Communications: radio wave antennas – Antennas – Loop type
Reexamination Certificate
2000-08-23
2002-12-31
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
Loop type
C343S742000, C343S795000
Reexamination Certificate
active
06501436
ABSTRACT:
TECHNICAL FIELD
The present invention is related to an antenna apparatus, and a radio apparatus and a radio relaying apparatus using this antenna apparatus in a mobile communication system mainly known as the PHS (Personal Handyphone System) system.
TECHNICAL BACKGROUND
Conventionally, in an outdoor type small-sized base station apparatus (master unit) conducted in a mobile communication system such as the PHS system, while an omunidirectional antenna such as a sleeve antenna is used, the antenna gain of this omunidirectional antenna is lower than or equal to about 2 dBi. Also, in a fixed terminal apparatus used in a local wireless network (wireless local loop: WLL) which utilizes a mobile communication system such as the PHS system, an antenna gain requires approximately 10 dBi.
Very recently, in the above-described mobile communication system, high gains are required for antennas so as to extend communication covering areas. These antennas are used in indoor type compact base station apparatuses (mother units) and fixed terminal apparatuses.
As frequencies of the above-explained mobile communication system, 1,900 MHz band and 800 MHz band are mainly used. As antennas having high gains operable in these frequency bands, multi-staged co-linear array antennas are known from, for instance, Japanese Patent Publications Hei-5-267932, Hei-9-232851, and Hei-8-139521. This sort of antenna is to secure such a high gain by that while antennas having omnidirectional directivity characteristics within horizontal planes are arranged in the multi-stage manner along the vertical direction, the directivity characteristics within the vertical planes are narrowed by vertical polarized waves.
Also, for instance, as disclosed in Japanese Patent Publications Hei-5-259733 and Hei-8-204433, end-fire array antennas are known, namely typically known as a YAGI antenna and a dipole antenna equipped with a reflection plate. This sort of antenna is to secure a high gain by that non-powered elements are arranged along a direction parallel to a major radiation direction.
Furthermore, for example, as disclosed in Japanese Patent Publication Hei-6-334434, a broad-side array antenna is known, namely typically known as a patch array antenna. This sort of antenna is to secure a high gain by that while a plurality of antennas are arranged within a plane located perpendicular to a major radiation direction, these plural antennas are energized by the distribution manner.
Also, for instance, as described in Japanese Patent Publication Hei-6-268432 and also Japanese Utility Model Publication Hei-6-44219, a slim type antenna is known, namely typically known as a loop antenna equipped with a reflection plate and a slot antenna.
Then, as a broad-side array antenna mainly utilized in the VHF frequency range, for instance, “ANTENNA HANDBOOK” issued by “CQ Publishing Co.”, on page 366, discloses such an antenna that two 1-wavelength antennas are arranged in either a regular square or a circle. Then, it is known in the field that a diamond-shaped antenna to which this broad-side array antenna has been applied can obtain a gain of approximately 6 dBi in the 1,900 MHz band and the 800 MHz band, and further, this diamond-shaped antenna having a compact/simple structure can obtain a gain of approximately 10 dBi in combination with a reflection plate.
Also, such an antenna is known in the field, in which plural sets of the above-described diamond-shaped antennas are arranged in a parallel connection manner or a series connection manner.
FIG. 3
is a diagram for representing the conventional antenna apparatus structure and the current distribution thereof, in which 6 sets of diamond-shaped antennas are connected to each other in the parallel manner. This antenna apparatus is so arranged that 6 pieces of the diamond-shaped antennas
14
to
19
are connected in the parallel manner, and the power supply unit
20
is connected to the center portion. While the length “a” of one edge of the diamond shape is set to a ½ wavelength (&lgr;/2), these diamond-shaped antennas
14
to
19
are operated as the broad-side array antenna constituted by 4 sets of half wavelength antennas so as to radiate the vertical polarized waves along the X direction and the −X direction. For instance, in the case that the operation frequency of the antenna apparatus is set to 1,900 MHz, the length “a” of one edge of the diamond shape becomes 79 mm. Also, the entire width of the antenna apparatus becomes 670 mm. In this case, in the antenna apparatus shown in
FIG. 3
, in particular, the current distribution of the diamond-shaped antennas
16
to
19
located near the center cannot be optimized by mutually coupling the respective diamond-shaped antennas. As a result, it is known in this field that the effect of the plural arrangement becomes relatively small, a single set of the diamond-shaped antenna owns the gain of approximately 11.5 dBi, and the gain of approximately 15.5 dBi is obtained by combining the diamond-shaped antenna with the reflection plate.
Also, for example, Japanese Patent Publications Hei-6-188623 and Hei-6-169216, and Japanese Utility Model Publication Hei-4-44713 describe such a dual-loop antenna that a plurality of 1-wavelength loop antennas are connected parallel to each other, or series to each other.
FIG. 4
represents the conventionally known structure of dual-loop antenna. This dual-loop antenna is arranged in such a manner that two sets of the 1-wavelength loop antennas are connected parallel to each other via the ½-wavelength transfer path, and the power supply unit is connected to the central portion. Both the 1-wavelength loop antenna
21
and the 1-wavelength loop antenna
22
are operated in such a way that the vertical polarized waves are radiated along the X direction and the −X direction. While the length of the transfer path
23
is set to a ¼ wavelength and the length of the transfer path
24
is set to a ¼ wavelength,both the 1-wavelength loop antenna
21
and the 1-wavelength loop antenna
22
are connected to each other, and the power supply unit
25
is connected to the center point thereof. Since the dual-loop antenna is arranged in this manner, two sets of the 1-wavelength loop antennas
21
and
22
can be excited under in-phase condition. It is known in the field that a single set of the 1-wavelength loop antenna owns the gain of approximately 8 dBi, and the two 1-wavelength loop antennas own the gain of approximately 12 dBi by being combined with the reflection plate.
On the other hand, as a radio relaying apparatus used in the above-explained mobile communication system, the following radio relaying apparatuses are known in the field. That is, for instance, Japanese Patent Publication Hei-8-8807 discloses such a radio relaying apparatus which employs the antenna commonly-using filter and a large number of narrow-band amplifiers. Japanese Patent Publication Hei-8-508377 discloses such a radio relaying apparatus which uses the amplifier and the switch operable in synchronism with the upstream time instant and the downstream time instant in the time division duplexing (TDD) system. Also, Japanese Patent Publication Hei-8-298485 describes such a radio relaying apparatus in which the two relaying systems constructed of the upstream/downstream relaying systems are provided in the time division duplexing system.
However, in order to secure the high gain in the above-explained conventional multi-stage co-linear array antenna, a large number of antennas must be arrayed in the multi-stage manner along the vertical direction. For example, in the case that the gain of 10 dB is obtained in the 1,900 MHz band, the antenna height of 1 meter would be required. As a result, there are problems in the antenna setting places and also the mechanical strengths of the antennas. Also, it is not proper manner to build such a high-height antenna in the radio apparatus.
Also, in order to secure the high gain in the above-described conventional end-fire array antenna, a large number of antennas m
Haruki Hiroshi
Saito Yutaka
Matsushita Electric - Industrial Co., Ltd.
Pearne & Gordon LLP
Phan Tho
LandOfFree
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