KR100459969B1 - Portable Wireless Communication Device - Google Patents

Abstract

A small flat antenna mounted on a portable wireless communication device is available for a narrow bandwidth, and the resonance frequency of the flat antenna changes due to the interference between the flat antenna and a peripheral dielectric such as a housing and a human body. As a result, the reception sensitivity and transmission efficiency of the antenna are impaired. Communication portions (consisting of coaxial lines or microstrip lines) are arranged in portable radio communication devices having circularly polarized antennas for satellite communication, whereby a suitable distance between the housing and antenna of the portable radio communication device and between the human body and the antenna is ensured. Will be provided.

Description

Portable wireless communication device

The present invention relates to a portable wireless communication device having a circularly polarized antenna effective for satellite communication.

In mobile communications via portable radio communication devices (cellular phones) and the like, linearly polarized waves belonging to the frequency bands of 800 MHz, 1.5 GHz and 1.9 GHz are currently used. Portable telephones using medium or low satellites have recently been proposed by communication system companies, and the following frequency band allocation systems have been planned for such mobile satellite communications. One system allocates a frequency band of 1.6 GHz for uplink communications from terrestrial mobile phones to satellites and a 2.4 GHz frequency band for downlink from satellites to terrestrial mobile phones. The other system allocates a frequency band of 1.6 GHz for both uplink and downlink communications. In this communication, circular polarization is generally used to ensure the quality of wireless communication lines.

As shown in FIG. 7, as an exemplary antenna structure, a folding antenna array 25 has been proposed ("Non-geostationary Satellite Communication Systems of the World"). , ITU Research, No.261 / 262, New Japan ITU Society, August 1993, p. 36). The folding antenna array 25 includes a microstrip flat antenna 22 (hereinafter referred to as "transmission flat antenna") and a receiving microstrip flat antenna 23 (hereinafter referred to as "reception flat antenna"). Is used for satellite communications.

The folding antenna array 25 will be described. For the sake of explanation, the structure proposed by the ODYSSEY system (TRW Corp., USA) published in the above-mentioned document "ITU Research" is selected as an example. The portable telephone 92 shown in FIG. 7 has a folding antenna array 25 having a transmit flat antenna 22 and a receive flat antenna 23 arranged on a dielectric. The folding antenna array 25 may be arbitrarily folded relative to the portable telephone 92 at a folding angle α in the range of 0 to 180 degrees via hinges 85.

In this case, the transmit flat antenna 22 and the receive flat antenna 23 communicate with the satellite using the frequencies f1 and f2, respectively. In the case of a satellite communication system using the same frequency f1 for both transmission and reception, only the transmission flat antenna 22 can be used for both transmission and reception. In general, the frequency f1 uses a frequency band of 1.6 GHz, and the frequency f2 uses a frequency band of 2.4 GHz.

However, a small flat antenna using a dielectric sheet has a narrow bandwidth, and the resonant frequency of the flat antenna changes due to interference between itself and surrounding dielectrics such as the housing and the human body. As a result, the reception sensitivity and transmission efficiency of the antenna are impaired. In particular, when communicating with low orbit satellites, the loss of antenna gain caused by the human head is raised as a problem.

In addition, when the main beam is directed towards the zenith (at an elevation angle of 90 °), the communication sensitivity at the low angle is lost in the flat antenna. The use of either a flat antenna or a helical antenna has been proposed for mobile communication via a communication satellite, but due to the limitation of directivity specific to each type of antenna, when the satellite is at elevation angles or the satellite is at elevation angles Satisfactory communication sensitivity can only be obtained when in the field.

1 illustrates a portable wireless communication device that is an embodiment of the invention.

2 shows a state in which radiation from an antenna is not shielded by the head of a human body through the use of a portable telephone which is an embodiment of the present invention.

3A illustrates an antenna having a communication portion to a four-wire helical antenna;

3B illustrates an antenna having a communication portion to a monofilar helical antenna;

4 shows another embodiment of the invention in which a portable radio communication device is equipped with a flat antenna means and a helical antenna means;

Fig. 5 is a block diagram showing an antenna circuit for helical antenna means and flat antenna means.

6A shows the relative power of the main beam of circularly polarized waves of a flat antenna;

6B shows the relative power of the main beams of circularly polarized waves of the helical antenna;

6C shows the relative power of the synthesized main beams of FIGS. 6A and 6B.

7 illustrates a conventional portable wireless communication device.

The present invention has been made to overcome the above-mentioned problems by preventing the antenna element from approaching the human body (especially the head) when the user uses the portable wireless communication device. That is, in the circularly polarized antenna mounted in the portable radio communication apparatus, a communicating section is arranged between the portable radio communication apparatus and the antenna element.

In addition, the present invention provides two circularly polarized antennas in a portable wireless communication device, wherein the main beam radiation direction of one of these antennas is configured differently from the other.

1 shows an embodiment of the present invention. Reference numeral 5 denotes a communication portion composed of a coaxial line or a microstrip line. The circularly polarized helical antenna 14 composed of the coaxial line 9 or the like is separated from the mobile phone 92 by the communicating section 5. Note that reference numeral 81 denotes a display unit, 82 a receiver, 83 an operation unit, and 84 a transmitter.

First, the operation and characteristics of the helical antenna 14 generating circular polarizations for satellite communication will be described. As the helical antenna 14, for example, a 2-wire helical antenna (published in Japanese Unexamined Patent Publication No. 3-274904) and the like are known. This two-wire helical antenna is used in this embodiment. The helical antenna 14 comprises a coaxial line 9, which serves as a radiating element, and a conductor 8, which conductor 8 has a core conductor and a feed point of the coaxial line 9 which serves as a radiating element. (7, electrically connect the conductor 8 at the feed point, and electrically connect the conductor 8 at the helix end with the outer conductor of the coaxial line 9 serving as the radiating element Connect. Reference numeral 11 denotes a dielectric cylinder in which the coaxial line 9 and the conductor 8 are wound in a spiral.

The operation will be described based on the high frequency current flowing through the helical antenna 14. The feed point 7 of the helical antenna 14 is located on top of the antenna. To the outer conductor of the coaxial line 9 which serves as a radiating element, nothing which serves as an antenna element is connected. The high frequency current coming from the core conductor of the coaxial line 9 at the feed point 7 flows upwards from the spiral end 6 on the outer wall side of the outer conductor of the coaxial line 9, and the outer conductor of the coaxial line 9. The current flows in the opposite direction on the inner wall side of the. Therefore, no high frequency current flows through the outer conductor of the coaxial line 9 in the nominal terms. As a result, the high frequency current becomes a loop current. Since the conductor 8 and the coaxial line 9 are wound spirally around the dielectric cylinder 11, a high frequency current generates an electric field along the helix and radiates circularly polarized light.

Next, during the operation of connecting the helical antenna 14 to the portable telephone, the radiation pattern is disturbed when the radiating element approaches the telephone housing. As a result, the performance of the antenna, which is an independent body, is impaired, and therefore, the performance of matching the electromagnetic characteristics of both the housing and the antenna is required. This action reduces productivity. In addition, the radiating element of the antenna adjacent to the telephone housing becomes closer to the head of the human body, which makes it difficult for the antenna to perform what is expected to be performed. In order to overcome this problem, the communication section 5 is arranged in the antenna holder 10, so that the antenna can perform what is expected to be performed by reducing the interference between the helical antenna 14 and the telephone housing. The sliding connector 13 is arranged on the upper right surface of the mobile telephone 92, and the sliding connector 12 is arranged on the side of the communication section 5, so that the antenna holder 10 is releasable. The length of the communication section 5 is designed to be about 20% to 100% of the physical length of the radiating element of the circularly polarized antenna, or is designed to be about 0.1λ to 0.5λ (wavelength) of the operating wavelength of the radiating element of the circularly polarized antenna. .

Since the communicating portion 5 is arranged in the antenna holder 10, the distance between the telephone housing and the helical antenna 14 and the distance between the head of the human body and the helical antenna 14 can be increased, which is an appropriate antenna. Allow performance to be maintained. 2 shows a state in which radiation from the antenna is not shielded by the head of the human body through the use of the cellular phone according to the present embodiment. It can be understood from this figure that the antenna gain at low elevation angles necessary for communicating with a low orbit satellite is not lost.

Although two-wire helical antennas have been used in the above embodiments, other types of helical antennas may also be used. For example, a monowire consisting of a four-wire helical antenna 15 having four conductors as a radiating element as shown in FIG. 3A, and a ground plane 17 and a conductor 16 as shown in FIG. 3B. (1-wire) helical antenna or the like can provide similar advantages as long as the communication section 5 is arranged in the antenna holder 10.

Note that an optimal type of helical antenna may be selected depending on the system in which the portable radio communication device is used. The helical antenna may be rotatable or pull-out such that the helical antenna may be housed within the housing of the wireless communication device.

In addition, although a coaxial line or a microstrip line is accommodated in the communication part 5 arrange | positioned at the antenna holder 10 in the above example, this invention is not limited to this example, The communication part 5 is a coaxial line and a microstrip It may also be applied to a case composed of lines or the like. In addition, although the antenna is designed to be releasable through the sliding connector 13 and the sliding connector 12, the present invention is not limited to this design but can also be applied to a fixed antenna design as long as the communication section 5 is provided.

4 shows another embodiment of the present invention. Portions corresponding to the embodiments shown in FIGS. 1 to 3 are given the same reference numerals, and detailed description thereof will be omitted herein. 4, reference numeral 40 denotes a flat antenna means; 14, helical antenna means; 92 denotes a portable radio communication device (mobile phone). The flat antenna means 40 is arranged in the upper surface portion of the housing of the portable radio communication device 92, and the helical antenna means 14 is arranged in the upper side surface portion of the housing to extend upward. 5 is a block diagram illustrating a circuit of antennas. The signal synthesizer 32 is connected to the wireless communication unit 31. A signal selector may be used instead of the signal synthesizer 32. The two antennas have different main beam radiation directions, but have the same operating frequency band and the same circular polarization rotation direction.

The flat antenna means 40 is configured such that a patch-like conductor 2 is bonded to the upper surface of the dielectric sheet 3 and a ground plane (not shown) is bonded to the lower surface of the dielectric sheet 3. . Through holes (not shown) are disposed in the dielectric sheet 3. The feed pin 1 is inserted into the through hole, whereby the feed pin 1 is electrically connected to the patch-like conductor 2. At this time, the conductor portion around the through hole is removed to prevent the feed pin 1 from contacting the ground plane. Similarly, the through holes are arranged in the conductor plate 50 and the conductor plate 50 is arranged so as not to be in electrical contact with the feed pin 1. The conductor plate 50 is slightly larger in size than the flat antenna means 40. The most common form of patched conductor 2 is substantially square. The patch-like conductor 2 resonates at a low frequency in the direction of the long side and at a high frequency in the direction of the short side. That is, the patch-like conductor 2 resonates at two different frequencies and operates as a circularly polarized antenna between two different frequencies. Impedance matching is provided by adjusting the position of the feed pin 1.

The main beam of the flat antenna means 40 is generally directed towards the zenith (FIG. 6A), thus limiting design freedom (with some design freedom depending on the size of the conductor plate 5). On the other hand, great design freedom is given to the helical antenna means 14. It is possible to select the winding conditions such that the main beam is directed at the bottom angles (FIG. 6B). By combining these two types of directional antennas and arranging them in a portable wireless communication device in the manner as shown in Fig. 4, stable communication sensitivity can be provided in the range from the elevation (towards Zenith) to the elevation angle (Fig. 4). 6c).

In addition, the helical antenna means 14 shown in FIG. 1 is housed in and held in an antenna holding tube 10. Helical antenna means (at a position away from the top of the portable radio communication device 92 while inserting a signal transmission path (coaxial line 4 or microstrip line) between the portable radio communication device 92 and the helical antenna means 14). 14 is maintained, and the signal transmission path is derived from the radio communication unit 31. Since the main beam of the helical antenna means 14 (two-wire helical antenna) is directed at an elevation angle, the portable radio communication device 92 so that the loss of antenna gain caused by the head of the human body is separated from the portable radio communication device 92. Can be prevented by keeping the helical antenna means 14 above.

Although square micro strip flat antennas are illustrated as flat antennas in the above embodiments, triangular, pentagonal or circular micro strip antennas may be used. Also, while one-point back feeding is illustrated as a feed system, two-point back feeding, one-point feeding, or two-point feeding around the patch may be used. In addition, a spiral antenna may be used.

Although a 2-wire helical antenna is illustrated as the helical antenna, the 4-wire antenna shown in FIG. 3A, the mono-piler (1-wire) helical antenna shown in FIG. 3B, the 3-wire helical antenna, and the like according to the communication satellite system. It may be chosen.

Further, by arranging the flat antenna on the upper end of the helical antenna fixed to the antenna holding tube, the loss of the antenna gain of the flat antenna caused by the head of the human body can be prevented. A signal transmission path is provided to the antenna holding tube for supplying a signal to the flat antenna.

As described above, the present invention is characterized by providing a communication unit for transmitting a signal between the portable radio communication device and the circularly polarized antenna disposed on the portable radio communication device. As a result of this arrangement, satisfactory satellite communication is possible as well as productivity can be improved.

In addition, in a satellite communication system requiring satellite handover (switching from one satellite to another) at elevation angles, the reliability of communication at elevation angles can be improved.

Regardless of the elevation angle of the communication satellites viewed from the ground, satisfactory communication sensitivity can be easily obtained. In addition, handover (and vice versa) from the high-angle satellite to the low-angle satellite can be implemented smoothly.

Claims (5)

A portable radio communication device, A communication unit arranged on an upper portion of a housing of the wireless communication device to transmit a signal, the housing configured to receive a radio communication section therein; A chokeless circularly polarized antenna held at one end of the communicating portion such that all radiating elements are kept away from the housing, wherein the main beam of the circularly polarized antenna is directed at a low elevation angle, Equipped with the circularly polarized antenna, The radiating element of the circularly polarized antenna has an antenna gain at low angles for communication with satellites of low earth orbit, And wherein said communicating portion maintains said circularly polarized antenna at a height such that communication with a satellite at a lower angle is not substantially disturbed by a user's head. A portable radio communication device, A communication unit arranged on an upper portion of a housing of the wireless communication device to transmit a signal, the housing accommodating a wireless communication unit therein; A first chokeless circularly polarized antenna held at one end of the communicating portion such that all radiating elements are kept away from the housing and the main beam is directed at an elevation angle; The main beam has a second choke circularly polarized antenna directed at elevation angles, The radiating element of the circularly polarized antenna has an antenna gain at low angles for communication with satellites of low earth orbit, And wherein said communicating portion maintains said circularly polarized antenna at a height such that communication with a satellite at a lower angle is not substantially disturbed by a user's head. The method of claim 2, The second circularly polarized antenna is a flat antenna, the first circularly polarized antenna is a helical antenna, and a conductor surface of a patch of the flat antenna and an upper end of the helical antenna are upwardly relative to a housing of the wireless communication device. Oriented, portable wireless communication device. The method of claim 3, wherein And the flat antenna is secured to an upper end of the helical antenna. The method of claim 3, wherein And the helical antenna is supported on top of the housing via a signal transmission path between the helical antenna and the top of the housing to be spaced apart from the top of the housing of the wireless communication device.