JPS58100505A - Variable tuning type antenna device - Google Patents

Abstract

PURPOSE:To extend the function operating frequency area width, by outputting an antenna output using a shortened antenna element via a high or a low-pass filter selectively. CONSTITUTION:A variable tuning circuit 4 is connected to a power feeding terminal of shortened radiation elements 1a, 1b, and the output passes through a high-pass filter 10 and a low-pass filter 8 where the crossover frequency is set to the boundary frequency of the 1st and 2nd antenna tuning frequency is set, switchingly with selection meansI, II, allowing to cover a broad band with a single antenna element. It is preferable for the elements 1a, 1b to be zigzag shaped folded conductors or helical conductors.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable tunable antenna device using a shortened antenna element, and its purpose is to expand the functional operating frequency range.

When a resonant variable reactance circuit consisting of a resonant element and an inductive element is used as the tuning circuit section of a shortened antenna device,
The inductive and capacitive reactances present in its resonant characteristics function to cancel the inherent reactance characteristics of the shortened antenna element itself. In commonly designed shortened antenna arrangements, a tuned channel is added that exhibits an inductive reactance relative to the capacitive reactance of the shortened antenna element. In the case of B, there is necessarily a simple tuning frequency band in the obtuse frequency band in addition to the 118 digits of the required 0ill.

In this case, the following points can be mentioned as intermediate points.

■When mainly using the first tuning frequency band.

The existence of the tuning frequency band II2 is not only unnecessary, but also causes a significant deterioration in the receiving performance of the receiver due to the reception of interfering radio waves by the second tuning frequency band ilIm. Furthermore, in the case of a transmitting antenna, it causes an increase in the amount of spurious interference radio waves radiated.

This is because there is a limit to the variable reactance range of the variable reactance element used in the zero-tuned resonant circuit.

The bandwidth of the required tuning frequency band of flXl is narrow.

Therefore, the present invention provides an antenna section including a shortened radiation element and a variable tuning circuit section connected to its feeding side terminal, and a boundary between a first antenna tuning frequency of the shortened radiation element and an antenna nll1 station wave number. A band selection unit has a high-pass filter and a low-pass filter whose respective crossover frequencies are set to the domain frequencies, and the high-pass filter and low-pass filter of this band selection unit are selected to connect the power supply terminal A band cutter is provided between the antenna parts to cover a wide band with a single antenna element.Embodiments of the present invention will be explained below with reference to Figs. 111 to 85.

FIG. 1 shows the configuration of a variable rAa type antenna device in a receiving device.

To the supply *a terminal of the shortened radiant element (1m) (lb),
A variable tuning circuit section (6) consisting of a parallel circuit of a variable capacitance element (2) and an inductor (3) is connected. The neutral point (1m of the inductor) is grounded, and the variable circuit section (
The impedance adjustment capacitor (2) is connected to the parallel resonance terminal (4a) of 4), and the common switch terminal (6)
The impedance of the line matches the impedance of the power supply line.

When the common switch terminal (6) is connected to the switch terminal (6a), the common switch terminal (7) is also connected to the switch terminal (6a).
Child(?a)icI! Continued. This switching state is lit
The switching state is as follows. Further, the common switch terminal (6) sets the switching state to the switching state of Ill2.

In the switching state of Ill, the low-pass filter CI
) is connected to the supply terminal (9), and in the second switching state the high-pass filter (2) is supplied! ! ! Terminal (s+)
connected to.

The ms diagram shows the actance characteristics and gain characteristics of the antenna section consisting of the shortened radiating element (1 m) (1 m) and the variable tuning circuit section (4).

In IN8 diagram, shortened radiating element (1m) (
its dog reactance characteristic, and the 9 actance characteristic of the variable 11iP1 circuit section (4) is XTLe.
It is set to X+c. In the case of Jin, ・The frequency f1 is the same as the required Ill antenna, i + ui wave number, and 1 frequency rg is found! The 0 frequency f, which is the antenna tuning frequency of , is the parallel resonance frequency of the variable tuning circuit section (-).

Radiating element (1aXlbX) reactance characteristics XM
and variable tuning circuit section (4) glue actance characteristics xyz t
The XTCO composite reactance is shown in Figure IIz, and
M1 ToX M.

is the reactance component of the antenna. The frequency f1 at which the 9 actance becomes zero is the required first antenna tuning frequency, and the frequency f is the second antenna tuning frequency.

The gain characteristic at the common switch terminal (6) in the case of CC+ is %II! As shown in Fig. 2), for antenna characteristics of 6 or more with peaks at frequencies f and fl, there is a low-pass filter with characteristics as shown in LPF in tIMs diagram (a), and a low-pass filter as shown in HPF. Install a high-pass filter with suitable characteristics. And switch I and switch L
By switching settings, the low-pass filter (8) or the high-pass filter (8) is selectively connected depending on the desired antenna co-station wave number band.

When the low-pass filter (8) containing the frequency f1 is selectively connected, the gain characteristic at the feed terminal (9) becomes #I
There is a peak at frequency f1 as shown in Hataku &), and the peak at frequency f is suppressed.

When a high-pass filter including the opposite c and Ml wave number f is selectively connected, the gain characteristic at the feed terminal (9) has a peak at the frequency fl as shown in the figure, and a peak at the frequency f15). is suppressed.

It goes without saying that the selected princess 1 or l! The peak t of the wave number of the IA leg of the antenna in question is expressed by the storage element (
Variable control is possible by changing the capacitance of 2).

In addition, in the above embodiment, the shortened radiant element (1g)
Although a straight metal rod with a rectangular cross section was used as (lb), it may also have a square or circular cross section.

Even if it is not a straight line, it can be folded in a zigzag shape as shown in Figure 4.
A distributed constant inductance element (t
xa) (ob).

Similarly, a distributed constant inductance element (l1m) with a helical winding shape as shown in FIG.
) can also be configured.

The above embodiment was explained using the case of a receiving device as an example, but
It can also be used for transmitting devices.

The amount of spurious interference radio waves radiated can be reduced.

As explained above, according to the variable 81i type antenna device of the present invention, conventionally, it is not possible to expand the narrow range of variable tuning control frequency band near the antenna tuning frequency f of 1111 to near the second antenna tuning frequency f3. A single antenna element can cover a wide band. In addition, it is possible to suppress unnecessary antenna tuning gain peaks other than the earthen antenna tuning gain peak, which can improve reception performance in the case of a receiving device, and suppress the radiation of spurious interference radio waves in the case of a transmitting device. The amount can be reduced.

[Brief explanation of the drawing]

The lit diagram is a wl diagram of an embodiment of the variable tunable antenna device of the present invention, Figure 61 is a diagram of the actance characteristics and gain characteristics of the antenna section, and Figure 8 is the wave number characteristics around the main IA of Figure 61 and each switching wave. State-specific frequency characteristic diagram, 4th
Figures 1 and 116 are illustrations of other embodiments of the shortened radiating element. (lb) - shortened radiating element, (4)...
Variable tuning circuit section, (h) - Impedance adjustment capacitor, (1) - Low pass filter, (9) - Power supply terminal, 0Q - High pass filter, (1) (1) - Switch No. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] L: An antenna section including a shortened radiating element and a variable tuning circuit section connected to its feeding side terminal, and a boundary between the first antenna tuning frequency of the shortened radiating element and the antenna tuning frequency of II2. a band selection unit having a high-pass filter and a low-pass filter in which respective coosover station wave numbers are set in the domain frequencies; A variable tuning type antenna device comprising: a band switching setting section which selects a high pass filter and a low pass filter of the band selection section and is interposed between a power feeding terminal and the antenna section. 1. The tunable antenna device according to claim 1, wherein the shortened radiation element is a distributed constant inductance element made of a zigzag-shaped folded conductor. 3. The tunable antenna device according to claim 1, wherein a distributed constant inductance element made of a helical conductor is used as the shortened radiation element.