Permeability spectrum testing device and method for micron-sized sample based on near-field microwave probe

A permeability spectrum testing device for a micron-sized sample based on a near-field microwave probe, comprising the near-field microwave probe, a vector network analyzer (VNA), and a control system, wherein

• the near-field microwave probe comprises a microwave probe tip having a signal terminal and a ground terminal shorted;
• the near-field microwave probe is connected to a scattering parameter (S-parameter) testing port of the VNA;
• the VNA is connected to the control system;
• the near-field microwave probe directly faces a sample testing area;
• and the sample testing area is configured to place a target sample;
• a distance between the near-field microwave probe and the target sample is a first preset distance;
• the first preset distance is greater than 0 and less than 100 μm;
• the near-field microwave probe is configured to transmit a microwave signal between the target sample and the VNA;
• the near-field microwave probe is connected to the VNA to form an impedance loop;
• and when the impedance loop approaches to the target sample, an impedance of the impedance loop changes, followed by a change of an S-parameter of the VNA;
• the VNA is configured to receive reflected signals detected by the near-field microwave probe in four states, obtain S-parameters in the four states according to the reflected signals in the four states, and send the S-parameters in the four states to the control system;
• the four states comprises:
• the sample testing area is only in an unloaded state;
• the sample testing area is in the unloaded state with a magnetic field of a preset magnetic field intensity applied;
• the sample testing area only has the target sample;
• and the sample testing area has the target sample with a saturated magnetic field of a preset magnetic field direction applied;
• the control system is configured to determine a permeability spectrum of the target sample according to the S-parameters in the four states;
• and
• the permeability spectrum testing device for a micron-sized sample based on a near-field microwave probe is capable of testing the micron-sized sample or a microscopic area of a sample, thereby realizing a micro-area scanning resolution;
• and the permeability spectrum testing device for a micron-sized sample based on a near-field microwave probe has a test frequency of 20 GHz.