Antenna equipment and mobile communication equipment

Abstract: A high gain antenna equipment is provided by improving the gain with an optimal impedance matching with an antenna element (3) in a stored state as well as in an extended state. The antenna equipment is provided with a radio communication device (4) housed in a case (2), a pullout type antenna element (3), a coil (11) acting as a matching circuit element in an extended state of the antenna element (3) and as a helical antenna in a stored state, and a switch (12) connected to the coil (11) at one end which is brought into contact at the other end with a ground terminal when the antenna element (3) is in an extended state and which is brought into contact with an open terminal when the antenna element (3) is in a stored state.

Description: The present invention relates to antenna equipment and a communication method, which are applicable to any portable radio communication device used specifically in a mobile environment such as a motor vehicle. The European Patent application EP-A 0 523 867 discloses an antenna assembly comprising an elongate radiating element movable between a retracted position and an extended position. A second substantially planar radiating element extends transversely to the elongated element and is incorporated into the assembly housing. In retracted position of the elongate element, the planar element acts as the antenna. Figs. 51 and 52 show cross sectional views of another conventional antenna equipment, provided in a radio communication device, as disclosed in JP-A-160101/1989. Referring to these figures, a case 22 of a radio communication device 21 houses a pullout type long cylindrical antenna element 23, a radio circuit 24 and a connection terminal 25. The connection terminal 25 is electrically connected to the radio circuit 24 and is also selectively connected to connection terminals 23a and 23b of antenna element 23. Figs. 53 and 54 show connection diagrams of the conventional antenna equipment of Figs. 51 and 52, respectively. Figs. 55A and 55B show an example of a conventional radio communication device provided with conventional antenna equipment. As shown in Figs. 55A and 55B, the radio communication device 21 comprises a case 22 provided with an antenna element 23. On the front side, there is provided a receiver 121, a transmitter 122, dial pushbuttons 131a, function keys 131b and a display 133 for displaying alphanumeric characters and symbols. Operation of the conventional antenna equipment is now discussed. With reference to Figs. 51 and 53, the antenna element 23 is pulled out of the case 22 of the radio communication device 21 to an extended position. A connection terminal 23a at a lower end of the antenna element 23 is brought into contact with the connection terminal 25 to connect the extended antenna element 23 to the radio circuit 24. With reference to Figs. 52 and 54, the antenna element 23 is stored in the radio communication device 21 in a retracted position. A connection terminal 23b at an upper end of the antenna element 23 is brought into contact with the connection terminal 25 to connect the retracted antenna element 23 to the radio circuit 24. Thus, the conventional antenna equipment is designed to selectively connect the antenna element 23 to the connection terminal 25 not only by way of the connection terminal 23a at the lower end in an extended state of the antenna element but also by the connection terminal 23b at the upper end in a retracted state of the antenna element. Therefore, the conventional antenna equipment can work as an antenna in a stored, retracted state of the antenna element 23 in the radio communication device 21. The radio circuit 24 includes a matching circuit, which is not illustrated in the figures, for an optimal matching with the antenna element 23 in an extended state. According to the conventional antenna equipment, the single antenna element 23 is required to work in both an extended state and in a stored state. As a result, an optimal impedance matching can be achieved with the antenna element 23 in an extended state. On the other hand, however, with the antenna element 23 in a stored state an impedance mismatching may occur since the radio circuit 24 and the antenna element 23 are too close to each other, as shown in Fig. 52 where they are only separated by a small distance W , causing the antenna element 23 to be grounded. This may lead to poor gain performance of the antenna. One of the objects of the invention is to provide antenna equipment which can achieve an optimal impedance matching having an improved gain performance with an antenna element in a stored state as well as in an extended state. According to the present invention, an antenna equipment is provided as defined in claim 1. Acting means include a first terminal which is coupled to one end of the first antenna element when the first antenna element is in the stored position, and which is coupled to a second end of the first antenna element when the first antenna element is in the extended position. The antenna equipment may further include a signal line connected between the first antenna element and the radio circuit. The signal line may be selected from the group comprising a coaxial strip line, a coaxial line, a strip line, a triplet line, a Lecher line, and a coaxial line having a predefined shaped shield. The acting means may be selected from the group comprising a coil, a meander board, a chip, a line element, and a board element. The second antenna element may be selected from the group of a helical antenna, a reverse L shaped line antenna, and a reverse L shaped board antenna. According to the present invention, a method of communication using antenna equipment is also provided as defined in claim 12. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below with reference to the accompanying drawings, wherein: Fig. 1A shows a side view of a radio communication device provided with antenna equipment according to a first embodiment of the present invention; Fig. 1B shows a front view of the radio communication device of Fig. 1A; Fig. 2 shows a sectional side view of the antenna equipment provided in the radio communication device of Figs. 1A and 1B with an antenna element in a stored state. Fig. 3 shows a sectional side view of the antenna equipment of Fig. 2 with the antenna element in an extended state. Fig. 4 shows a connection diagram of the antenna equipment of Fig. 3. Fig. 5 shows a connection diagram of the antenna equipment of Fig. 2. Fig. 6 shows a sectional side view of a connection terminal at a lower end of the antenna element of Fig. 2 illustrating a feed line. Fig.7 shows a flowchart illustrating the operation of the antenna equipment of Fig. 2. Fig. 8 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to a second embodiment of the present invention. Fig. 9 shows a sectional side view of the antenna equipment of Fig. 8 with the antenna element in an extended state. Fig. 10 shows a sectional side view of an antenna equipment provided in a radio communication device with an antenna element in an extended state according to a third embodiment of the present invention. Fig. 11A shows a sectional side view of a feed line (a strip line) of the antenna equipment of Fig. 10. Fig. 11B shows a B-B sectional front view of the feed line of Fig. 11A. Fig. 11C shows an A-A sectional front view of the feed line of Fig. 11A. Fig. 12 shows a perspective sectional view of a replacement feed line for that of Fig. 10. Fig. 13 shows another perspective sectional view of a replacement feed line for that of Fig. 10. Fig. 14A shows a sectional side view of a feed line of antenna equipment according to a fourth embodiment of the present invention. Fig. 14B shows a B-B sectional front view of the feed line of Fig. 14A. Fig. 14C shows an A-A sectional view of the feed line of Fig. 14A. Fig. 15A shows a front view of a feed line of antenna equipment according to a fifth embodiment of the present invention. Fig. 15B shows a side view of the feed line of Fig. 15A. Fig. 15C shows a B-B sectional front view of the feed line of Fig. 15B. Fig. 16A shows a front view of a replacement feed line for that of Fig. 15A according to the fifth embodiment. Fig. 16B shows a side view of the feed line of Fig. Fig. 16A. Fig. 16C shows a B-B sectional view of the feed line of Fig. 16C. Fig. 17 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to a sixth embodiment of the present invention. Fig. 18 shows an A-A sectional view of the antenna element, illustrating a feed line, of the antenna equipment of Fig. 17. Fig. 19 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to a seventh embodiment of the present invention. Fig. 20 shows a B-B sectional view of the antenna element, illustrating a feed line, of the antenna equipment of Fig. 19. Fig. 21 shows a sectional side view of an antenna equipment provided in a radio communication device with an antenna element in a stored state according to an eighth embodiment of the present invention. Fig. 22 shows a sectional side view of the antenna equipment of Fig. 21 with the antenna element in an extended state. Fig. 23 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to a ninth embodiment of the present invention. Fig. 24 shows a sectional side view of the antenna equipment of Fig. 23 with the antenna element in an extended state. Fig. 25 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to a tenth embodiment of the present invention. Fig. 26 shows a sectional side view of the antenna equipment of Fig. 25 with the antenna element in an extended state. Fig. 27 shows a sectional side view of a connection terminal at a lower end of the antenna element, illustrating a feed line, of the antenna equipment of Fig. 25. Fig. 28 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to an eleventh embodiment of the present invention. Fig. 29 shows a sectional side view of the antenna equipment of Fig. 28 with the antenna element in an extended state. Fig. 30 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in an extended state according to a twelfth embodiment of the present invention. Fig. 31 shows a sectional side view of a connection terminal at a lower end of the antenna element, illustrating a feed line, of the antenna equipment of Fig. 30. Fig. 32 shows a sectional side view of a connection terminal at a lower end of an antenna element, illustrating a feed line, of antenna equipment according to a thirteenth embodiment of the present invention. Fig. 33 shows a C-C sectional view of the feed line of the antenna equipment in Fig. 32. Fig. 34 shows a sectional side view of a connection terminal at a lower end of an antenna element, illustrating a feed line, of antenna equipment according to a fourteenth embodiment of the present invention. Fig. 35 shows a D-D sectional view of the feed line of the antenna equipment of Fig. 34. Fig. 36 shows a perspective sectional view of a replacement feed line for that of Fig. 34 according to the fourteenth embodiment. Fig. 37 shows a perspective sectional view of another replacement feed line for that of Fig. 34 according to the fourteenth embodiment. Fig. 38 shows a perspective sectional view of another replacement feed line for that of Fig. 34 according to the fourteenth embodiment. Fig. 39 shows a sectional side view of a connection terminal at a lower end of an antenna element, illustrating a feed line, of antenna equipment according to a fifteenth embodiment of the present invention. Fig. 40 shows an E-E sectional view of the feed line of the antenna equipment of Fig. 39. Fig. 41 shows an F-F sectional view of the feed line of the antenna equipment of Fig. 39. Fig. 42 shows a sectional side view of a connection terminal at a lower end of an antenna element, illustrating another feed line, of antenna equipment according to the fifteenth embodiment of the present invention. Fig. 43 shows an E-E sectional view of the feed line of the antenna equipment of Fig. 42. Fig. 44 shows an F-F sectional view of the feed line of the antenna equipment of Fig. 42. Fig. 45 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to a sixteenth embodiment of the present invention. Fig. 46 shows a sectional side view of the antenna equipment of Fig. 45 with the antenna element in an extended state. Fig. 47 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to a seventeenth embodiment of the present invention. Fig. 48 shows a sectional side view of the antenna equipment of Fig. 47 with the antenna element in an extended state. Fig. 49 shows a sectional side view of antenna equipment provided in a radio communication device with an antenna element in a stored state according to an eighteenth embodiment of the present invention. Fig. 50 shows a sectional side view of the antenna equipment of Fig. 49 with the antenna element in an extended state. Fig. 51 shows a sectional side view of conventional antenna equipment provided in a conventional radio communication device with an antenna element in an extended state. Fig. 52 shows a sectional side view of the conventional antenna equipment of Fig. 51 with the antenna element in a stored state. Fig. 53 illustrates a connection diagram of the conventional antenna equipment of Fig. 51. Fig. 54 illustrates a connection diagram of the conventional antenna equipment of Fig. 52. Fig. 55A shows a side view of a conventional radio communication device provided with the conventional antenna equipment. Fig. 55B shows a front view of the radio communication device of Fig. 55A. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1. A first embodiment of the invention will be described in reference to Figs. 1 through 7. Figs. 1A and 1B show a radio communication device provided with antenna equipment according to this embodiment. Referring to the figures, the radio communication device 1 has an antenna element 3 for transmitting and receiving electric wave signals, a receiver 121, a transmitter 122, dial pushbuttons 131a, function keys 131b, a display 133 for displaying alphanumeric characters and symbols, and a cap 100. The cap 100 supports the antenna element 3 and contains therein a coil 11 and a connection terminal 5. Figs. 2 through 6 show simplified diagrams of the radio communication device. Referring to the figures, the radio communication device 1 includes a case 2 for housing the radio communication device 1, a pullout type cylindrical antenna element 3, a connection terminal 3a at a lower end of the antenna element, a connection terminal 3b at an upper end of the antenna element, a radio circuit 4, and the connection terminal 5 which is brought into contact with the connection terminal 3a at the lower end of the antenna element in an extended state and with the connection terminal 3b at the upper end of the antenna element in a stored state. A coil 11 is connected to the connection terminal 5 at one end and to a switch 12 at the other end. The switch 12 is brought into contact with a ground terminal connected to a ground of the radio circuit 4 with the cylindrical antenna element 3 in an extended state as shown in Fig. 3. The switch 12 is brought into contact with an open terminal or open circuit in a stored state of the cylindrical antenna element 3 as shown in Fig. 2. A feed (coaxial) line 13 is connected to the connection terminal 3a at the lower end of the antenna element as shown in Fig. 3. The feed line 13 is also connected to the radio circuit 4 at the other end thereof. A feed line storage compartment 14 stores the feed line 13 in a stored state of the cylindrical antenna element. A stopper 16 holds the connection terminal 3a at the lower end of the antenna element 3 and prevents the antenna element 3 from coming out of the device in an extended state of the cylindrical antenna element 3. A stopper 15 holds the connection terminal 3a at the lower end of the antenna element 3 to stabilize the element in a fixed position with the cylindrical antenna element 3 in a stored state. The stopper 15 protects the feed line 13 from possible damage with the antenna element 3 in a stored state. Fig. 6 shows a detailed cross sectional partial view of the antenna element at the lower end. Referring to Fig. 6, a coaxial feed line 13 has a center core line 3d surrounded by an insulator 3j. The insulator 3j is surrounded by a shield (ground) 3i. The shield is surrounded by an outer cover 3k of the coaxial line 13. The antenna element 3 is connected at the lower end 3a to the coaxial line 13 via a metal contact 3e. Consequently, a signal on the core line 3d is transferred from the feed line side to the antenna element side via the metal contact 3e. The antenna element 3 is surrounded by an outer cover 3c. The coaxial feed line 13 is bonded with the metal contact 3e by an adhesive 3f. The shield 3i and the outer cover 3k reach as far as the adhesive is provided. The insulator 3j and the core line 3d are provided through the antenna element at the lower end via the metal contact 3e. When the cylindrical antenna element 3 is pulled out, the stopper 16 blocks the connection terminal 3a at the lower end of the antenna element 3 to prevent the antenna element 3 from coming out of the device. The physical contact between the stopper 16 and the connection terminal 3a causes a frictional resistance, which holds the antenna element 3 in an extended position. The feed line 13 is fed out from the feed line storage compartment 14 as the antenna element 3 is pulled out of the device. In order to achieve an optimal impedance matching of the antenna element 3, the connection terminal 3a is brought into electrical contact with the coil 11 and the switch 12 through the connection terminal 5. The switch 12 detects the motion of the antenna element 3 mechanically or electrically. Depending on the direction of motion, the switch 12 comes into contact either with the open terminal or the ground terminal connected to the shield case 2 of the radio circuit 4. With the antenna element 3 in an extended state, for example, the switch 12 comes into contact with the ground terminal. Consequently, an impedance matching circuit is provided with a parallel inductance L , so that an antenna achieves an improved gain without any loss or deterioration caused by impedance mismatching. On the other hand, the feed line 13 is wound up in the feed line storage compartment 14 as the antenna element 3 is retracted for storage. The antenna element 3 in a stored state, keeping a fixed distance from ground of the radio circuit 4, acts as a coaxial strip line. When the connection terminal 3a at the lower end of the antenna element 3 hits the stopper 15 at a fixed position in a stored state, the connection terminal 3b at the upper end of the antenna element is brought into electrical contact with the connection terminal 5. Concurrently, the switch 12, detecting mechanically or electrically the motion of the antenna element, comes into contact with an open terminal via the coil 11. Consequently, the coil 11 acts as a fixed helical antenna having an open upper end with the antenna element 3 in a stored state. Hence, a high gain antenna with an optimal impedance matching can be achieved without a matching circuit, and therefore causing no matching circuit-related loss. Fig. 7 is a flowchart of an operation of the antenna equipment. Referring to Fig. 7, there are respectively two choices of formations, a matching circuit formation S10 and a helical antenna formation S20, based on the motion of the antenna element 3 in step S1. When the antenna element 3 is pulled out in the step S1, the matching circuit formation S10 is selected and operation proceeds to step S11. The connection terminal 3a at the lower end of the antenna element is brought into contact with the coil 11 via the terminal 5 in the step S11 and the switch 12 comes into contact with a ground terminal in step S12. This completes the matching circuit formation with the antenna element 3 in an extended state. When the antenna element 3 is in a stored state in the step S1, the helical antenna formation S20 is selected and operation proceeds to step S21. The connection terminal 3b at the upper end of the antenna element 3 is brought into contact with the coil 11 via the terminal 5 in the step S21 and the switch 12 comes into contact with an open terminal in a step S22. This completes the helical antenna formation with the antenna element 3 in a stored state. According to this embodiment, the coil 11 acts as a helical antenna with the antenna element 3 in a stored state. This requires no matching circuit to achieve an optimal impedance matching with the antenna element (3) providing a high gain antenna causing no matching circuit-related loss. Embodiment 2. Figs. 8 and 9 illustrate a stopper 17 provided outside the case 2 as a possible alternative of the stopper 15 of the first embodiment provided inside the case 2. The stopper 17 incorporates the connection terminal 5 within itself, whereby the connection terminal 5 is brought into contact with the connection terminal 3a at the lower end of the antenna element 3 without possible failure. According to this embodiment, the absence of the stopper 15 will allow the feed line 13 to move smoothly in and out of the feed line storage compartment 14 with the antenna element 3 as it is extended and retracted. Embodiment 3. Figs. 10 through 11C illustrate a strip line 26 as a feed line as a possible replacement for the coaxial feed line 13. The strip line 26 has a dielectric (DE) substance inbetween a HOT (conductor) of a signal line and a GND (conductor). The feed line storage compartment 14 is provided with a special device to assign a predetermined impedance to the feed line 26 in a stored state. A thinner line can be provided for the feed line 26 than that of the coaxial feed line 13. This allows the feed line storage compartment 14 or the case 2 to be made smaller in breadth providing downsizing of the portable communication equipment. Fig. 12 illustrates a feed line 26a as a possible replacement for the feed line 26. Fig. 13 illustrates a feed line 26b as a possible replacement for the feed line 26. The feed line 26b has two ground GND conductors connected together by way of through holes TH. A plurality of ground GND conductors connected together, as this example shows, by way of through holes TH effectively improves the ground function. Embodiment 4. Figs. 14A through 14C illustrate a triplet feed line 27 as a possible replacement for the coaxial feed line 13. The triplet line has a HOT conductor buried in a the center of the dielectric (DE) substance with a GND conductor on the both sides. A thinner line can be provided for the feed line 27 than that of the coaxial feed line 13. This allows the feed line storage compartment 14 or the case 2 to be made smaller in breadth thereby providing downsizing of the portable communication equipment. Embodiment 5. Figs. 15A through 15C illustrate a Lecher feed line 28 as a possible replacement for the coaxial feed line 13. The Lecher line has a HOT conductor and GND conductor on the same side of a dielectric (DE) substance. A thinner line can be provided for the feed line 28 than that of the feed lines 13, 26 and 27. This allows the feed line storage compartment 14 or the case 2 to be made smaller in breadth thereby providing downsizing of the portable communication equipment. Figs. 16A through 16C illustrate a twin wire feed line 28a as another possible replacement for the coaxial feed line 13. The twin wire feed line 28a is provided with two parallel lines of a HOT conductor on one side and a GND conductor on the other side of a dielectric (DE) substance. Embodiment 6. Figs. 17 and 18 illustrate a coaxial line as a possible replacement for the coaxial strip line discussed in the first embodiment. The antenna element 3 can be a coaxial strip line in a stored state with a fixed distance kept from the radio circuit 4 in the first embodiment. In this embodiment, however, the antenna element 3 can be a coaxial line with a circular metal cylinder 31 for grounding provided around the antenna element in a stored state. The circular metal cylinder 31 is brought into contact with a metallic outer shield (ground GND) of the radio circuit 4 in a stored state of the antenna element 3. Consequently, the circular metal cylinder 31 becomes an outer conductor GND of the coaxial line. The antenna element 3 works as an inner conductor. The coaxial line replaced for the strip line of the first embodiment can reduce leakage loss, which can provide a high gain antenna with the antenna element 3 in a stored state. Embodiment 7. Figs. 19 and 20 illustrate another coaxial line as a possible replacement for the coaxial strip line discussed in the first embodiment. The antenna element 3 can be a coaxial strip line in a stored state with a fixed distance kept from the radio circuit 4 in the first embodiment. In this embodiment, however, the antenna element 3 can be a coaxial line with a rectangular metal cylinder 32 for grounding provided around the antenna element 3 in a stored state. The rectangular metal cylinder 32 is brought into contact with a metallic outer shield (ground GND) of the radio circuit 4 in a stored state of the antenna element 3. Consequently, the circular metal cylinder 31 becomes an outer conductor [GND] of the coaxial line. The antenna element 3 works as an inner conductor. The seventh embodiment effects the same performance as that of the sixth embodiment. The outside diameter of the antenna element 3 is selected based on an optimal impedance. A single type of metal in thickness can be used commonly for producing the rectangular metal cylinder 32 and the radio circuit 4. An antenna equipment of this embodiment can be provided at a lower cost than that of the fifth embodiment. Embodiment 8. Referring to the first embodiment, the coil 11 is used as a matching circuit in an extended state of the antenna element 3 as well as an active antenna element in a stored state. Figs. 21 and 22 illustrate a meander board 29 as a possible replacement for the coil 11. The meander board 29 has a pattern L (inductance L ) mounted on a board. The meander board 29 can provide an improved etching of the conductor pattern L on the board resulting in less variation of inductance L than the coil. This can provide a high gain antenna, and improve the Voltage Standing Wave Ratio VSWR. Embodiment 9. Referring to the first embodiment, the coil 11 is used as a matching circuit in an extended state of the antenna element 3 as well as an active antenna element in a stored state. Figs. 23 and 24 illustrate a commercial chip L 41 as a possible replacement for the coil 11. The chip L 41 is a chip inductor provided for SMD (surface-mounted device) electronic parts. The chip L is developed by a joint technology of a ferritic material art and a greensheet multi-layer wiring art. The chip L , unlike a conventional coil winding inductor, is a ferritic product formed into a greensheet based on highly reliable advanced technologies. The ferritic greensheet type material has a conductor of small sheet resistance printed on it. A layer of the conductor printed greensheet type ferritic materials is united into a multilayer entity by a bias-hole technique and fired for finishing. According to this embodiment, the antenna equipment employing the commercial chip L 41 can be provided smaller in size and provided at a lower cost. Embodiment 10. Figs. 25 through 27 illustrate a connection terminal 103a at the lower end of the antenna element 103 as a possible replacement for the connection terminal 3a. The connection terminal 3a at the lower end of the antenna element is made all of metal in the first embodiment. The connection terminal 103a of this embodiment, however, has an insulator 103e in the center between two metal contacts. A metal contact 103g at a lower end of the connection terminal 103a is connected to a shield 103i of a feed line 113 by soldering. An L shaped sheet metal 18 touching the radio circuit 4 is adhered at the bottom part of the stopper 16. Consequently, the metal contact 103g is brought into contact with a ground of the radio circuit 4 when it touches the L shaped sheet metal 18. Thus, an unstable electric factor with a shield is removed at the upper end of the feed line 113 by shorting. This can improve the electrical performance of the antenna element 103 in an extended state. A connection terminal 103b at the upper end of the antenna element is designed in size to avoid a short in contact with the L shaped sheet metal 18 with the antenna element 103 in a stored state. Referring to the first embodiment, the coaxial feed line 13 is open edged. In this case, there is possible radiation from the feed line 13 when an electric potential difference occurs between the feed line and the metallic outer shield of the radio circuit 4 in an extended state of the antenna element 3. The antenna element 3 also radiates. This may result in poor gain performance with the antenna element in an extended state. According to this embodiment, on the other hand, the open edged shield 103i of the feed line (a coaxial line) 113 is soldered with the metal contact 103g of the connection terminal 103a at the lower end of the antenna element 103. The connection terminal 103a at the lower end of the antenna element 103 in an extended state is brought into contact with the L shaped sheet metal 18 touching the radio circuit 4. A shield contact 103i of the open edged feed line 113 and the outer metal of the radio circuit 4 gives an equipotential environment of electric difference. This results in no unwanted radiation from the coaxial line 113 providing a high gain antenna with the antenna element 103 in an extended state. According to this embodiment, the shield of the connection terminal of the feed line 113 connected to the connecting terminal 103a at the lower end of the antenna element 103 is brought to a forced short in an extended state of the antenna element 103. This can eliminate unwanted radiation and reduce loss caused by feed line insertion or feed line insertion loss providing a high gain antenna. Embodiment 11. A chip element 51 (chip L or/and chip C ) illustrated in Figs. 28 and 29 can be used for fine tuning the impedance matching of the coil 11 as a matching element in an extended state of the antenna element 3 discussed in the first embodiment. The chip C (condensor) 51 has a large capacitance based on an advanced thin film technology of ceramic dielectric layer and a multilayer monolithic technology. The chip C is strong in static and mechanical characteristics because of the solid monolithic structure. Because of its precise designing in dimensions, the chip C is efficient in handling in an automated mounting process. Because its composition materials are only of ceramic and metal, the chip C is efficient in a heat-resistant stable quality and rarely deteriorates in any temperature environment. Because of the characteristic of the monolithic structure and the composition materials, the chip is environmentally highly reliable. Because of the reversible structure and nonpolar nature, the mounting process of the chip can be simplified. Because of its lead wireless structure with a small stray capacitor, the chip can be provided with an ideal circuit design based on theoretical values. Consequently, an antenna can be provided with little residual inductance and an improved frequency characteristic. The chip element 51 can be employed to correct any possible variation of inductance of the coil 11 affected by the outside metal shield (ground GND) of the radio circuit 4. Variation of inductance of the coil 11 can cause an inductance mismatching in an extended state of the antenna element 3 leading to a deteriorated Voltage Standing Wave Ratio VSWR and an increase in reflection loss. The chip element 51 can improve a Voltage Standing Wave Ratio VSWR and reduce reflection loss providing a high gain antenna. Embodiment 12. Referring to the first embodiment, an open ended shield at the connection is used with the coaxial feed line 13 connected to the connection terminal 3a at the lower end of the antenna element. Figs. 30 and 31 illustrate a feed line provided with a λ/4 choke line 61. λ is the wavelength of a signal transmitted by the antenna. The λ/4 choke line 61 shorts the open ended shield and improves the electric performance of the antenna element 3. Embodiment 13. Figs. 32 and 33 illustrate a λ/4 choke strip line 33 as a feed line as a possible replacement for the λ/4 choke coaxial feed line discussed in the twelfth embodiment. The λ/4 choke strip line 33 includes λ/4 choke lines 33x and through holes TH. The λ/4 choke lines 33x reach a GND via the through holes TH. The λ/4 choke strip line 33 works as a sleeve antenna with the antenna element of a λ/4 in length and effects the same performance as that of the twelfth embodiment. Figs. 32 and 33 illustrate the λ/4 choke strip line 33 with the λ/4 choke lines 33x. The λ/4 choke lines 33x can help to short an open ended shield of the feed line 33 connected to the connection terminal 3a at the lower end of the antenna element 3. This results in preventing unwanted radiation from the λ/4 choke strip line 33 leading to the improved electrical performance of the antenna element 3. Thus, the λ/4 choke lines 33x are provided for shorting the open ended shield of the feed line with the antenna element 3 in an extended state. This can eliminate unwanted radiation and reduce feed line insertion loss providing a high gain antenna. Embodiment 14. Figs. 34 and 35 illustrate a λ/4 choke triplet line 34 as a feed line as a possible replacement for the λ/4 choke coaxial feed line connected to the connection terminal 3a discussed in the twelfth embodiment. The λ/4 choke triplet line 34 includes λ/4 choke lines 34x and through holes TH-A and TH-B. The λ/4 choke triplet line 34 effects the same performance as that of the twelfth embodiment. The λ/4 choke lines 34x reach a GND on via the through holes TH-A. The through holes TH-B connect grounds GND on the both sides, which provides an efficient ground function. Figs. 34 and 35 illustrate the λ/4 choke triplet line 34 with the λ/4 choke lines 34x. The λ/4 choke lines 34x can help to short an open ended shield of the feed line 34 connected to the connection terminal 3a at the lower end of the antenna element. This results in preventing unwanted radiation from the λ/4 choke triplet line 34 providing improved electric performance of the antenna element 3. Fig. 36 illustrates a λ/4 choke feed line 34a as a possible replacement for the previous feed lines. The λ/4 choke feed line 34a includes λ/4 choke feed lines 34y and through holes TH-A and TH-B. Referring to the figure, the λ/4 choke lines 34y reach a GND via the through holes TH-A. The through holes TH-B connect two grounds GND on the both sides. Figs. 37 and 38 illustrate other possible replacements for the previous feed lines. Fig. 37 shows a λ/4 choke feed line 34b with λ/4 choke lines 34y. Fig. 38 shows a λ/4 choke feed line 34c with λ/4 choke lines 34z. Thus, the λ/4 choke lines 34x, 34y and 34z are provided for shorting the open ended shield of the feed line with the antenna element in an extended state. This can eliminate unwanted radiation and reduce feed line insertion loss providing a high gain antenna. Embodiment 15. Figs. 39, 40 and 41 illustrate a λ/4 choke twin wire feed line 35 as a possible replacement for the λ/4 choke coaxial feed line discussed in the twelfth embodiment. The λ/4 choke twin wire feed line 35 effects the same performance as that of the twelfth embodiment. Figs. 39, 40 and 41 illustrate the λ/4 choke twin wire feed line 35 with λ/4 choke lines. The λ/4 choke lines can help to short an open ended shield of the feed line 35 connected to the connection terminal 3a at the lower end of the antenna element. This results in preventing unwanted radiation from the λ/4 choke twin wire feed line 35 leading to improved electric performance of the antenna element 3. Thus, the λ/4 choke lines are provided for shorting the open ended shield of the feed line 35 with the antenna element in an extended state. This can eliminate unwanted radiation and reduce feed line insertion loss providing a high gain antenna. Figs. 42, 43 and 44 illustrate a λ/4 choke Lecher line 35a as a feed line as a possible replacement for the previous feed lines. Embodiment 16. Figs. 45 and 46 illustrate a line element 42 as a possible replacement for the coil 11 discussed in the first embodiment. The coil 11 works as a matching element with the antenna element in an extended state and as an active antenna element in a stored state. On the other hand, the line element 42 can work as a reverse L shaped line antenna with the antenna element 3 in a stored state. According to this embodiment, the line element 42 can be used with the antenna element 3 as a matching element in an extended state and as a reverse L shaped line antenna in a stored state. Consequently, the antenna equipment can be provided at a lower cost with a small and light body in size and weight. Embodiment 17. Figs. 47 and 48 illustrate a pattern L 52 on a board for fine tuning the impedance matching with the antenna element in an extended state as a possible replacement for the coil 11 as a matching element discussed in the first embodiment. The pattern L 52 can be applied to the eleventh embodiment if there is a limitation on the size of the coil. The pattern L 52 can realize antenna equipment with a thinner and smaller body. Embodiment 18. Figs. 49 and 50 illustrate a board element 43 as a possible replacement for the coil 11 discussed in the first embodiment. The board element 43 works as a reverse L shaped board antenna with the antenna element 3 in a stored state. The board element 43 can achieve the same effect as that of the sixteenth embodiment. The board element can perform better than the line element in terms of bandwidth of the Voltage Standing Wave Ratio VSWR characteristic.

Claims: Antenna equipment comprising: a case (2) containing a radio circuit (4); a first antenna element (3, 103), connected to the radio circuit (4), which is movable between a stored position within the case (2) and an extended position outside of the case (2); and means (11) acting as a second antenna element when the first antenna element (3, 103) is in the stored position, characterised in that said acting means (11) are connected via a first terminal (5) to the first antenna element (3, 103) and act as a matching circuit element when the first antenna element (3, 103) is in the extended position, wherein the acting means (11) includes a second terminal connected to a switch (12) which couples the second terminal to a ground terminal when the first antenna element (3, 103) is in the extended position and which couples the second terminal to an open circuit when the first antenna element (3, 103) is in the stored position. The equipment of Claim 1, wherein the acting means (11) is provided outside of the case (2). The equipment of Claim 1 or 2, wherein the acting means (11) is coupled via said first terminal (5) to one end (3b) of the first antenna element (3, 103) when the first antenna element (3, 103) is in the stored position, and is coupled to a second end (3a) of the first antenna element (3, 103) when the first antenna element (3, 103) is in the extended position. The equipment of any of Claims 1 to 3, further comprising a stopper (17) incorporating therein the first terminal, the stopper (17) positioning the first antenna element (3, 103) with respect to the case (2) and coupling the first terminal to one of the ends of the first antenna element (3, 103). The equipment of any of Claims 1 to 4, further comprising a signal line (13, 113) connected between the first antenna element (3, 103) and the radio circuit (4). The equipment of Claim 5, wherein the signal line (13, 113) is selected from the group comprising a coaxial strip line (13), a coaxial line (13), a strip line (26, 26a, 26b), a triplet line (27), a Lecher line (28), and a coaxial line (13) having a predefined shaped shield. The equipment of any of Claims 1 to 6, wherein the acting means (11) is selected from the group comprising a coil (11), a meander board (29), a chip (41, 51), a line element (61, 52) a reverse L shaped line antenna (42) and a reverse L shaped board antenna (43). The equipment of any one of Claims 1 to 7, further comprising a signal line (13, 113) having first and second ends, a hot conductor (HOT) and a ground conductor (GND), the signal line (13, 113) being connected at the first end thereof to the first antenna element (3, 103) and being connected at the second end thereof to the radio circuit (4); wherein the ground conductor (GND) is coupled at the first end to a ground terminal of the radio circuit (4). The equipment of Claim 8, wherein the second end of the signal line (33, 34, 35) includes a λ/4 choke, λ being a wavelength of a signal on the signal line (33). The equipment of any of Claims 1 to 9, further comprising an adjustment device (51) acting as a matching element, inserted between the second terminal and ground. The equipment of Claim 10, wherein the adjustment device (51) is selected from the group of an integrated circuit and a circuit board. A method of communication using antenna equipment including first and second antenna elements (3, 103; 11) coupled to a radio circuit (4), comprising the steps of: extending the first antenna element (3, 103) to an extended position for a first communication condition; providing the second antenna element (11) as a matching circuit for the first antenna element (3, 103) in the extended position by connecting one end of the second antenna element (11) to a first end of the first antenna element (3, 103) and connecting a second end of the second antenna element (3, 103) via a switch (12) to a ground; retracting the first antenna element (3, 103) to a stored position for a second communication condition; and providing the second antenna element (11) as an antenna when the first antenna element (3, 103) is in the stored position by connecting the one end of the second antenna element (11) to a second end of the first antenna element (3, 103) and connecting the second end of the second antenna element (11) via said switch (12) to an open circuit. The communication method of Claim 12, further comprising the step of providing a signal line (13) for the second antenna element (11) with the first antenna element (3, 103). The communication method of Claim 12 or 13, wherein the second antenna element (11) is selected from the group comprising a helical antenna (11) and a reverse L-shaped antenna (43).

Inventors: IMANISHI YASUHITO, IMANISHI, YASUHITO, IMANISHI, YASUHITO, C/O MITSUBISHI DENKI K.K. TSUS
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1995
Main classification: H01Q1
IPC codes: H01Q1, H04B1