Phased array antenna

Abstract

Provided is a phased array antenna in which a delay time of a radio frequency signal supplied to each antenna element is not dependent on frequency. Each feeding circuit (Fi) of the phased array antenna (1) includes: a time delay element (TDi) configured to impart a time delay ti to a sum signal V.sub.IF+LO(t) which is obtained by adding an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t); a demultiplexer (DPi) configured to demultiplex a resulting delayed sum signal V.sub.IF+LO(tti) so as to provide a delayed intermediate frequency signal V.sub.IF(tti) and a delayed local signal V.sub.LO(tti); and a transmission mixer (TMXi) configured to multiply the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LO(tti) so as to provide a delayed radio frequency signal V.sub.RF(tti), each feeding circuit Fi being configured to supply the delayed radio frequency signal V.sub.RF(tti) to a corresponding antenna element (Ai).

Claims

1. A phased array antenna comprising: n (n is an integer of 2 or more) antenna elements A1, A2, . . . and An; n feeding circuits F1, F2, . . . and Fn; and a multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t), each feeding circuit Fi (i=1, 2, . . . n) including: a time delay element configured to generate a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.IF+LO(t); a demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(tti) and a delayed local signal V.sub.LO(tti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti); and a transmission mixer configured to generate a delayed radio frequency signal V.sub.RF(tti) by multiplying the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LO(tti), each feeding circuit Fi being configured to supply the delayed radio frequency signal V.sub.RF(tti) to a corresponding antenna element Ai, wherein each feeding circuit Fi further includes: a first reception mixer configured to generate a difference frequency signal V.sub.k(t+ti) by multiplying (a) a radio frequency signal V.sub.RF(t+ti) which has been received by use of the corresponding antenna element Ai by (b) a doubled-frequency local signal V.sub.LO2(t), whose frequency is twice that of the local signal V.sub.LO(t); and a second reception mixer configured to generate an intermediate frequency signal V.sub.IF(t+ti) by multiplying the difference frequency signal V.sub.k(t+ti) by the delayed local signal V.sub.LO(tti), and wherein each feeding circuit Fi is configured to supply, to a receiving circuit, a delayed intermediate frequency signal V.sub.IF(t) obtained by imparting the time delay ti to the intermediate frequency signal V.sub.IF(t+ti) by use of the time delay element.

2. A phased array antenna comprising: n (n is an integer of 2 or more) antenna elements A1, A2, . . . and An; n feeding circuits F1, F2, . . . and Fn; and a multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t), each feeding circuit Fi (i=1, 2, . . . n) including: a time delay element configured to generate a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.IF+LO(t); a demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(tti) and a delayed local signal V.sub.LO(tti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti); and a transmission mixer configured to generate a delayed radio frequency signal V.sub.RF(tti) by multiplying the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LO(tti), each feeding circuit Fi being configured to supply the delayed radio frequency signal V.sub.RF(tti) to a corresponding antenna element Ai, wherein each feeding circuit Fi further includes: a first reception mixer configured to generate an intermediate frequency signal V.sub.IF(t+ti) by multiplying (a) a radio frequency signal V.sub.RF(t+ti) which has been received by use of the corresponding antenna element Ai by (b) the delayed local signal V.sub.LO(tti); a reception multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding the intermediate frequency signal V.sub.IF(t+ti) and the delayed local signal V.sub.LO(tti); a reception demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(t+titi) and a doubly delayed local signal V.sub.LO(t2ti) by demultiplexing a sum signal V.sub.IFF+LO(tti), the sum signal V.sub.IFF+LO(tti) being obtained by imparting the time delay ti to the sum signal V.sub.IF+LO(t) by use of the time delay element; and a second reception mixer configured to generate a delayed radio frequency signal V.sub.RF(t) by multiplying the delayed intermediate frequency signal V.sub.IF(t+titi) by the doubly delayed local signal V.sub.LO(t2ti), and wherein each feeding circuit Fi is configured to supply the delayed radio frequency signal V.sub.RF(t) to a receiving circuit.

3. A phased array antenna comprising: n (n is an integer of 2 or more) antenna elements A1, A2, . . . and An; n feeding circuits F1, F2, . . . and Fn; and a multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t), each feeding circuit Fi (i=1, 2, . . . n) including: a time delay element configured to generate a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.IF+LO(t); a demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(tti) and a delayed local signal V.sub.LO(tti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti); and a transmission mixer configured to generate a delayed radio frequency signal V.sub.RF(tti) by multiplying the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LO(tti), each feeding circuit Fi being configured to supply the delayed radio frequency signal V.sub.RF(tti) to a corresponding antenna element Ai, wherein each feeding circuit Fi further includes: a first reception mixer configured to generate an intermediate frequency signal V.sub.IF(t+ti) by multiplying (a) a radio frequency signal V.sub.RF(t+ti) which has been received by use of the corresponding antenna element Ai by (b) the local signal V.sub.LO(t); a reception multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding the intermediate frequency signal V.sub.IF(t+ti) and the local signal V.sub.LO(t); a reception demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(t+titi) and a delayed local signal V.sub.LO(tti) by demultiplexing a delayed sum signal V.sub.IF+LO(tti), the delayed sum signal V.sub.IF+LO(tti) being obtained by imparting the time delay ti to the sum signal V.sub.IF+LO(t) by use of the time delay element; and a second reception mixer configured to generate a delayed radio frequency signal V.sub.RF(t) by multiplying the delayed intermediate frequency signal V.sub.IF(t+titi) by the delayed local signal V.sub.LO(tti), and wherein each feeding circuit Fi is configured to supply the delayed radio frequency signal V.sub.RF(t) to a receiving circuit.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a block diagram illustrating a configuration of a phased array antenna in accordance with Embodiment 1 of the present invention.

(2) FIG. 2 is a block diagram illustrating a configuration of a phased array antenna in accordance with Embodiment 2 of the present invention.

(3) FIG. 3 is a block diagram illustrating a configuration of a phased array antenna in accordance with Embodiment 3 of the present invention.

(4) FIG. 4 is a block diagram illustrating a configuration of a phased array antenna in accordance with Embodiment 4 of the present invention.

(5) FIG. 5 is a block diagram illustrating a configuration of a phased array antenna in accordance with Embodiment 5 of the present invention.

(6) FIG. 6 is a block diagram illustrating a configuration of a phased array antenna in accordance with Embodiment 6 of the present invention.

(7) FIG. 7 is a block diagram illustrating a configuration of a phased array antenna in accordance with Embodiment 7 of the present invention.

(8) FIG. 8 is a block diagram illustrating a configuration of a conventional phased array antenna. (a) of FIG. 8 illustrates a configuration of an RF-controlling phased array antenna. (b) of FIG. 8 illustrates a configuration of an IF-controlling phased array antenna.

DESCRIPTION OF EMBODIMENTS

Embodiment 1

(9) The following description will discuss, with reference to FIG. 1, a phased array antenna 1 in accordance with Embodiment 1 of the present invention. FIG. 1 is a block diagram illustrating a configuration of the phased array antenna 1.

(10) As illustrated in FIG. 1, the phased array antenna 1 is a transmitting antenna which includes n antenna elements A1, A2, . . . and An; n feeding circuits F1, F2, . . . and Fn; and one multiplexer MP. Note here that n represents any integer not less than 2; FIG. 1 illustrates a configuration where n=4.

(11) The multiplexer MP adds an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t) so as to generate a sum signal V.sub.IF+LO(t) which equals V.sub.IF(t)+V.sub.LO(t). The intermediate frequency signal V.sub.IF(t), the local signal V.sub.LO(t), and the sum signal V.sub.IF+LO(t) can be expressed by, for example, the following formulas.
[Math. 1]
V.sub.IF(t)=V.sub.1 cos(2f.sub.IF(t+.sub.IF))(1)
[Math. 2]
V.sub.L0(t)=V.sub.0 cos(2f.sub.LO(t+.sub.LO))(2)
[Math. 3]
V.sub.IF+LO(t)=V.sub.1 cos(2f.sub.IF(t+.sub.IF))+V.sub.0 cos(2f.sub.LO(t+.sub.LO))(3)

(12) As illustrated in FIG. 1, each feeding circuit Fi (i=1, 2, . . . n) includes a time delay element TDi, a demultiplexer DPi, and a mixer for transmission (hereinafter simply referred to as a transmission mixer) TMXi. Note that in FIG. 1, reference signs have been provided only for the time delay element TD1, the demultiplexer DP1, and the transmission mixer TMX1 of feeding circuit F1 because each feeding circuit Fi is configurationally identical.

(13) The time delay element TDi generates a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.IF+LO(t). In a case where the sum signal V.sub.IF+LO(t) is expressed as in Formula (3), the delayed sum signal V.sub.IF+LO(tti) is expressed as shown below. Possible examples of the time delay element TDi include a switched line in which feed lines of differing lengths are switched to in accordance with a desired time delay. Furthermore, as described later, the length of the time delay ti imparted by the time delay element TDi is set in accordance with the direction of a main beam of radiated electromagnetic waves.
[Math. 4]
V.sub.IF+LO(tti)=V.sub.1 cos(2f.sub.IF(tti+.sub.IF))+V.sub.0 cos(2f.sub.LO(tti+.sub.LO))(4)

(14) The demultiplexer DPi generates a delayed intermediate frequency signal V.sub.IF(tti) and a delayed local signal V.sub.LO(tti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti). In a case where the delayed sum signal V.sub.IF+LO(tti) is expressed as in Formula (4), the delayed intermediate frequency signal V.sub.IF(tti) and the delayed local signal V.sub.LO(tti) are expressed as shown below.
[Math. 5]
V.sub.IF(tti)=V.sub.1 cos(2f.sub.IF(tti+.sub.IF))(5)
[Math. 6]
V.sub.LO(tti)=V.sub.0 cos(2f.sub.LO(tti+.sub.LO))(6)

(15) The transmission mixer TMXi generates a delayed radio frequency signal V.sub.RF(tti) by multiplying the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LO(tti). In a case where the delayed intermediate frequency signal V.sub.IF(tti) and the delayed local signal V.sub.LO(tti) are expressed as in Formula (5) and Formula (6), the delayed radio frequency signal V.sub.RF(tti) is expressed as shown in Formula (7).

(16) $\left[\mathrm{Math}.7\right]$$\begin{array}{cc}{V}_{\mathrm{RF}}\left(t\right)=A\frac{V_0{V}_1}{2}\cos \left(2\left(f_{\mathrm{LO}}+f_{\mathrm{IF}}\right)\left(t-\mathrm{ti}+\frac{f_{\mathrm{LO}}{}_{\mathrm{LO}}+f_{\mathrm{IF}}{}_{\mathrm{IF}}}{f_{\mathrm{LO}}+f_{\mathrm{IF}}}\right)\right)& \left(7\right)\end{array}$

(17) The feeding circuit Fi supplies the delayed radio frequency signal V.sub.RF(tti) generated by the transmission mixer TMXi to a corresponding antenna element Ai.

(18) The time delay ti in each feeding circuit Fi can be set in a manner similar to that in a conventional phased array antenna. For example, in a case where the antenna elements A1, A2, . . . and An are arranged in this order along the same straight line, the time delay ti in each feeding circuit Fi can be set as shown in Formula (8), in accordance with the direction of the main beam of radiated electromagnetic waves. In Formula (8), c represents the speed of light, and di represents a distance between the antenna element A1 and an antenna element Ai. Furthermore, is an angle formed by (i) the straight line along which the antenna elements A1, A2, . . . and An are arranged and (ii) an equiphase plane of radiated electromagnetic waves.

(19) $\left[\mathrm{Math}.8\right]$$\begin{array}{cc}\mathrm{ti}=\mathrm{di}\frac{\sin }{c}& \left(8\right)\end{array}$

(20) For example, in a case where an electromagnetic wave in the 60 GHz band (not less than 57 GHz and not more than 66 GHz) is radiated, a distance between adjacent ones of the antenna elements can, for example, be set to of a free space wavelength corresponding to a center frequency of 61.5 GHz, that is, be set to 2.44 mm. In other words, the distance di between the antenna element A1 and the antenna element Ai can be set to 2.44(i1) mm. In this configuration, the time delay ti in each feeding circuit Fi can be set to 5.7(i1) ps in order to incline a radiation direction such that the angle becomes 45, the angle being formed by (i) the straight line along which the antenna elements A1, A2, . . . and An are arranged and (ii) the equiphase plane of radiated electromagnetic waves.

(21) In order to achieve the phased array antenna 1 in which 60 beam scanning in the 60 GHz band is possible, the phased array antenna 1 can be configured such that, for example, (i) the antenna elements A1, A2, . . . and An are arranged at intervals of 2.4 mm along the same straight line, and (ii) an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t) each having a 9 GHz bandwidth are used. In order to achieve the phased array antenna 1 in which 45 beam scanning in the 60 GHz band is possible, the phased array antenna 1 can be configured such that, for example, (i) the antenna elements A1, A2, . . . and An are arranged at intervals of 2.6 mm along the same straight line, and (ii) an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t) each having a 9 GHz bandwidth are used.

(22) In a case where an electromagnetic wave in the 70 GHz band (not less than 71 GHz and not more than 76 GHz) is radiated, a distance between adjacent ones of the antenna elements can, for example, be set to of a free space wavelength corresponding to a center frequency of 73.5 GHz, that is, be set to 2.04 mm. In other words, the distance di between the antenna element A1 and the antenna element Ai can be set to 2.04(i1) mm. In this configuration, the time delay ti in each feeding circuit Fi can be set to 4.8(i1) ps in order to incline a radiation direction such that the angle becomes 45, the angle being formed by (i) the straight line along which the antenna elements A1, A2, . . . and An are arranged and (ii) the equiphase plane of radiated electromagnetic waves.

(23) In order to achieve the phased array antenna in which 60 beam scanning in the 70 GHz band is possible, the phased array antenna can be configured such that, for example, (i) the antenna elements A1, A2, . . . and An are arranged at intervals of 2.1 mm along the same straight line, and (ii) an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t) each having a 5 GHz bandwidth are used. In order to achieve the phased array antenna in which 45 beam scanning in the 70 GHz band is possible, the phased array antenna can be configured such that, for example, (i) the antenna elements A1, A2, . . . and An are arranged at intervals of 2.3 mm along the same straight line, and (ii) an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t) each having a 5 GHz bandwidth are used.

(24) A noteworthy point of the phased array antenna 1 is that an amount of time delay in the delayed radio frequency signal V.sub.RF(tti) inputted into each antenna element Ai is not dependent on frequency. As such, with the phased array antenna 1, even if the frequency of radiated electromagnetic waves is changed, the electromagnetic waves can be radiated in a constant direction, without a change in the amount of time delay ti in each feeding circuit Fi.

(25) For example, in a case where the time delay ti in each feeding circuit Fi is set to be 5.7(i1) ps, it is possible to set the angle to be 45, independently of the frequency of radiated electromagnetic waves. In a case where the time delay ti in each feeding circuit Fi is set to be 4.8(i1) ps, it is also possible to set the angle to be 45, independently of the frequency of radiated electromagnetic waves.

(26) Note that a signal source IF of the intermediate frequency signal V.sub.IF(t) and a signal source LO of the local signal V.sub.LO(t) can each be a component included in the phased array antenna 1, but do not have to be. Furthermore, a control section (not shown) which controls the time delay ti in each feeding circuit Fi can be a component included in the phased array antenna 1, but does not have to be.

(27) Furthermore, it is possible to use, as a feeding device for a phased array antenna, a device obtained by removing the antenna elements A1, A2, . . . and An from the phased array antenna 1, that is, a device which includes (i) the n feeding circuits F1, F2, . . . and Fn and (ii) one multiplexer MP.

(28) In each feeding circuit Fi, it is also possible to provide, between the demultiplexer DPi and the transmission mixer TMXi, a multiplier which multiplies the frequency of the delayed local signal V.sub.LO(tti). In such a configuration, a delayed local signal V.sub.LOM(tti) inputted into the transmission mixer TMXi is expressed by Formula (9), and the delayed radio frequency signal V.sub.RF(tti) generated by the transmission mixer TMXi is expressed by Formula (10). In these formulas, k represents any integer not less than 2, and can be, for example, 2 or 3. Even with such a configuration, the amount of time delay in the delayed radio frequency signal V.sub.RF(tti) is not dependent on frequency.

(29) $\left[\mathrm{Math}.9\right]$$\begin{array}{cc}{V}_{\mathrm{LOM}}\left(t-\mathrm{ti}\right)=V_0\cos \left(2f_{\mathrm{LO}}\left(t-\mathrm{ti}+{}_{\mathrm{LO}}\right)k\right)\left[\mathrm{Math}.10\right]& \left(9\right)\\ V_{\mathrm{RF}}\left(t-\mathrm{ti}\right)=A\frac{V_0{V}_1}{2}\cos \left(2\left({\mathrm{kf}}_{\mathrm{LO}}+f_{\mathrm{IF}}\right)\left(t-\mathrm{ti}+\frac{{\mathrm{kf}}_{\mathrm{LO}}{}_{\mathrm{LO}}+f_{\mathrm{IF}}{}_{\mathrm{IF}}}{{\mathrm{kf}}_{\mathrm{LO}}+f_{\mathrm{IF}}}\right)\right)& \left(10\right)\end{array}$

Embodiment 2

(30) The following description will discuss, with reference to FIG. 2, a phased array antenna 2 in accordance with Embodiment 2 of the present invention. FIG. 2 is a block diagram illustrating a configuration of the phased array antenna 2.

(31) The phased array antenna 2 is a transmitting and receiving antenna which is obtained by adding components for receiving to the phased array antenna 1, which is a transmitting antenna. As illustrated in FIG. 2, each feeding circuit Fi of the phased array antenna 2 includes, as components for reception, a first mixer for reception (hereinafter simply referred to as a first reception mixer) RMX1i and a second mixer for reception (hereinafter simply referred to as a second reception mixer) RMX2i. Each feeding circuit Fi also includes circulators C1i through C3i, which are components for enabling both transmitting and receiving. Note that in FIG. 2, reference signs have been provided only for the components of the feeding circuit F1 because each feeding circuit Fi is configurationally identical.

(32) The first reception mixer RMX1i generates a difference frequency signal V.sub.k(t+ti) by multiplying a radio frequency signal V.sub.RF(t+ti) by a doubled-frequency local signal V.sub.LO2(t). Here, the radio frequency signal V.sub.RF(t+ti) is a radio frequency signal which has been received by use of a corresponding antenna element Ai. The doubled-frequency local signal V.sub.LO2(t) is a local signal whose frequency is twice that of a local signal V.sub.LO(t). The radio frequency signal V.sub.RF(t) is expressed as shown in Formula (11), and the difference frequency signal V.sub.k(t+ti) is expressed as shown in Formula (12). Note here that ti is equal to ti(f.sub.LO+f.sub.IF)/(f.sub.LOf.sub.IF).
[Math. 11]
V.sub.RF(t+ti)=A cos(2(kf.sub.LO+f.sub.IF)(t+ti))(11)
[Math. 12]
V.sub.k(t+ti)=A.sub.1 cos(2(f.sub.LOf.sub.IF)t2(f.sub.LO+f.sub.IF)ti)(12)

(33) The second reception mixer RMX2i generates an intermediate frequency signal V.sub.IF(t+ti) by multiplying the difference frequency signal V.sub.k(t+ti) by a delayed local signal V.sub.LO(tti). Since the difference frequency signal V.sub.k(t) is expressed as shown in Formula (12), the intermediate frequency signal V.sub.IF(t+ti) is expressed as shown in Formula (13).
[Math. 13]
V.sub.IF(t+ti)=A.sub.2 cos(2f.sub.IF(t+ti))(13)

(34) The time delay element TDi generates a delayed intermediate frequency signal V.sub.IF(t) by imparting a time delay ti to the intermediate frequency signal V.sub.IF(t+ti). Since the intermediate frequency signal V.sub.IF(t+ti) is expressed as shown in Formula (13), the delayed intermediate frequency signal V.sub.IF(t) is expressed as shown in Formula (14). The delayed intermediate frequency signal V.sub.IF(t) is supplied to a receiving circuit R.
[Math. 14]
V.sub.IF(t)=A.sub.2 cos(2f.sub.IF(t))(14)

(35) The circulator C1i is provided between a transmission mixer TMXi and the antenna element Ai and is connected to the first reception mixer RMX1i. The circulator C1i supplies, to the antenna element Ai, a delayed radio frequency signal V.sub.RF(tti) outputted from the transmission mixer TMXi (operation during transmission). The circulator C1i also supplies, to the first reception mixer RMX1i, the radio frequency signal V.sub.RF(t+ti) outputted from the antenna element Ai (operation during reception).

(36) The circulator C2i is provided between the time delay element TDi and a demultiplexer DPi and is connected to the second reception mixer MR2i. The circulator C2i supplies, to the demultiplexer DPi, a delayed sum signal V.sub.IF+LO(tti) outputted from the time delay element TDi (operation during transmission). The circulator C2i also supplies, to the time delay element TDi, the intermediate frequency signal V.sub.IF(t+ti) outputted from the second reception mixer MR2i (operation during reception).

(37) The circulator C3i is provided between a multiplexer MP and the time delay element TDi and is connected to the receiving circuit R. The circulator C3i supplies, to the time delay element TDi, a sum signal V.sub.IF+LO(t) outputted from the multiplexer MP (operation during transmission). The circulator C3i also supplies, to the receiving circuit R, the delayed intermediate frequency signal V.sub.IF(t) outputted from the time delay element TDi (operation during reception).

(38) A noteworthy point of the phased array antenna 2 is that the delayed intermediate frequency signal V.sub.IF(t) obtained from each feeding circuit Fi does not include ti, and each delayed intermediate frequency signal V.sub.IF(t) is an identical signal expressed by Formula (14). This makes it possible to also use the phased array antenna 2 as a highly sensitive receiving antenna.

(39) Note that a signal source IF of an intermediate frequency signal V.sub.IF(t), a signal source LO of the local signal V.sub.LO(t), and a signal source LO2 of the doubled-frequency local signal V.sub.LO2(t) can each be a component included in the phased array antenna 2, but do not have to be. Furthermore, it is possible to use, as a feeding device for a phased array antenna, a device obtained by removing the antenna elements A1, A2, . . . and An from the phased array antenna 2, that is, a device which includes (i) the n feeding circuits F1, F2, . . . and Fn and (ii) one multiplexer MP.

Embodiment 3

(40) The following description will discuss, with reference to FIG. 3, a phased array antenna 3 in accordance with Embodiment 3 of the present invention. FIG. 3 is a block diagram illustrating a configuration of the phased array antenna 3.

(41) The phased array antenna 3 is a transmitting and receiving antenna which is obtained by adding components for receiving to the phased array antenna 1, which is a transmitting antenna. As illustrated in FIG. 3, each feeding circuit Fi of the phased array antenna 3 includes, as components for reception, a first reception mixer RMX1i, a multiplexer for reception (hereinafter simply referred to as a reception multiplexer) RMPi, a demultiplexer for reception (hereinafter simply referred to as a reception demultiplexer) RDPi, and a second reception mixer RMX2i. Each feeding circuit Fi also includes circulators C1i through C3i, which are components for enabling both transmitting and receiving. Note that in FIG. 3, reference signs have been provided only for the components of the feeding circuit F1 because each feeding circuit Fi is configurationally identical.

(42) The first reception mixer RMX1i generates an intermediate frequency signal V.sub.IF(t+ti) by multiplying a radio frequency signal V.sub.RF(t+ti) by a delayed local signal V.sub.LO(tti). Here, the radio frequency signal V.sub.RF(t+ti) is a radio frequency signal which has been received by use of a corresponding antenna element Ai. The radio frequency signal V.sub.RF(t+ti) is expressed as shown in Formula (15), and the intermediate frequency signal V.sub.IF(t+ti) is expressed as shown in Formula (16). Note here that ti is equal to ti(2f.sub.LO+f.sub.IF)/f.sub.IF.
[Math. 15]
V.sub.RF(t+ti)=A cos(2(f.sub.LO+f.sub.IF)(t+ti))(15)
[Math. 16]
V.sub.IF(t+ti)=A.sub.1 cos(2f.sub.IF(t+ti)+22f.sub.LOti)(16)

(43) The reception multiplexer RMPi generates a sum signal V.sub.IF+LO(t) by adding the intermediate frequency signal V.sub.IF(t+ti) and the delayed local signal V.sub.LO(tti). Since the intermediate frequency signal V.sub.IF(t+ti) is expressed as shown in Formula (16), the sum signal V.sub.IF+LO(t) is expressed as shown in Formula (17).
[Math. 17]
V.sub.IF+LO(t)=A.sub.1 cos(2f.sub.IF(t+ti)+22f.sub.LOti)+A.sub.1 cos(2f.sub.LO(tti))(17)

(44) A time delay element TDi generates a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.IF+LO(t). Since the sum signal V.sub.IF+LO(t) is expressed as shown in Formula (17), the delayed sum signal V.sub.IF+LO(tti) is expressed as shown in Formula (18).
[Math. 18]
V.sub.IF+LO(tti)=A.sub.1 cos(2f.sub.IFt+22f.sub.LOti)+A.sub.1 cos(2f.sub.LO(tti))(18)

(45) The reception demultiplexer RDPi generates a delayed intermediate frequency signal V.sub.IF(t+titi) and a doubly delayed local signal V.sub.LO(t2ti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti). Since the delayed sum signal V.sub.IF+LO(tti) is expressed as shown in Formula (18), the delayed intermediate frequency signal V.sub.IF(t+titi) and the doubly delayed local signal V.sub.LO(t2ti) are expressed as shown in Formulas (19) and (20), respectively.
[Math. 19]
V.sub.IF(t+titi)=A.sub.1 cos(2f.sub.IFt+22f.sub.LOti)(19)
[Math. 20]
V.sub.LO(t2ti)=A.sub.1 cos(2f.sub.LO(t2ti))(20)

(46) The second reception mixer RMX2i generates a delayed radio frequency signal V.sub.RF(t) by multiplying the delayed intermediate frequency signal V.sub.IF(t+titi) by the doubly delayed local signal V.sub.LO(t2ti). Since the delayed intermediate frequency signal V.sub.IF(t+titi) and the doubly delayed local signal V.sub.LO(t2ti) are expressed as shown in Formulas (19) and (20), the delayed radio frequency signal V.sub.RF(t) is as expressed as shown in Formula (21).
[Math. 21]
V.sub.RF(t)=A.sub.2 cos(2(f.sub.IF+f.sub.LO)t)(21)

(47) The circulator C1i is provided between a transmission mixer TMXi and the antenna element Ai and is connected to the first reception mixer RMX1i. The circulator C1i supplies, to the antenna element Ai, a delayed radio frequency signal V.sub.RF(tti) outputted from the transmission mixer TMXi (operation during transmission). The circulator C1i also supplies, to the first reception mixer RMX1i, the radio frequency signal V.sub.RF(t+ti) outputted from the antenna element Ai (operation during reception).

(48) The circulator C2i is provided between the time delay element TDi and a demultiplexer DPi and is connected to the reception multiplexer RMPi. The circulator C2i supplies, to the demultiplexer DPi, a delayed sum signal V.sub.IF+LO(tti) outputted from the time delay element TDi (operation during transmission). The circulator C2i also supplies, to the time delay element TDi, the sum signal V.sub.IF+LO(t) outputted from the reception multiplexer RMPi (operation during reception).

(49) The circulator C3i is provided between a multiplexer MP and the time delay element TDi and is connected to the reception demultiplexer RDPi. The circulator C3i supplies, to the time delay element TDi, a sum signal V.sub.IF+LO(t) outputted from the multiplexer MP (operation during transmission). The circulator C3i also supplies, to the reception demultiplexer RDPi, the delayed sum signal V.sub.IF+LO(tti) outputted from the time delay element TDi (operation during reception).

(50) A noteworthy point of the phased array antenna 3 is that the delayed radio frequency signal V.sub.RF(t) obtained from each feeding circuit Fi does not include ti, and each delayed radio frequency signal V.sub.RF(t) is an identical signal expressed by Formula (21). This makes it possible to also use the phased array antenna 3 as a highly sensitive receiving antenna.

(51) Note that a signal source IF of an intermediate frequency signal V.sub.IF(t) and a signal source LO of a local signal V.sub.LO(t) can each be a component included in the phased array antenna 3, but do not have to be. Furthermore, it is possible to use, as a feeding device for a phased array antenna, a device obtained by removing the antenna elements A1, A2, . . . and An from the phased array antenna 3, that is, a device which includes (i) then feeding circuits F1, F2, . . . and Fn and (ii) one multiplexer MP.

Embodiment 4

(52) The following description will discuss, with reference to FIG. 4, a phased array antenna 4 in accordance with Embodiment 4 of the present invention. FIG. 4 is a block diagram illustrating a configuration of the phased array antenna 4.

(53) The phased array antenna 4 is a transmitting and receiving antenna which is obtained by adding components for receiving to the phased array antenna 1, which is a transmitting antenna. As illustrated in FIG. 4, each feeding circuit Fi of the phased array antenna 4 includes, as components for reception, a first reception mixer RMX1i, a reception multiplexer RMPi, a reception demultiplexer RDPi, and a second reception mixer RMX2i. Each feeding circuit Fi also includes circulators C1i through C3i, which are components for enabling both transmitting and receiving. Note that in FIG. 4, reference signs have been provided only for the components of the feeding circuit F1 because each feeding circuit Fi is configurationally identical.

(54) The first reception mixer RMX1i generates an intermediate frequency signal V.sub.IF(t+ti) by multiplying a radio frequency signal V.sub.RF(t+ti) by a local signal V.sub.LO(t). Here, the radio frequency signal V.sub.RF(t+ti) is a radio frequency signal which has been received by use of a corresponding antenna element Ai. A radio frequency signal V.sub.RF(t) is expressed as shown in Formula (22), and an intermediate frequency signal V.sub.IF(t) is expressed as shown in Formula (23). Note here that ti is equal to ti(f.sub.LO+f.sub.IF)/f.sub.IF.
[Math. 22]
V.sub.RF(t+ti)=A cos(2(f.sub.LO+f.sub.IF)(t+ti))(22)
[Math. 23]
V.sub.IF(t+ti)=A.sub.1 cos(2f.sub.IF(t+ti)+2f.sub.LOti)(23)

(55) The reception multiplexer RMPi generates a sum signal V.sub.IF+LO(t) by adding the intermediate frequency signal V.sub.IF(t+ti) and the local signal V.sub.LO(t). Since the intermediate frequency signal V.sub.IF(t+ti) is expressed as shown in Formula (23), the sum signal V.sub.IF+LO(t) is expressed as shown in Formula (24).
[Math. 24]
V.sub.IF+LO(t)=A.sub.1 cos(2f.sub.IF(t+ti)+2f.sub.LOti)+A.sub.1 cos(2f.sub.LOt)(24)

(56) The time delay element TDi generates a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.k+LO(t). Since the sum signal V.sub.IF+LO(t) is expressed as shown in Formula (24), the delayed sum signal V.sub.IF+LO(tti) is expressed as shown in Formula (25).
[Math. 25]
V.sub.IF+LO(tti)=A.sub.1 cos(2f.sub.IFt+2f.sub.LOti)+A.sub.1 cos(2f.sub.LO(tti))(25)

(57) The reception demultiplexer RDPi generates a delayed intermediate frequency signal V.sub.IF(t+tti) and a delayed local signal V.sub.LO(tti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti). Since the delayed sum signal V.sub.k+LO(tti) is expressed as shown in Formula (25), the delayed intermediate frequency signal V.sub.IF(t+tti) and the delayed local signal V.sub.LO(tti) are expressed as shown in Formulas (26) and (27), respectively.
[Math. 26]
V.sub.IF(t+titi)=A.sub.1 cos(2f.sub.IFt+2f.sub.LOti)(26)
[Math. 27]
V.sub.LO(tti)=A.sub.1 cos(2f.sub.LO(tti))(27)

(58) The second reception mixer RMX2i generates a delayed radio frequency signal V.sub.RF(t) by multiplying the delayed intermediate frequency signal V.sub.IF(t+tti) by the delayed local signal V.sub.LO(tti). Since the delayed intermediate frequency signal V.sub.IF(t+tti) and the delayed local signal V.sub.LO(tti) are expressed as shown in Formulas (26) and (27), the delayed radio frequency signal V.sub.RF(t) is expressed as shown in Formula (28).
[Math. 28]
V.sub.RF(t)=A.sub.2 cos(2(f.sub.IF+f.sub.LO)t)(28)

(59) The circulator C1i is provided between a transmission mixer TMXi and the antenna element Ai and is connected to the first reception mixer RMX1i. The circulator C1i supplies, to the antenna element Ai, a delayed radio frequency signal V.sub.RF(tti) outputted from the transmission mixer TMXi (operation during transmission). The circulator C1i also supplies, to the first reception mixer RMX1i, the radio frequency signal V.sub.RF(t+ti) outputted from the antenna element Ai (operation during reception).

(60) The circulator C2i is provided between the time delay element TDi and a demultiplexer DPi and is connected to the reception multiplexer RMPi. The circulator C2i supplies, to the demultiplexer DPi, a delayed sum signal V.sub.IF+LO(tti) outputted from the time delay element TDi (operation during transmission). The circulator C2i also supplies, to the time delay element TDi, the sum signal V.sub.IF+LO(t) outputted from the reception multiplexer RMPi (operation during reception).

(61) The circulator C3i is provided between a multiplexer MP and the time delay element TDi and is connected to the reception demultiplexer RDPi. The circulator C3i supplies, to the time delay element TDi, a sum signal V.sub.IF+LO(t) outputted from the multiplexer MP (operation during transmission). The circulator C3i also supplies, to the reception demultiplexer RDPi, the delayed sum signal V.sub.IF+LO(tti) outputted from the time delay element TDi (operation during reception).

(62) A noteworthy point of the phased array antenna 4 is that the delayed radio frequency signal V.sub.RF(t) obtained from each feeding circuit Fi does not include ti, and each delayed radio frequency signal V.sub.RF(t) is an identical signal expressed by Formula (28). This makes it possible to also use the phased array antenna 4 as a highly sensitive receiving antenna.

(63) Note that a signal source IF of an intermediate frequency signal V.sub.IF(t) and two signal sources LO of a local signal V.sub.LO(t) can each be a component included in the phased array antenna 4, but do not have to be. Furthermore, it is possible to use, as a feeding device for a phased array antenna, a device obtained by removing the antenna elements A1, A2, . . . and An from the phased array antenna 3, that is, a device which includes (i) the n feeding circuits F1, F2, . . . and Fn and (ii) one multiplexer MP.

Embodiment 5

(64) The following description will discuss, with reference to FIG. 5, a phased array antenna 5 in accordance with Embodiment 5 of the present invention. FIG. 5 is a block diagram illustrating a configuration of the phased array antenna 5.

(65) As illustrated in FIG. 5, the phased array antenna 5 is obtained by replacing the circulator C1i of the phased array antenna 2 of Embodiment 2 with a switch Si.

(66) The switch Si is controlled such that, during transmission, a transmission mixer TMXi and an antenna element Ai are connected, and a delayed radio frequency signal V.sub.RF(tti) outputted from the transmission mixer TMXi is supplied to the antenna element Ai. Furthermore, the switch Si is controlled such that, during reception, the antenna element Ai is connected to a first reception mixer RMX1i, and a radio frequency signal V.sub.RF(t+ti) outputted from the antenna element Ai is supplied to the first reception mixer RMX1i.

Embodiment 6

(67) The following description will discuss, with reference to FIG. 6, a phased array antenna 3 in accordance with Embodiment 6 of the present invention. FIG. 6 is a block diagram illustrating a configuration of the phased array antenna 3.

(68) As illustrated in FIG. 6, the phased array antenna 6 is obtained by replacing the circulator C1i of the phased array antenna 3 of Embodiment 3 with a switch Si.

(69) The switch Si is controlled such that, during transmission, a transmission mixer TMXi and an antenna element Ai are connected, and a delayed radio frequency signal V.sub.RF(tti) outputted from the transmission mixer TMXi is supplied to the antenna element Ai. Furthermore, the switch Si is controlled such that, during reception, the antenna element Ai is connected to a first reception mixer RMX1i, and a radio frequency signal V.sub.RF(t+ti) outputted from the antenna element Ai is supplied to the first reception mixer RMX1i.

Embodiment 7

(70) The following description will discuss, with reference to FIG. 7, a phased array antenna 7 in accordance with Embodiment 7 of the present invention. FIG. 7 is a block diagram illustrating a configuration of the phased array antenna 7.

(71) As illustrated in FIG. 7, the phased array antenna 7 is obtained by replacing the circulator C1i of the phased array antenna 4 of Embodiment 4 with a switch Si.

(72) The switch Si is controlled such that, during transmission, a transmission mixer TMXi and an antenna element Ai are connected, and a delayed radio frequency signal V.sub.RF(tti) outputted from the transmission mixer TMXi is supplied to the antenna element Ai. Furthermore, the switch Si is controlled such that, during reception, the antenna element Ai is connected to a first reception mixer RMX1i, and a radio frequency signal V.sub.RF(t+ti) outputted from the antenna element Ai is supplied to the first reception mixer RMX1i.

(73) [Recap]

(74) A phased array antenna in accordance with the above embodiments of the present invention includes: n (n is an integer of 2 or more) antenna elements A1, A2, . . . and An; n feeding circuits F1, F2, . . . and Fn; and a multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t), each feeding circuit Fi (i=1, 2, . . . n) including: a time delay element configured to generate a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.IF+LO(t); a demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(tti) and a delayed local signal V.sub.LO(tti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti); and a transmission mixer configured to generate a delayed radio frequency signal V.sub.RF(tti) by multiplying the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LO(tti), each feeding circuit Fi being configured to supply the delayed radio frequency signal V.sub.RF(tti) to a corresponding antenna element Ai.

(75) The above configuration makes it possible to provide a phased array antenna in which, in the band in which the phased array antenna is used, the time delay of the delayed radio frequency signal V.sub.RF(tti) supplied to each antenna element Ai is not dependent on frequency.

(76) The phased array antenna in accordance with the above embodiments can be arranged such that each feeding circuit Fi includes, instead of the transmission mixer: a multiplier configured to generate a delayed local signal V.sub.LOM(tti) by multiplying a frequency of the delayed local signal V.sub.LO(tti); and a transmission mixer configured to generate a delayed radio frequency signal V.sub.RF(tti) by multiplying the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LOM(tti).

(77) The above configuration makes it possible to provide a phased array antenna in which, in the band in which the phased array antenna is used, the time delay of the delayed radio frequency signal V.sub.RF(tti) supplied to each antenna element Ai is not dependent on frequency.

(78) The phased array antenna in accordance with the above embodiments can be preferably arranged such that each feeding circuit Fi further includes: a first reception mixer configured to generate a difference frequency signal V.sub.k(t+ti) by multiplying (a) a radio frequency signal V.sub.RF(t+ti) which has been received by use of the corresponding antenna element Ai by (b) a doubled-frequency local signal V.sub.LO2(t), whose frequency is twice that of the local signal V.sub.LO(t); and a second reception mixer configured to generate an intermediate frequency signal V.sub.IF(t+ti) by multiplying the difference frequency signal V.sub.k(t+ti) by the delayed local signal V.sub.LO(tti), and such that each feeding circuit Fi is configured to supply, to a receiving circuit, a delayed intermediate frequency signal V.sub.IF(t) obtained by imparting the time delay ti to the intermediate frequency signal V.sub.IF(t+ti) by use of the time delay element.

(79) The above configuration makes it possible to provide a transmitting and receiving phased array antenna in which, in the band in which the phased array antenna is used, the time delay of the delayed radio frequency signal V.sub.RF(tti) supplied to each antenna element Ai is not dependent on frequency.

(80) The phased array antenna in accordance with the above embodiments can be preferably arranged such that each feeding circuit Fi further includes: a first reception mixer configured to generate an intermediate frequency signal V.sub.IF(t+ti) by multiplying (a) a radio frequency signal V.sub.RF(t+ti) which has been received by use of the corresponding antenna element Ai by (b) the delayed local signal V.sub.LO(tti); a reception multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding the intermediate frequency signal V.sub.IF(t+ti) and the delayed local signal V.sub.LO(tti); a reception demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(t+titi) and a doubly delayed local signal V.sub.LO(t2ti) by demultiplexing a sum signal V.sub.IF+LO(tti), the sum signal V.sub.IF+LO(tti) being obtained by imparting the time delay ti to the sum signal V.sub.IF+LO(t) by use of the time delay element; and a second reception mixer configured to generate a delayed radio frequency signal V.sub.RF(t) by multiplying the delayed intermediate frequency signal V.sub.IF(t+titi) by the doubly delayed local signal V.sub.LO(t2ti), and such that each feeding circuit Fi is configured to supply the delayed radio frequency signal V.sub.RF(t) to a receiving circuit.

(81) The above configuration makes it possible to provide a transmitting and receiving phased array antenna in which, in the bandwidth in which the phased array antenna is used, the time delay of the delayed radio frequency signal V.sub.RF(tti) supplied to each antenna element Ai is not dependent on frequency.

(82) The phased array antenna in accordance with the above embodiments can be preferably arranged such that each feeding circuit Fi further includes: a first reception mixer configured to generate an intermediate frequency signal V.sub.IF(t+ti) by multiplying (a) a radio frequency signal V.sub.RF(t+ti) which has been received by use of the corresponding antenna element Ai by (b) the local signal V.sub.LO(t); a reception multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding the intermediate frequency signal V.sub.IF(t+ti) and the local signal V.sub.LO(t); a reception demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(t+titi) and a delayed local signal V.sub.LO(tti) by demultiplexing a delayed sum signal V.sub.IF+LO(tti), the delayed sum signal V.sub.IF+LO(tti) being obtained by imparting the time delay ti to the sum signal V.sub.IF+LO(t) by use of the time delay element; and a second reception mixer configured to generate a delayed radio frequency signal V.sub.RF(t) by multiplying the delayed intermediate frequency signal V.sub.IF(t+titi) by the delayed local signal V.sub.LO(tti), and such that each feeding circuit Fi is configured to supply the delayed radio frequency signal V.sub.RF(t) to a receiving circuit.

(83) The above configuration makes it possible to provide a transmitting and receiving phased array antenna in which, in the band in which the phased array antenna is used, the time delay of the delayed radio frequency signal V.sub.RF(tti) supplied to each antenna element Ai is not dependent on frequency.

(84) A feeding device in accordance with the above embodiments is a feeding device configured to supply a radio frequency signal to each of n (n is an integer of 2 or more) antenna elements A1, A2, . . . and An which are included in a phased array antenna, the feeding device including: n feeding circuits F1, F2, . . . and Fn; and a multiplexer configured to generate a sum signal V.sub.IF+LO(t) by adding an intermediate frequency signal V.sub.IF(t) and a local signal V.sub.LO(t), each feeding circuit Fi (i=1, 2, . . . n) including: a time delay element configured to generate a delayed sum signal V.sub.IF+LO(tti) by imparting a time delay ti to the sum signal V.sub.IF+LO(t); a demultiplexer configured to generate a delayed intermediate frequency signal V.sub.IF(tti) and a delayed local signal V.sub.LO(tti) by demultiplexing the delayed sum signal V.sub.IF+LO(tti); and a transmission mixer configured to generate a delayed radio frequency signal V.sub.RF(tti) by multiplying the delayed intermediate frequency signal V.sub.IF(tti) by the delayed local signal V.sub.LO(tti), each feeding circuit Fi being configured to supply the delayed radio frequency signal V.sub.RF(tti) to a corresponding antenna element Ai.

(85) The above configuration makes it possible to provide a phased array antenna in which, in the band in which the phased array antenna is used, the time delay of the delayed radio frequency signal V.sub.RF(tti) supplied to each antenna element Ai is not dependent on frequency.

ADDITIONAL MATTERS

(86) The present invention is not limited to the description of the embodiments or variations above, but may be altered within the scope of the claims. The present invention also encompasses, in its technical scope, any embodiment derived from an appropriate combination of technical means disclosed in differing embodiments or variations.

REFERENCE SIGNS LIST

(87) 1, 2, 3, and 4 Phased array antenna Ai Antenna element Fi Feeding circuit MP Multiplexer TDi Time delay element DPi Demultiplexer TMXi Transmission mixer