. In FIG. 1(b), the support member 3 is provided with a slot 3a, into which the flexible leaf spring-shaped outer conductor 2 is inserted, and the tip of the support member 3 is fixed with a tapered screw (not shown). By tightening, the outer conductor 2 is firmly attached to the support member 3.

Next, the center conductor 1 is inserted into a cylindrical insulator 4, and this insulator 4 is further inserted into a hole bored in the support member 3 to be supported.

In FIG. 1 (a) seen from the tip of this high-frequency probe, a support member 3 is arranged concentrically with respect to the center conductor 1, and a leaf spring-shaped outer conductor 2 is further sandwiched between the support member 3.

Figures 2 (a), (b), and (c) are A-A in Figure 1 (C).
, B-B, and CC cross-sections. Cross-section A-A is the part supporting the center conductor 1, cross-section B-B is the middle part, and cross-section CC is the part near the tip.

Figures 3(a) and 3(b) are distribution diagrams of electric lines of force due to the line structure of the high-frequency probe. Figure 3(a) shows the part near the tip, and Figure 3(b) shows the middle part. There is. This electromagnetic field distribution is concentrated in the gap between the center conductor and the outer conductors 2 on both sides thereof. At the support of the probe, the electromagnetic field distribution is coaxial.

The electromagnetic field changes smoothly from the tip to the base and then to the connector.

FIG. 4(a) is a plan view of the microstrip structure used in this embodiment, and it is assumed that a signal on this signal transmission path is to be monitored. Center conductor 11 on substrate 10
An electrode 13 is provided branching from the center conductor 11 through a high resistance portion 12, and ground vias 14 are provided on both sides of the electrode 13. In this state, the signal propagating through the center conductor 11 is
2 has a high resistance, so it is hardly affected.

Next, when monitoring this signal, the high frequency probe of this embodiment is brought into contact with the electrode 13 and the ground hole 14, as shown in FIG. 4(b). Tip part 1 of probe center conductor 1
a to the electrode 13, and the tip 2a of the probe outer conductor 2 to the ground hole 14. In this case, both the center conductor 1 and the outer conductor 2 of the probe are flexible and are slightly deflected and deformed independently, thereby generating contact pressure corresponding to the deformation.

This achieves a comfortable contact between the center conductor 1 and the outer conductor 2, and the negative portion of the signal present in the microstrip line is taken out to the high frequency probe via the high resistance section 12.

FIG. 5 is an equivalent circuit diagram when the high frequency probe of this embodiment is used. Let the resistance value of the high resistance part 12 be Rh,
Characteristic impedance Z of the line. If Rb>Za is selected, the influence of the high frequency probe on the main line can be almost ignored.

〔Effect of the invention〕

As explained above, the high frequency probe of the present invention maintains the same characteristic impedance from the tip to the connector, and discontinuities as a signal propagation line are extremely small.The tip bends smoothly with the center conductor and outer conductor. , high frequency measurements in microstrip structures can also be easily carried out.

According to the high-frequency probe of the present invention, it is not necessary to incorporate a directional coupler having a large area into the circuit, and the measurement circuit can be made smaller. It also has a great effect of lowering the price of the equipment as it does not require any additional equipment.

[Brief explanation of the drawing]

FIGS. 1(a), (b), and (c) are a front view, a side view, and a vertical sectional view of a high-frequency probe according to an embodiment of the present invention, and FIGS. 2(a), (b), and (c) are A-A, B-B, C in Figure 1
-C cross-sectional views, FIGS. 3(a) and (b) are electric field distribution diagrams of the line of the high-frequency probe of this embodiment, and FIGS. 4(a) and (b).
) is a plan view of a microstrip line and a perspective view when monitoring the microstrip line for explaining how to use the high frequency probe of this embodiment, and FIG. 5 is an equivalent circuit diagram including the high frequency probe of this embodiment. 1... Center conductor, 1a... Center conductor tip, 2...
- Outer conductor, 2a... Outer conductor tip, 3... Support member, 4... Cylindrical insulator, 5... Connector center conductor coupling portion, 6... Outer conductor coupling screw, 10. ... Substrate (board), 11... Center conductor, 12... High resistance part, 13... Electrode, 14... Ground hole.

Claims (1)

[Claims] A tapered flexible center conductor with a thin tip and a thick base, a pair of tapered and leaf spring-shaped outer conductors arranged diagonally on both sides with this center conductor in between, and these center conductors and outer conductors. 1. A high-frequency probe comprising: a support member that supports the base member at each base; and a connector portion that is formed integrally with the support member and is connected to an external cable.