JPS62190711A - High frequency magnetic field generator/detector - Google Patents

Abstract

PURPOSE:To improve the stability and the efficiency of a high frequency magnetic field generator/detector used in a unclear magnetic resonance apparatus by supplying power in balance to the nonprojections of split conductor plates by a balanced impedance matching circuit and a balance/imbalance converter. CONSTITUTION:Split conductor plates, e.g., vertical bands 1a become electrodes 7a, 7b, and a first variable capacitor 8a is connected between the electrodes 7a and 7b. A balance/imbalance converter 9 is, for example, a coaxial cable having an electricity of 1/2 wavelength. The resonance frequency of a stereoscopic circuit which operates as an equivalent series resonator and an impedance matching frequency are adjusted by a first variable capacitor 8a. Second and third variable capacitors 8b, 8c are disposed in a balance type, and, when a coaxial cable having an imbalanced impedance and a transceiver are coupled with a terminal 6, the maximum power is supplied to a load by using the converter 9, and since voltages of equal amplitude and reverse polarities are applied to the electrodes 7a, 7b, and an LC series resonator is completely supplied with power in balance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high frequency magnetic field generator/detector, particularly to a high frequency magnetic field generator/detector used in a nuclear magnetic resonance apparatus.

[Conventional technology]

The evening map is, for example, [Journal of Magnetics]
Resonance (Journal of Magnetic
This is a perspective view showing a conventional high-frequency magnetic field generator/detector shown in Resonance) J, Vol. When a pair of conductor plates, such as a copper plate, are arranged in a cylindrical shape, they are bent by coils arranged symmetrically with respect to a predetermined axis (not shown) K, resulting in a vertical band (
vertica: non-protruding part (L band)
la) and protrusions called wings (
tb). (2) is the adjacent wing (lb
) with a fixed capacitor inserted between them. (3) is a pair of conductor rings for electric field shielding arranged inside the wing (lb) via an insulating layer (not shown) and with the above-mentioned axis as a common center; one conductor ring (3a ) is called the top guard ring and the other conductor ring (3b
) is called the bottom guard ring. (4(a)
, (#b) are electrodes formed integrally with the conductor plate O) and the conductor ring (3), respectively. (Ria).

(b) is a matching variable capacitor connected in series between these electrodes r+a) and nb). (6) is the transmitter/receiver (
This terminal is connected to the electrode (lIa) via the variable capacitor (ria) and is connected to the electrode (lIa) via the variable capacitor (lia).
ib).

A conventional high-frequency magnetic field generator/detector is configured as described above, and includes a conductor plate (1), a fixed capacitor (2), and a conductor ring (3).
) forms a three-dimensional circuit that equivalently functions as an LC series resonant circuit. Furthermore, since the electrodes (<za) and (lIb) are capacitively coupled, the variable capacitors (ta) and (tb
) can be used to adjust the resonant frequency. Therefore, by matching the diimpedance with a variable capacitor (rag, (rib)), a transmitter/receiver having a predetermined impedance can be connected to the terminal (6).The conductor ring (3) is used as an electric field shield as described above. Therefore, it is used to reduce dielectric loss within the measurement object due to the generated electric field when the measurement object is installed in a high-frequency magnetic field generator/detector.

[Problem that the invention seeks to solve]

Conventional high-frequency magnetic field generators and detectors do not take into account the balance-unbalance conversion of circuit impedance, so if a common-mode current flows through the coaxial cable connected to the terminal and the operation becomes unstable, the efficiency will decrease. There was a problem.

This invention was made to solve these problems, and takes into account the balance and unbalance of circuit impedance.
The aim is to obtain a stable and efficient high-frequency magnetic field generator/detector.

[Means for solving problems]

The protruding part is cut into two parts, and a seventh variable capacitor is connected between the divided non-protruding parts, and a second variable capacitor and a third variable capacitor are respectively connected to each end of the first variable capacitor. This system includes a balanced impedance matching circuit and a balanced-unbalanced converter connected to the balanced impedance matching circuit.

[Effect]

This departure F! In A, the balanced impedance matching circuit and the balanced unbalanced converter supply balanced power to the bisected non-protruding portion.

〔Example〕

FIG. 1 is a perspective view showing an embodiment of the present invention. As in the conventional example, there is a pair of conductors (1), whose protrusions or wings (tb) are brought close to each other, and then these A three-dimensional circuit is constructed by electrically connecting the wings (tb), that is, in this embodiment, by capacitively coupling them with a fixed capacitor (2) as in the conventional example. However, unlike the conventional example,
In this invention, among l pairs of conductor plates (1)! For example, in the conductor plate on the right side in FIG.
)become. (ga) is the first variable capacitor for the LC series resonant circuit and impedance matching, and the electrode (?a
), r7b). (tb) and (gc) are respectively connected to each end of the first variable capacitor (ta),
Together with the first variable capacitor (ta), a balanced impedance matching circuit (1) is constructed. (9) is the λ-th variable capacitor (t) of this balanced impedance matching circuit (1).
b) and a balanced-unbalanced converter connected to a third variable capacitor (gc), for example a coaxial cable with an electrical length of 1 wavelength of the section. In addition, vertical band (ta)
The angle θ formed by this is 0°〈θ〈900.

In this invention, the first variable capacitor (ta) adjusts the resonant frequency and impedance matching frequency of the three-dimensional circuit that functions as an isometric series resonant circuit. In addition, by arranging the λ-th variable capacitor (tb) and the third variable capacitor (tc) in a balanced manner and using a balanced-unbalanced converter (9), the coaxial cable with unbalanced impedance and the transmitting/receiving Connect the device to the terminal (6)
When coupled to , the maximum power can be delivered to the load and the maximum power sensed. In this case, voltages of equal magnitude and opposite polarity are applied to the electrodes (7a) and (rib), so that the LC series resonant circuit is completely balanced.

This is the reason why the stability and efficiency of the high-frequency magnetic field generator/detector can be increased. Although not shown, by installing an electromagnetic shielding conductor tube, that is, a metal cylinder having a common central axis, outside the high-frequency magnetic field generator/detector of the present invention, the loss of the LC resonant circuit is reduced, and the generated The spatial uniformity of the high-frequency magnetic field is improved.

FIG. 2 is a perspective view showing a modification of the embodiment shown in FIG.
) is used.

FIG. 3 is a perspective view showing another embodiment of the present invention, which differs from the embodiment shown in FIG. 1 in the way the protrusion or wing (lb) is electrically connected, and is a fixed capacitor (2). A wing (tb
) are electrically connected.

Although not shown in FIG. 1, the wings (tb) may be electrically connected using conductive wires or conductors instead of capacitively coupling with the fixed capacitors (, 2).

The second figure is a perspective view showing a modification of the embodiment shown in FIG. 3, and is similar to that in FIG. 2.

[Effects of the Invention] A balanced structure consisting of a first variable capacitor connected between the non-protruding parts, a first variable capacitor connected to each end of the first variable capacitor, and a third variable capacitor connected to each end of the first variable capacitor. Since the balanced type impedance matching circuit and the balanced/unbalanced converter connected to the balanced type impedance matching circuit are provided, it is possible to obtain a highly stable and efficient high frequency magnetic field generator/detector.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of this invention, FIG. 2 is a perspective view showing a modification of the embodiment shown in FIG. 1, and FIG. 3 is a perspective view showing another embodiment of this invention. , Fig. 3 is a perspective view showing a modification of the embodiment shown in Fig. 3, and Fig. 1 is a perspective view showing a conventional high frequency magnetic field generator/detector. (1) is a conductor plate, (/a) is a vertical band, (t
b) is a wing, (2) is a fixed capacitor, (ra) is a first variable capacitor, (llb) is a third variable capacitor, (tc) is a third variable capacitor, (1) is a balanced impedance matching circuit, ( Te) is a balanced-unbalanced converter. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. 1; Conductor plate 1Q, Verteurbacid 1b ° Win r 2. National history piece 5 tier 2"W. 3, Conductor ring 8" Balanced type Ni C'-ta" varnish hardening lable b8o.
Fang 1 Kagofu〉Te゛'-sa 8b: 2nd Kagoshidden Nisa 8C: Fang 37T t: l city 9, 1,000 f#! TI 1000 iFrg: 2nd figure procedural amendment (voluntary) 1. Display of the case Patent Application No. 51969 of 1985 2, Name of the invention High frequency magnetic field generator/detector 3, Person making the amendment Representative Moriya Shiki 4, Agent 6, Contents of the amendment (1) Page 6 of the specification The description of “conductor (1)” in line 13 is corrected to “conductor plate (1)”. (2) Insert "[70°<θ<100', preferably"] after the statement "Angle θ is" on page 7, line 13 of the specification. (3) Insert "two" after the statement "and" on page 8, line 15 of the specification. (4) Insert the following statement between lines 6 and 7 on page 4 of the specification. "Although Figures 3 and 4 show the case where there is a conductor ring (3), the conductor ring (3) may not be provided. Also, in the configurations of Figures 2 and 4, the power supply is When performing from a point, a balanced impedance matching circuit (8
), the balance/unbalance converter (9) may be used as one set, and the other may be terminated with a variable capacitor for adjustment. ”

Claims (7)

[Claims] (1) At least one pair of H-shaped conductor plates is arranged symmetrically with respect to a predetermined axis, the protrusions of the conductor plates are brought close to each other, and then these protrusions are electrically connected. The constructed three-dimensional circuit and the at least one pair of conductive plates are divided into two by cutting the non-protruding part of one of the conductive plates of each pair, and a first A balanced impedance matching circuit comprising a variable capacitor, a second variable capacitor and a third variable capacitor connected to each end of the first variable capacitor, and a balanced unbalanced converter connected to the balanced impedance matching circuit. Equipped with
A high frequency magnetic field generator/detector, characterized in that the three-dimensional circuit and the first variable capacitor equivalently constitute an LC series resonant circuit. (2) The three-dimensional circuit includes a pair of conductor rings installed inside the protruding portion of the conductor plate with an insulating layer interposed therebetween and having a predetermined axis as a common center. High-frequency magnetic field generator/detector described in Section 1. (3) The high-frequency magnetic field generator/detector according to claim 1 or 2, wherein the three-dimensional circuit has a conductor tube having a predetermined axis as its central axis on the outside of the conductor plate. (4) High-frequency magnetic field generation and detection according to any one of claims 1 to 3, wherein the balanced-unbalanced converter is a coaxial cable having an electrical length of 1/2 wavelength. vessel. (5) The high frequency magnetic field generator/detector according to any one of claims 1 to 4, wherein the electrical connection of the protrusion is capacitive coupling using a fixed capacitor. (6) The high frequency magnetic field generator/detector according to any one of claims 1 to 4, wherein the electrical connection of the protrusion is by pressure contact or soldering. (7) The high-frequency magnetic field generator/detector according to any one of claims 1 to 4, wherein the electrical connection of the protrusion is by a conducting wire or a conductor.