US 12,222,382 B2
Near-field test method, system, readable storage medium and computer
Dongcai Su, Zhongshan (CN); and Junwei Dong, Zhongshan (CN)
Assigned to FRAGRANT MOUNTAIN MICROWAVE CO., LTD., Guangdong Province (CN)
Filed by FRAGRANT MOUNTAIN MICROWAVE CO., LTD., Zhongshan (CN)
Filed on Sep. 30, 2022, as Appl. No. 17/958,318.
Claims priority of application No. 202111161940.5 (CN), filed on Sep. 30, 2021.
Prior Publication US 2023/0096422 A1, Mar. 30, 2023
Int. Cl. G01R 29/08 (2006.01)
CPC G01R 29/0892 (2013.01) 7 Claims
OG exemplary drawing
 
1. A near-field test system, comprising:
a computer; and;
a source of signal for generating test signals, a signal receiver, a mover and at least one probe respectively connected to the computer;
wherein the source of signal, the signal receiver, the probe and a device under test (DUT) form a closed loop;
the mover is used for accepting a control of the computer to cause a random relative motion between the DUT and the probe to generate multiple random test points;
when the probe is connected to the signal receiver, the source of signal is connected to the DUT; when the probe is connected to the source of signal, the signal receiver is connected to the DUT; the probe is used to collect electromagnetic field signals at the multiple random test points and transmit the electromagnetic field signals directly to the signal receiver or to the DUT and then the DUT to the signal receiver;
the signal receiver is used to analyze and process the electromagnetic field signals collected by the probe and transmit to the computer; and
the computer is used for:
in a selected coordinate system, controlling the mover to cause the random relative motion between the DUT and the probe to generate the multiple random test points that satisfy the near field;
determining one or more postures of the probe to obtain electromagnetic field coefficients of the probe corresponding to the postures of the probe respectively;
obtaining measured values of the electromagnetic field signals collected by the at least one probe after being analyzed and processed by the signal receiver so as to obtain a measured value set custom character, custom character={mi(j): 1≤i≤N, 1≤j≤K}, where mi(j) represents the measured values of the electromagnetic field signals when the probe is at a j posture and at the test point pi;
calculating electromagnetic field coefficients v of the DUT: wherein a sparse feature of the electromagnetic field coefficients v of the DUT to be determined is a convex function which is represented by f(v); according to Lorenz reciprocity theorem, there is a random linear relationship Av=custom character between the electromagnetic field coefficients v of the DUT and the measured value set custom character, the random linear relationship Av=custom character is used as a constraint or a penalty function in a domain optimization, combining the convex function f(v) and the random linear relationship Av=custom character into an algorithm of convex optimization;
when Av=custom character is used as the constraint, the algorithm of convex optimization is written as Expression (1):
Minimize f(v) subject to Av=custom character  Expression (1)
when Av=custom character is used as the penalty function, the algorithm of convex optimization is written as Expression (2):
Minimize f(v)+P(Av-custom character)  Expression (2)
where A is a random matrix, and elements of A are determined by positions of the random test points and the electromagnetic field coefficients of the probe at each posture; P(.) is a convex function, which increases with an increase of modulus of the vector Av-custom character, Expressions (1) and (2) are solved by the algorithm of convex optimization, and a variable v is calculated and is determined as the electromagnetic field coefficients v of the DUT; and
obtaining, according to the electromagnetic field coefficients v of the DUT, a far-field pattern of the DUT or an electric field and/or a magnetic field at any point outside the DUT.