Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1999-09-02
2001-02-13
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S846000
Reexamination Certificate
active
06188360
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radio-frequency radiation source, radio-frequency radiation source array, antenna module, and radio equipment to be used in radio-frequency bands of a millimeter wave region, and so on.
2. Description of the Related Art
In a radio-frequency antenna, when a circuit to turn on and off an electromagnetic wave to be output from the radiation source is constructed, heretofore a switch is provided between an element or a conductor pattern to be used as a radiation source and a feed system. The example is shown in FIG.
15
.
FIG. 15A
is an equivalent circuit diagram and
FIG. 15B
is a perspective view showing the construction of a radio-frequency circuit portion. In this way, a diode D
1
is provided in series to a feed circuit of a square patch antenna, and a series circuit of a diode D
2
and a resistor R is provided between the feed circuit and ground.
The above circuit constitutes a so-called SPST (Single Pole Single Throw) radio-frequency switch and is to switch on and off radiation of an electromagnetic wave by switching on and off the power to the radiation source.
In such a system, because the loss in the switch(diode) is great, there is a problem in that the antenna gain and efficiency are reduced and the antenna noise is increased. Further, because the radiation source and the switch are constructed using different circuits, there is a problem in that the circuits'construction becomes complicated. For example, as shown in
FIG. 15
, when the power is not supplied to the radiation source, the resistor R is provided so that the impedance looking at the side of the radiation source from the input terminal is constant, and accordingly a circuit construction in which power is consumed at the resistor is required. Therefore, at least two diodes are required, and a circuit (DC biasing circuit) applying controlling voltages to these diodes becomes complicated.
FIG. 16
shows an example. In the figure, C
1
, C
2
, and C
3
are capacitors to block DC currents, and L
1
, L
2
, and L
3
acts as a choke to radio frequencies and are inductors to supply DC biasing voltages to diodes D
1
and D
2
.
SUMMARY OF THE INVENTION
According to the present invention, a radio-frequency radiation source in which the loss in the switch is greatly reduced, the complication of the circuit construction is solved, and the electromagnetic radiation can be switched on and off, and a radio-frequency radiation source array, antenna module, and radio equipment using such are provided.
In order to solve the above problems, in the present invention, a radio-frequency radiation source comprises a switching element or a variable reactance element, a resonator in which a resonance frequency is changed by turning on or off the switching element or by switching the reactance of the variable reactance element, a radiation means to radiate to the outside an electromagnetic energy of a fixed frequency stored in the resonator, and a transmission line coupled to the resonator.
In this way, the resonance frequency of the resonator is changed by turning on and off the switching element or by switching the reactance of the variable reactance element. When the frequency of a signal to be supplied to the resonator through the transmission line coincides with the resonance frequency of the resonator, the electromagnetic field is confined in the resonator and radiated as an electromagnetic wave to the outside, but when the resonance frequency of the resonator does not coincide with the frequency of the signal supplied through the transmission line, the resonator does not resonate and an electromagnetic wave is not radiated. In like manner, when the resonance frequency of the resonator coincides with the frequency of an electromagnetic wave incident from the outside, the electromagnetic field is confined in the resonator and the reception signal is radiated, and when the resonance frequency of the resonator does not coincide with the frequency of the electromagnetic wave incident from the outside, the resonator doe not resonate and the signal is not transmitted through the transmission line.
Thus, a radiation source and switch are not constructed as separate circuits, but a switching function is included in the radiation source itself. Because of this, a loss in the switch is not caused. That is, in a condition in which the resonator does not resonate, it is as if there was no resonator itself and the loss becomes almost zero. Further, even if the resonator resonates, because any loss but the loss caused by the Q of the resonator itself is not brought about, a low-loss radiation loss can be realized. Further, because the switch and radiation source are not required to be made separate circuits, the circuit construction is greatly simplified. Particularly, it is not required to provide any switching element and biasing circuit to the switching element on the feed line, and the total circuit construction is greatly simplified.
In the present invention, the resonator comprises electrodes having opposing electrodeless parts formed on both surfaces of a dielectric plate, a slit formed in a section of the electrodeless part at least on one surface of the dielectric plate, and the switching element or the variable reactance element provided across the slit. As constructed this way, because the electrodeless parts act as a dielectric resonator and the electromagnetic field distribution in the slit portion of the electrodeless parts is changed by turning on and off the switching element or by switching the reactance of the variable reactance element, in accordance with the change the resonance frequency can be largely changed.
Further, in the present invention, a dielectric resonator is placed and held in an electrodeless part on the dielectric plate. As constructed this way, even if the dielectric constant of the dielectric plate is relatively high, the radiation efficiency of an electromagnetic wave can be increased.
Further, in the present invention, a secondary line different from a transmission line to be coupled to the resonator is provided, and the switching element or the variable reactance element is connected to the secondary line. As constructed this way, the resonance frequency of the resonator can be changed by turning on and off the switching element or by switching the reactance of the variable reactance element.
Further, in the present invention, a radio-frequency radiation array comprises a plurality of the radio-frequency radiation sources, wherein one end of the transmission lines of these radio-frequency radiation sources is connected in parallel with each other. Further, a radio-frequency radiation array comprises the connected-in-series transmission lines of the radio-frequency radiation sources, one end portion of which is terminated. As constructed this way, the radio-frequency radiation array can be used as an array antenna having a transmission line and a plurality of radiation sources.
Further, in the present invention, an antenna module comprises a dielectric lens in which the location of each of the radio-frequency radiation sources of the above radio-frequency radiation source array constitutes nearly a focusing surface. According to this construction, by making a plurality of radio-frequency radiation sources selectively activated, the direction of a beam to be determined by the relative positional relationship between the radio-frequency radiation sources and the dielectric lens can be changed.
Further, in the present invention, a radio equipment comprises a transmission circuit or reception circuit connected to a transmission line of the radio-frequency radiation source, radio-frequency radiation source array, or antenna module.
REFERENCES:
patent: 3680135 (1972-07-01), Boyer
patent: 5105200 (1992-04-01), Koepf
patent: 5202697 (1993-04-01), Bonebright et al.
patent: 5532705 (1996-07-01), Hama
patent: 5801660 (1998-09-01), Ohtsuka et al.
Iio Ken'ichi
Ishikawa Yohei
Kato Takatoshi
Sakamoto Koichi
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Tran Chuc D
Wong Don
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