Description of Related Art A repeater and cellular phone antenna for a mobile communication service is directed to receiving a radio signal which is generated in a base station or in an external place and externally transmitting an electric signal generated in a communication instrument.

In the type of an antenna for cellular phone, an extendable antenna is generally used due to an inherent structural characteristic of a cellular phone and its antenna. The above cellular phone has a problem for implementing a small size and lightness body of a cellular phone. Therefore, it is impossible to implement a small sized antenna in consideration of a decrease in performance.

In order to overcome the above problems, the applicant of the present

invention has the Korean patent No. 1994-0011486. According to the above patent'486, the slant folded monopole antenna is capable of enhancing a receiving gain by increasing an impedance even when the length of the antenna is shortened.

The above conventional antenna will be described in detail with reference to the accompanying drawings.

Figure 1 is a perspective view of a conventional slant folded monopole antenna. As shown therein, the slant folded monopole antenna 101 includes a support plate 111 having a connector for a connection with a cellular phone, a receiver 120 which is vertically installed in an upper portion of the support plate 111, and a sub-receiving portion 130 which is bent from an upper portion of the receiver 120 and downwardly slanted in a direction of the support plate 111 and grounded to a narrow portion 151 of the support plate 111.

In addition, the receiver 120 has a length shorter than the length of an antenna, and a lower portion of the receiver 120 is coated with a coating material. In the interior of the coated material, there are provided an outer conductive material (not shown) for supporting the receiver 120, an empty core coil (not shown) disposed between the receiver 120 and the connector, and an insulation material (not shown) disposed between the outer conductive material and the empty coil.

In the thusly constructed conventional art, it is possible to implement a small sized cellular phone by decreasing the length of the antenna. However, since an end portion of the sub-receiver 130 is grounded with the narrow potion 151, it is impossible to use in a wider frequency band due to a non-resonance characteristic. In addition, there is a limit for enhancing an impedance and gain.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a folded monopole antenna for a cellular phone which overcomes the problems encountered in the conventional art.

It is another object of the present invention to provide a folded monopole antenna for a cellular phone which is capable of decreasing the length of an antenna of a cellular phone and is adapted in a wider frequency band and is capable of enhancing an impedance and gain.

To achieve the above objects, in a folded monopole antenna which has a support portion 10 having a connector 13 connected with a cellular phone 3 in a lower portion of the same, a receiver 20 which is vertically provided in an upper portion of the support portion 10 and is connected with the connector 13, and a sub-receiver 30 which is downwardly bent from an upper portion of the receiver 20, there is provided a folded monopole antenna for a cellular phone in

which an end portion 31 of the sub-receiver 30 is distanced from an end line 11 of an upper portion of the cellular phone by a certain distance for thereby obtaining a certain resonance interval"a", so that it is possible to enhance an impedance and gain by increasing a transmission and receiving band.

The sub-receiver 30 is bent in a horizontal direction from at least one portion of the receiver 20 and is vertically downwardly bent in parallel with the receiver 20. The sub-receiver 30 is bent in a horizontal direction from at least one portion of the receiver 20 and is downwardly bent for thereby having a certain slant angle with respect to the receiver 20.

The sub-receiver 30 is bent in a horizontal direction from at least one portion of the receiver 20 and is bent in an inward direction at an angle of 90° by multiple times.

The sub-receiver 30 is downwardly bent from a plurality of portions of the receiver for thereby forming a plurality of downwardly bent sub-receivers.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become better understood with reference to the accompanying drawings which are given only by way of illustration and thus are not limitative of the present invention, wherein; Figure 1 is a perspective view illustrating a conventional slant folded

monopole antenna; Figure 2 is a perspective view illustrating a folded monopole antenna for a cellular phone according to a first embodiment of the present invention; Figure 3 is a partial cross sectional view of a portion A of Figure 2 according to the present invention; Figure 4 is a perspective view illustrating a state of a use of a folded monopole antenna for a cellular phone of Figures 2 and 3; Figure 5 is a view illustrating a result of a measurement of a standing wave of a folded monopole antenna for a cellular phone of Figures 2 and 3; Figure 6 is a view illustrating a result of a measurement of a folded monopole antenna for a cellular phone of Figures 2 and 3; Figure 7 is a perspective view illustrating a folded monopole antenna for a cellular phone according to a second embodiment of the present invention; Figure 8 is a view illustrating a result of a measurement of a characteristic of a standing wave of a folded monopole antenna of a cellular phone of Figure 7; Figure 9 is a perspective view illustrating a folded monopole antenna for a cellular phone according to a third embodiment of the present invention; Figure 10 is a perspective view illustrating a folded monopole antenna for a cellular phone according to a fourth embodiment of the present invention;

Figure 11 is a perspective view illustrating a folded monopole antenna for a cellular phone according to a fifth embodiment of the present invention; and Figure 12 is a perspective view illustrating a folded monopole antenna for a cellular phone according to a sixth embodiment of the present invention.

DETAILED DESCRIPTION OF PREFFERED EMBODIMENTS The preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 2 is a perspective view illustrating a folded monopole antenna for a cellular phone according to a first embodiment of the present invention, and Figure 3 is a partial cross sectional view of a portion A of Figure 2 according to the present invention.

As shown therein, the folded monopole antenna 1 for a cellular phone according to the present invention includes a support portion 10, a receiver 20 which is vertically installed in an upper portion of the support portion 10, and a sub-receiver 30 which is downwardly bent from an upper portion of the receiver 20.

At this time, the support portion 10 is formed of a connector 13 and a urethane coating material 21, and the connector 13 is formed of a narrow and long conductive plate, and one end of the same is flat, and the other end of the

same is bent in a L-shaped or in a semi-circular shape. The lower portion of the receiver 20 is surrounded by the coating material 21 such as urethane.

As shown in the drawings, the connector 13 is formed of a flat portion and a bent portion, and a contact portion 15 is formed in an intermediate portion of the bent portion of the same for thereby being electrically connected with a signal receiving circuit of the cellular phone. When adapting the antenna 1 to the cellular phone 3, the signal received in the antenna 1 through the contact portion 15 is transferred to a signal receiving circuit of the cellular phone 3.

The sub-receiver 30 is horizontally bent from the upper side of the receiver 20 and then is downwardly bent in parallel with the receiver 20. An end portion 31 of the same is distanced from the end line 11 of the upper portion of the cellular phone and has a resonance interval"a"for thereby providing a resonance characteristic to the antenna 1.

As shown in Figure 4, the folded monopole antenna 1 for a cellular phone according to the present invention is directed to transmitting and receiving a signal in a state that the same is engaged to the cellular phone 3.

Since the antenna 1 is folded, the antenna 1 has a current distribution which is two times compared to the conventional antenna which is not folded, so that a radiation resistance characteristic is high, and since the current remains in the sub-receiver 30 of the bent region from the receiver 20, an antenna effective

height is high, and a receiving power is increased, and a gain is increased.

In addition, since the end portion 31 of the sub-receiver 30 is distanced from the end line 11 of the upper portion of the cellular phone and has a resonance interval"a"therebetween, it is possible to increase a capacitance of the antenna 3, and it is possible to use the cellular phone 3 in a wider frequency band by providing a desired resonance characteristic.

Figure 5 is a view illustrating a result of a measurement of a standing wave characteristic of a folded monopole antenna for a cellular phone of Figures 2 and 3 which is measured using a network analyzer. As shown therein, there is shown a good characteristic of below 2: 1 in the PCS frequency band, it is confirmed that it is possible to use the cellular phone in a wider frequency band.

In addition, Figure 6 is a view illustrating a result obtained by measuring a radiation pattern of a folded monopole antenna 1 for a cellular phone of Figures 2 and 3. As shown therein, there is shown a characteristic very similar with that of a conventional helical antenna which has a non-direction oriented characteristic. Therefore, the present invention may be adapted to the antenna 1 for the cellular phone 3.

Figure 7 is a perspective view of a folded monopole antenna for a cellular phone according to a second embodiment of the present invention. As

shown therein, the folded monopole antenna 1 for a cellular phone according to the present invention has the same construction as the first embodiment of the present invention except for the folded monopole antenna 1 and the sub- receiver 30. In this embodiment of the present invention, the sub-receiver 20 is downwardly bent for thereby having a certain slant angle with respect to the receiver 20, and the end portion 31 of the sub-receiver 30 is distanced from the end line 11 of the upper side of the cellular phone by a certain resonance interval"a".

In addition, Figure 8 is a view illustrating a result of a measurement o a standing wave characteristic of a folded monopole antenna of Figure 7. As shown therein, in the monopole antenna 1 for a cellular phone according to the second embodiment of the present invention, since the sub-receiver 30 is slant and bent, so that it is possible to obtain a band characteristic which is better by about 20% compared to the folded monopole antenna 1 for a cellular phone according to the first embodiment of the present invention.

Figures 9 and 10 are perspective views illustrating a folded monopole antenna for a cellular phone according to the third and fourth embodiments of the present invention. As shown therein, in the folded monopole antenna 1 for a cellular phone according to the present invention, there may be provided a plurality of bent structures of the sub-receiver 30 or a plurality of the slant bent

sub-receivers 30 may be provided.

Figures 11 and 12 are perspective views illustrating a Folded monopole antenna for a cellular phone according to the fifth and sixth embodiments of the present invention. As shown therein, the sub-receiver 30 of the folded monopole antenna 1 for a cellular phone according to the present invention is bent in a horizontal direction from at least one region of the receiver 20 and is inwardly bent at an angle of 90° by multiple times. At this time, the receiver 20 and the sub-receiver 30 may be coated with the coating material 21.

The sub-receiver 30 may be fabricated in various shapes in addition to the above described constructions. Various shapes of the antenna 1 having a resonance interval"a"which is formed in such a manner that the end portion 31 of the sub-receiver 30 is distanced from the end line of the upper side of the cellular phone are included in the scope of the present invention.

In the present invention, since the folded antenna for the cellular phone according to the present invention is fabricated in a folded shape, it is possible to implement a small sized product of the cellular phone 3 by decreasing the length of the antenna 1. In addition, a resonance characteristic is implemented based on the resonance interval"a"by forming a resonance interval"a"in the end portion 31 of the sub-receiver 30, it is possible to use the cellular phone 3 according to the present invention in a wider frequency band, and it is possible

to enhance an impedance and gain.

As described above, in the present invention, since a resonance interval is formed by distancing an end portion of the sub-receiver of the antenna from an end line of the upper side of the cellular phone, it is possible to decrease the length of the antenna, and the cellular phone may be used in a wider frequency band, and an impedance and gain are enhanced.

As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described examples are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.