Calibration method for amplitude and phase variable array antenna

[0033] Such as figure 1 Shown is a structural diagram of an array antenna with variable amplitude and phase. In the figure, 3 is the antenna unit, 1 is the attenuator, and 2 is the phase shifter. By changing the state of the attenuator and the phase shifter, the amplitude and phase of the signal fed to each antenna unit can be changed. This work is controlled by the controller 5 To be done.

[0034] 4 is the power source. When the array antenna is in the transmitting mode, the power source feeds each antenna unit through the corresponding attenuator and phase shifter to transmit the array signal. The power source includes a power divider to divide a signal into multiple paths and feed it to each antenna unit. By setting the phase and amplitude of the signal of each antenna unit by the controller, a beam of the required specific shape can be formed and beam scanning can be realized. At this time, the auxiliary antenna 7 can be set in the far field range of the array antenna. When the array antenna is in the transmitting mode, the auxiliary antenna is used as a receiving antenna to receive the calibration signal. By detecting the signal received by the auxiliary antenna, the amplitude and phase characteristics of each antenna unit can be obtained.

[0035] figure 1 Middle 6 is the power load. When the array antenna is in the receiving mode, the auxiliary antenna serves as an external signal source to transmit a reference signal to the array antenna. The reference signal is sent to the power load via the phase shifter and attenuator of each antenna unit of the array antenna. As the receiving device, it includes a power synthesizer, which is used to synthesize the received multiple signals into one signal. In the same way, by setting the amplitude and phase of each antenna unit signal by the controller, a beam of the required specific shape can be formed and beam scanning can be realized. Detection is performed based on the reference signal received by the load, and the amplitude and phase of each antenna unit can also be obtained. characteristic.

[0036] Such as image 3 Shown is a flow chart of the method of the present invention. The method of the present invention uses the change information of the array signal of the attenuator and the phaser in different states to realize the joint calibration of the amplitude and the phase in multiple states. The calibration method is as follows:

[0037] First, an auxiliary receiving antenna needs to be set up at the far field of the array antenna. During calibration, the array antenna to be tested transmits signals, and the field vector generated by the nth antenna unit at the auxiliary receiving antenna is recorded as When the position between the array antenna under test and the auxiliary receiving antenna and other boundary conditions remain unchanged, the field vector does not change, then the field vector generated by the array antenna under test at the auxiliary receiving antenna is the field vector generated by each antenna element Superimposed sum, denoted as Such as figure 2 As shown, where n = 1, 2, 3... is the number of each antenna element in the array antenna, E n with Is the amplitude and phase of the initial field vector generated by each antenna element at the auxiliary receiving antenna, E 0 with Is the amplitude and phase of the initial composite field vector generated by the array antenna at the auxiliary receiving antenna.

[0038] Select the nth channel of the array antenna to be tested as the calibrated channel, assuming that the attenuation coefficient of the attenuator is l (l=a 0 , A 1 , A 2 ,..., a m ), each attenuation coefficient value corresponds to a working state of the attenuator, and the initial state of the attenuator is marked as a 0 , When the attenuation coefficient (that is, the state of the attenuator) of the attenuator connected to the calibrated channel becomes a 1 And a 2 The vector fields generated by the time array antenna are respectively (principle as figure 2 Shown):

[0039]

[0040]

[0041] Then the attenuator is at a 0 , A 1 , A 2 The signal power received by the auxiliary antenna in three different states can be expressed as:

[0042] P n 0 = | E → 0 | 2 = E 0 2 ,

[0043]

[0044]

[0045] Set the relative amplitude of the initial state of the tested channel E n E 0 = A n , Relative phase Then the state of the attenuator is a 1 And a 2 , The normalized value of the power received by the auxiliary receiving antenna relative to the initial power is R 1 And R 2 , The expression is as follows:

[0046]

[0047]

[0048] According to the attenuator in a 0 , A 1 , A 2 The signal response results in three different states can be obtained as A n with , The expression is as follows:

[0049] A n = a 2 ( R 2 - 1 ) - a 1 ( R 2 - 1 ) + R 2 - R 1 ( a 1 - 1 ) ( a 2 - 1 ) ( a 1 - a 2 )

[0050]

[0051] Obviously in order to get The exact value of, requires additional information, here you can consider changing the state of the phase shifter to obtain enough information, assuming that the state of the attenuator is a 2 , The phase shifter of the calibrated channel At this time, the received signal power of the auxiliary receiving antenna is recorded as Then it can be obtained from the aforementioned formulas:

[0052]

[0053]

[0054] According to the three states of the attenuator (a 0 , A 1 , A 2 ) And a state (90°) of the phase shifter, the relative phase of the measured channel can be obtained The expression is as follows:

[0055]

[0056] It can be seen from the foregoing that the inconsistency error of the initial amplitude and phase of the tested channel of the array antenna can be obtained only in 4 states (including the initial state) in three amplitude states plus one phase state.

[0057] Reselect the calibrated channel and repeat the above process to obtain the relative amplitude and relative phase of each antenna element in the array antenna. If the obtained relative amplitude and relative phase of each antenna element are inconsistent, adjust the attenuation coefficient of the channel where each antenna element is located. And the phase coefficient, that is, adjust the state of the corresponding attenuator and phaser to make it consistent.

[0058] The content that is not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.