JPH03113920A - Antenna matching device - Google Patents

Abstract

PURPOSE:To attain high speed matching by connecting plural reactance elements in using as variable reactance elements in series or in parallel via a switch or the like, and varying the combination of ON, OFF of the switches so as to vary a combined reactance. CONSTITUTION:Matching information at a prescribed frequency such as transmission frequency is stored in a memory memo and a control circuit CONT controls a matching circuit TUNE based on the information. When the matching is taken again because of the start of transmission or change of the transmission frequency, for example, a relay control voltage is turned on/off to take an optimum capacitance based on the optimum matching information in said transmission frequency. Or the matching is taken by changing the voltage applied to a switching element to switch the combination of switches momentarily. Thus, since the time requiring to take matching is enough to be a time switching a switch such as a relay, the high speed matching in comparison with a conventional antenna matching device is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an antenna matching device used for frequency hopping or optimal frequency control, and particularly to one that performs matching at high speed.

(Prior art) If the impedance of the antenna system of radio equipment is not matched, the power supplied from the transmitter will not only be reflected without being radiated from the antenna, resulting in poor power efficiency, but will also return to the transmitter and be transmitted. There is a risk of destroying the machine. Furthermore, when multiple antenna systems are used, a portion of the reflected power is distributed to other antenna systems in addition to the transmitter, and there is a risk of damaging these systems or damaging the antenna switch.

In order to avoid these problems, it is necessary to match the power amplifier output impedance of the transmitter and the radiation impedance of the antenna, and antenna systems of radio equipment have conventionally been equipped with antenna matching devices.

FIG. 4 is a circuit diagram showing an example of a conventional antenna matching device using a low-pass filter type matching circuit.

In the figure, L is a variable inductive element, and C is a variable capacitance element. By adjusting the values of these variable reactance elements, the radiation impedance of the antenna ANT and the transmitter TX can be adjusted.
This is to match the output impedance of the two or the cable that connects the two. The specific values of these elements vary depending on the type of antenna or frequency used, but for example, when covering the entire shortwave band with one whip antenna, the impedance of the antenna changes depending on the frequency to be transmitted, so The value will be consistent.

However, conventional antenna matching devices have the following drawbacks.

That is, in a variable capacitor, which is a common variable capacitance element, as shown in FIG. 5, one of two opposing electrode plates is fixed, and the other is rotated by a shaft to change the area where the picture electrode plates intersect. The capacity can be changed by doing this. Therefore, in order to set the capacitance of the variable capacitor to the required value, the shaft must be rotated by the required angle, but since the drive method is manual or mechanical using a motor, it takes several seconds or more to set the capacitance value. It takes several minutes.

It couldn't be done instantly.

However, antenna matching devices used in spread spectrum communications, which have been developed in recent years, especially frequency hopping methods or optimal frequency control, must perform matching at high speed by following rapidly changing frequencies. Using a variable capacitor would not be able to follow the frequency changes.

Furthermore, conventional variable capacitors change their capacitance continuously, and are not suitable for changing the capacitance using digital signals using a computer or the like.

(Object of the Invention) The present invention was made in order to eliminate the drawbacks of the conventional antenna matching device as described above, and an object of the present invention is to provide an antenna matching device that enables high-speed matching. shall be.

<Summary of the Invention> In order to achieve the above object, the present invention is configured as follows.

That is, in an antenna matching device, a plurality of reactance elements are connected in series or in parallel as variable reactance elements via switches, etc., and the combined reactance value is changed by changing the combination of ON and OFF of the switches. Make the characteristics of the vessel variable.

(Example) The present invention will be described in detail below based on the illustrated example.

FIG. 1 is an antenna system diagram showing one embodiment of the present invention, and is an example of automatic matching.

In the figure, radio waves sent from the transmitter TX are sent from the air 11ANT via a matching circuit TUNE. or,
Matching information at a required frequency such as a transmission frequency is stored in the memory tnemo, and the control circuit C0NT controls the matching circuit TUNE based on this information.

The antenna matching device according to the present invention operates as follows.

When resetting the matching due to starting transmission or changing the transmission frequency, the relay control nt pressure is set to 0N- to obtain the optimal capacitance value based on the optimal matching information for the transmission frequency stored in advance in the memory memO. OF
By changing the voltage applied to the FL or switching element, the combination of switches is instantaneously switched to achieve matching.

FIG. 2 shows details of the tuning variable capacitor used in the matching circuit. That is, by using a required number of capacitors CL, C2, .
The combined capacity changes without rotating the shaft as in the conventional case. A relay may simply be used as the switch, but alternatively, switching elements such as PIN diodes may be provided, and control voltages applied to each of them may be changed, or the combination of elements to be switched may be changed. Regardless of whether a relay or a switching element is used, the time required for matching is extremely short compared to when a conventional variable capacitor is used.

For example, when a high-power relay such as a vacuum relay is used, it takes several milliseconds, and when a high-speed switching element is used, it takes only several microseconds.

As explained above, the antenna matching device according to the present invention requires only the time required to switch switches such as relays to achieve matching, so matching can be achieved extremely quickly compared to conventional antenna matching devices, and in a short time. It can also be used in a frequency hopping method in which the frequency changes dramatically.

Moreover, since it is only necessary to turn on and off a switch, control using digital signals can be easily performed.

By the way, when a relay is used as a switch, how to obtain isolation becomes a problem. Especially in high frequency circuits, as the number of relays connected in parallel increases, isolation decreases due to stray capacitance between relay terminals.
If it is difficult to increase the capacity by connecting a large number of variable capacitors in parallel, the following modification can be used in this case.

FIG. 3 shows a modified embodiment. That is, at least one circuit of the switch connected to the capacitive element is a two-contact relay, and the common terminal of the relay is connected to the capacitive element, the make contact is connected to the signal line, and the break contact is grounded.

With this configuration, when the relay is in the oven, the contact plate is connected to the break contact, and the capacitive element connected to the common terminal is grounded. Therefore, even if a high frequency wave passes from the make contact to the break contact, since the break contact is grounded, it will not pass through the capacitive element and be output to the output terminal, but will fall to the ground. Therefore, the number of relays connected in parallel can be increased without deteriorating the isolation, and the variable range of the variable capacitor, that is, the frequency range that can be matched can be expanded.

Although the above embodiments have been described with respect to the case where the capacitance is changed, it is also possible to apply the present invention to an inductive element.

Further, the switch switching method and relay connection method according to the present invention can be widely applied not only to antenna matching devices but also to filter groups or other similar cases where a large number of reactance values are selectively connected. In particular, when applied to a high-power, high-frequency interference removal filter, a desired filter can be instantly selected from a large number of filters, which is effective in dealing with sudden interference waves.

(Effects of the Invention) Since the antenna matching device according to the present invention is configured and operates as described above, it has a remarkable effect on matching the antenna system at high speed, and the frequency jumps in a short period of time. It can also be used for changing frequency hopping methods. In addition, since many relays can be connected in parallel without compromising isolation, a variable capacitor with a large capacity can be realized, which has a significant effect in expanding the frequency range that can be matched.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an antenna matching device according to the present invention, FIG. 2 is a circuit diagram showing a variable capacitor 1 cable according to the present invention, FIG. 3 is a diagram showing a modified embodiment, and FIG. FIG. 4 is a circuit diagram showing a conventional antenna matching device, and FIG. 5 is a diagram showing a conventional variable capacitor.

Claims (3)

[Claims] (1) In an antenna matching device used in the antenna system of radio equipment, a plurality of reactance elements are connected in series or in parallel via switches etc. as variable reactance elements, and the combined reactance is achieved by changing the ON/OFF combination of the switches. An antenna matching device characterized in that the characteristics of the matching device are made variable by changing the value. (2) A patent claim characterized in that at least one circuit of the switch connected to the reactance element is a two-contact relay, the common terminal of the relay is connected to the reactance element, the make contact is connected to the signal line, and the break contact is grounded. Antenna matching device according to item 1. (3) Store in advance the combination of the switches to obtain the reactance value that provides the optimum matching state at the desired frequency, and when the frequency is switched, the switches are automatically set to obtain the optimum reactance value for the frequency. Claim 1 or 2 characterized in that
Antenna matching device as described in section.