JPH0522011A - Portable radio equipment - Google Patents

Abstract

PURPOSE:To always obtain a satisfactory radiating characteristic by contacting one feeding terminal to the current antinode of an antenna element when two feeding terminals are provided and the antenna element is housed in the enclosure of the radio equipment. CONSTITUTION:Feeding terminals 5 and 6 are arranged so as to execute feeding from the current node of an antenna terminal part when pulling out an antenna element 1 from an enclosure 8 and to execute feeding from the current antinode of the antenna element 1 in the case of housing the antenna element 1 in the enclosure 8 on the other hand, and these feeding terminals 5 and 6 are slid and contacted with an antenna. Namely, when the antenna is pulled out, feeding is executed from the lower terminal through a matching circuit a3 by the feeding terminal A5 and in this case, the feeding terminal B6 is not contacted with the antenna element 1 at all. On the other hand, when the antenna is housed, the feeding terminal B6 is contacted with a point corresponding to the electric length of an almost 1/4 wavelength from the upper terminal of the antenna, and feeding is executed from the feeding point 6 and operated similarly to the case of providing the two antennas of upper and lower 1/4 wavelength whip antennas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a portable wireless device having a retractable whip antenna, and more particularly to a portable wireless device capable of obtaining a high antenna gain even when the whip antenna is accommodated.

[0002]

2. Description of the Related Art FIGS. 10 and 11 show an example of a portable radio device having a conventional retractable whip antenna. Of these figures, FIG. 10 shows the case of a linear whip antenna,
FIG. 11 shows the case of a coil-loaded whip antenna. In each case, (a) shows the state when the antenna is pulled out, and (b) shows the state when the antenna is housed.

In FIG. 10, 21 is a linear whip antenna element, 23 is a matching circuit, 24 is a 50Ω coaxial line,
25 is a power supply terminal (hereinafter, also referred to as a power supply point), 26 is a radio circuit, 27 is a radio housing, and thus the conventional whip antenna has a whip antenna that is pulled out so that good characteristics can be obtained when it is pulled out. The matching circuit was designed so that matching could be achieved at the lower end. Therefore, as in the current distribution 28 shown in FIG. 10A, a good sinusoidal current distribution can be obtained at the time of extraction.

This is also the case with a coil-loaded whip antenna as shown in FIG. In the figure, 2
Reference numeral 1 represents a linear whip antenna element, and 22 represents a coil. In this case as well, since it is designed to have the best characteristics when the whip antenna is pulled out, a good current distribution is obtained in the state shown in (a). can get.

[0005]

In the portable radio having the structure shown in FIG. 10 described above, when the linear whip antenna element is housed, the current distribution 29 has very little disturbance as shown in FIG. 10 (b). Become. This is designed so that it can be matched with the antenna drawn out by the matching circuit, and therefore, the feed point 25 with the whip antenna element 21 when housed.
This is because the impedance does not match, and sufficient power cannot be supplied to the antenna. In particular, since the antenna element housed therein is buried in the metal inside the housing, the impedance becomes low, and even if sufficient power is supplied to the antenna, the radiation from the antenna hardly reaches the outside of the housing.

Also in the portable wireless device having the structure shown in FIG. 11, the impedance at the antenna feeding terminal does not match,
The radiation characteristics of the antenna are greatly degraded. The current distributions when the antenna is pulled out and when the antenna is housed are as shown in FIGS. However, in this case, unlike the case of FIG. 10, since the coil portion is projected from the housing even when the whip antenna is housed, radiation occurs from that portion. However, this is quite small due to the impedance mismatch at the feed points.

Further, in these examples, only the case of the 1/2 wavelength type whip antenna has been described, but the 1/4 wavelength whip antenna also has the same drawback. In the example of FIG. 10, when the actual volume is measured by a portable wireless device having a capacity of about 400 cc, the gain when the whip is pulled out is −2 dBd (dipole ratio), whereas the gain when stored is −20 dBd.
Therefore, it was actually measured that the characteristics were significantly deteriorated.

As described above, in the conventional portable radio device having the retractable whip antenna, the matching circuit is designed so that the characteristics are best when the whip antenna is pulled out. There was a problem that power could not be supplied to the antenna.

The present invention has been made in order to solve such a conventional problem, and it is possible to obtain a good radiation characteristic even when the antenna is housed in the radio housing. The purpose is to provide a portable wireless device.

[0010]

According to the present invention, the above-mentioned problems are solved by the means described in the claims.

That is, the invention of claim 1 can be housed in a radio casing, and its electrical length is approximately 1 of the antenna resonance wavelength.
An antenna element corresponding to an integral multiple of / 2, a power supply terminal A placed on a side of the radio housing close to the antenna element outlet and electrically contacting the antenna element via a slider, and the power supply terminal A. A power supply terminal B placed on the side farther from the terminal A than the antenna element outlet and electrically contacting the antenna element via a slider, and a branch circuit for bifurcating input / output to / from the antenna of the radio device. And one of the circuits branched by the branch circuit is connected to the feeding terminal A directly or via a matching circuit a for matching the input / output impedance of the radio device and the current node impedance of the antenna element. , The other circuit branched by the branch circuit is through a matching circuit b for matching the input / output impedance of the radio with the current antinode impedance of the antenna element,
Alternatively, when the antenna element is directly connected to the power feeding terminal B and the antenna element is pulled out from the housing, the power feeding terminal A comes into contact with the current node of the antenna element, and the power feeding terminal B is opened, so that the antenna element is placed in the housing. The mobile wireless device has a structure in which the power supply terminal B contacts the current antinode of the antenna element when stored.

According to a second aspect of the present invention, in the portable wireless device having the above structure, when the wireless device antenna element is housed in the wireless device housing, one end, which is the base of the antenna element, is electrically connected to the ground circuit of the wireless device. The portable wireless device is configured so that a contact to be connected is provided and a short-circuited parallel two wire of ¼ wavelength is formed between the contact and the power supply terminal B.

[0013]

In the portable wireless device of the present invention, the power supply terminals are provided at two positions as the power supply terminal A and the power supply terminal B, and when the antenna element is pulled out from the wireless device housing and used, the power supply terminal A is the current of the antenna element. When the antenna element is housed in the radio casing and is used, the power feeding terminal B acts so as to come into contact with the current antinode of the antenna element to feed electric power. Therefore, the antenna element is placed inside the radio casing. Good radiation characteristics can be obtained even in the housed state.

Further, in the invention of claim 2, further,
When the antenna element is housed in the radio housing, one end of the antenna element farthest from the antenna outlet of the radio housing is electrically connected to the ground circuit of the radio equipment to short-circuit a quarter wavelength parallel. By using two wires, the impedance is made infinite and the current is cut off, whereby an operation equivalent to a 1/4 wavelength whip antenna from the feeding terminal B to the other end of the antenna element is performed.

[0015]

1A and 1B are views showing a first embodiment of the present invention. FIG. 1A shows a state when a whip antenna is pulled out, and FIG. 1B shows a state when a whip antenna is stored. In the figure, 1 is a linear antenna element having a coil loaded at its tip, 2
Is a matching circuit b, 3 is a matching circuit a, 4 is a power supply line, 5 is a power supply terminal A, 6 is a power supply terminal B, 7 is a wireless circuit, 8 is a ground level of a wireless device or a wireless device housing, In the following description, the power supply terminals indicated by numerals 5 and 6 are also referred to as power supply points.

Since this embodiment has such a structure, the lower end of the antenna element (linear metal + coil) 1 contacts only the feeding terminal A5 when the whip antenna shown in FIG. When the whip antenna shown in FIG. 3B is stored, only the coil portion projects from the housing,
The power feeding terminal A5 and the power feeding terminal B6 are in contact with the antenna element 1.

The situation of these current distributions is shown in FIG. In the figure, 9 indicates a current distribution when the whip antenna is pulled out, and 10 indicates a current distribution when the whip antenna is housed. When the antenna is pulled out as shown in FIG. 9A, the feeding terminal A is passed through the matching circuit a3 from the lower end.
Powered by 5. And the antenna element part is about 1
Since it resonates at the / 2 wavelength, the current distribution is as shown in 9. In this case, the power feeding terminal B6 does not contact the antenna element 1 at all, so that the antenna characteristics are not affected. Also,
Since a very short open line is connected in parallel to the power supply line from the wireless device, the impedance of the line hardly changes.

On the other hand, when the antenna is housed as shown in FIG. 2B, the feeding terminal B6 is in contact with a point corresponding to an electrical length of a quarter wavelength from the upper end of the antenna element. Therefore, the power is fed from the feeding point 6, and the same operation as that in the case where there are two upper and lower 1/4 wavelength whip antennas is performed. At this time, the matching circuit b2 functions to match the impedance of the radio device and the feeding impedance of the 1/4 wavelength whip antenna. Then, since the coil portion protrudes from the housing, the coil portion emits light. In this case, since the feeding point 5 has a high impedance, it does not match the low antenna impedance at this point and is in contact with the antenna element 1, but does not disturb the current distribution. In other words, the current distribution is as shown in 10, and the radiation is strong even during storage.

The actual measurement results of the characteristics of this embodiment will be described below. The length of the linear metal part of the antenna element is 80m
m, coil part diameter 4 mm, length 13 mm, number of turns 1
6 times, the height of the housing is 130 mm, the width is 55 mm, and the thickness is 2
4 mm, a π match circuit is used as the matching circuit a,
The matching circuit b is not provided because the input / output impedance of the wireless device is 50Ω.

FIG. 3 shows the return loss characteristics when the antenna is pulled out and when the antenna is housed. When the antenna was stored, only the coil part was projected from the case. When the whip antenna is pulled out, the resonance frequency is 904 MHz as shown in Fig. 4 (a).
The return loss was −38 dB (VSWR <1.1), and the resonance frequency moved to 983 MHz when the antenna was housed, as shown in FIG. 7B, but it was −9 when the resonance frequency when the antenna was pulled out was 904 MHz. 0.5 dB (V
A return loss of about SWR <2) was obtained. That is, with this structure, it is found that a sufficiently low return loss is obtained both when the antenna is pulled out and when the antenna is housed, which indicates that sufficient power is supplied to the antenna element even when the antenna is housed. There is.

Therefore, in order to confirm that the radiation is actually emitted, the result of measurement of the radiation pattern on the horizontal plane in the upright state is shown in FIG. Here, (a) shows the state when the whip antenna is pulled out, (b) shows the state when the conventional antenna is stored, and (c) shows the state when the antenna of this embodiment is stored, where 11 is the Eθ component and 12 is the Eφ component. Is represented.

As is apparent from this figure, in the conventional case,
It radiates enough when the antenna is pulled out, but when the antenna is housed, the radiation characteristic deteriorates considerably. On the other hand, in the case of the present embodiment, although the pattern shape has a deviation, the radiation is quite strong. Recognize. When the level average of these patterns is considered as the gain, (a) is -1 dBd.
(Dipole ratio), (b) is -13 dBd, (c) is-
It was 4.5 dBd. From this result, it can be seen that according to the present invention, it is possible to realize a portable wireless device having good radiation characteristics even when the whip antenna is housed.

FIGS. 5A and 5B are views showing a second embodiment of the present invention, in which FIG. 5A shows a state when the whip antenna is pulled out and FIG. 5B shows a state when the whip antenna is stored, and 13 denotes a linear antenna element. ing. Other numeral marks are the same as those in FIG. In this case also, the structure is almost the same as that of the first embodiment,
In order to operate the linear whip antenna as a quarter-wave whip antenna during storage, the feeding point 6 must be located approximately at the center of the linear antenna element 13, so the antenna element 13 must be completely stored. I can't.

However, even in the case of a linear antenna element not loaded with a coil, similar effects can be obtained by using substantially the same structure. Also in this case, it is possible to realize a portable wireless device having good radiation characteristics when the whip antenna is stored.

6A and 6B are views showing a third embodiment of the present invention, in which FIG. 6A shows a state when the whip antenna is pulled out, and FIG. 6B shows a state when the whip antenna is stored. In the figure, 14 is a contact terminal C, 15 is a metal near the antenna, and other numerals are the same as in FIG. In this embodiment, the contact terminal C is provided so that the lower end of the antenna is short-circuited with the housing metal when the antenna is housed.

7A and 7B show changes in the current distribution when the antenna of this embodiment is pulled out and the antenna is housed.
When the antenna is pulled out, it is the same as that of the conventional 1/2 wavelength whip antenna when the antenna is pulled out, but since the lower end of the whip antenna is short-circuited by the contact terminal C when the antenna is housed, the feeding point 6 The impedance seen from the bottom is infinite, and current flows only in the upper part.
This mechanism is shown in FIG. This figure is a horizontal view of FIG.

By feeding power from the feeding point 6, the 1/2 wavelength whip antenna is operated as a 1/4 wavelength whip antenna when the antenna is housed. In the first embodiment, FIG.
As shown in, the two 1/4 wavelength whip antennas, the upper and the lower, were fed from the feeding point 6. On the other hand, as shown in FIG. 8, in an actual wireless device, the housing metal 15 is located near the housed quarter-wave whip antenna, so that the efficiency of the lower antenna may deteriorate.

Furthermore, if the housing metal 15 is very close, it is the same as that when a capacitor is inserted in parallel at the feeding point 6, and impedance matching may not be achieved. Therefore, in this example, the lower end of the antenna is short-circuited as shown in FIG. The short-circuited two parallel lines of 1/4 wavelength have an infinite impedance regardless of the value of the characteristic impedance of the line, so that the current flows only from the feeding point 6 to the left side. Therefore, FIG.
As in (b), a current flows only in the upper 1/4 wavelength whip antenna, and the same operation as the single 1/4 wavelength whip antenna is performed.

The result of actual operation confirmation of this antenna will be described. The radio has the same structure as in the first embodiment, and the antenna element and the housing are spaced from each other by about 2 mm when the antenna is housed, and the lower end of the antenna is short-circuited. This return loss characteristic is shown in FIG. in this way,
Resonance frequency 904 when pulled out
It can be seen that the return loss is close to 8 dB at MHz and resonates even when the antenna is housed. Further, from the experimental results of the first embodiment, it can be inferred that the radiation characteristic is good as long as resonance is achieved.

That is, with the configuration of this embodiment, it is possible to realize a portable radio device having good antenna radiation characteristics when the antenna is housed. In addition, although the length of the antenna element is ½ wavelength in the above embodiments, the same effect is obtained even when the length of the antenna element is an integral multiple of ½ wavelength. It is clear that can be obtained.

[0031]

As described above, according to the present invention,
In the portable wireless device, there is an advantage that good radiation characteristics can be obtained not only when the antenna element is pulled out from the housing but also when the antenna element is housed in the housing.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a current distribution of the antenna of the first embodiment.

FIG. 3 is a diagram showing return loss characteristics when the antenna of the first embodiment is pulled out and stored.

FIG. 4 is a diagram showing radiation pattern characteristics when the antenna of the first embodiment is pulled out and stored.

FIG. 5 is a diagram showing a second embodiment of the present invention.

FIG. 6 is a diagram showing a third embodiment of the present invention.

FIG. 7 is a diagram showing a current distribution of the antenna of the third embodiment.

FIG. 8 is a diagram illustrating a structure around an antenna according to a third embodiment.

FIG. 9 is a diagram showing a return loss characteristic when the antenna according to the third embodiment is housed.

FIG. 10 is a diagram showing an example of a conventional portable wireless device.

FIG. 11 is a diagram showing another example of a conventional portable wireless device.

[Explanation of symbols]

1 antenna element 2 Matching circuit a 3 Matching circuit b 4 power lines 5 Power supply terminal A (power supply point) 6 Feeding terminal B (feeding point) 7 wireless circuit 8 radio housing 9 Current distribution when the whip antenna is pulled out 10 Current distribution when storing the whip antenna 11 Eθ component 12 Eφ component 13 Wire antenna element 14 Contact terminal C 15 Metal near the antenna 16 Current distribution 21 Wire Whip Antenna Element 22 coils 23 Matching circuit 24 50Ω system coaxial line 25 power supply terminal 26 wireless circuits 27 radio housing 28 Current distribution when the whip antenna is pulled out 29 Current distribution when storing whip antenna

Claims (2)

[Claims] 1. An antenna element which can be housed in a radio housing and has an electric length corresponding to an integral multiple of approximately 1/2 of an antenna resonance wavelength, and an antenna element which is placed near the antenna element outlet of the radio housing. And a power supply terminal A that is in electrical contact with the antenna element through a slider, and a terminal farther from the power supply terminal A with respect to the antenna element outlet, and the antenna element is connected through the slider. It is equipped with a power supply terminal B that makes electrical contact and a branch circuit that branches the input and output to and from the antenna of the radio device. Via a matching circuit a for matching the local impedance, or
The other circuit, which is directly connected to the power supply terminal A and branched by the branch circuit, is passed through a matching circuit b for matching the input / output impedance of the radio device and the current abdominal impedance of the antenna element, or
When the antenna element is directly connected to the power feeding terminal B and the antenna element is pulled out from the housing, the power feeding terminal A contacts the current node of the antenna element and the power feeding terminal B
Is in an open state, and when the antenna element is housed in a housing, the power supply terminal B is in contact with the current antinode of the antenna element. 2. When the antenna element is housed in a radio housing, one end which is a base portion of the antenna element is provided with a contact electrically connected to a ground circuit of the radio, and the contact and the feeding terminal B are connected. 2. The portable wireless device according to claim 1, wherein the short-circuited parallel two lines of ¼ wavelength are formed between the two.