Test apparatus and test method
There is provided a test apparatus that measures transmission characteristics or reception characteristics of a DUT having an antenna under test, and includes an anechoic box, a posture changeable mechanism 56 , a first test antenna 6 a and a second test antenna 6 b , for measuring the transmission characteristics or the reception characteristics of the DUT, a reflector that reflects a radio signal radiated by the first test antenna and converts the radio signal into a plane wave radio signal, and a movable antenna mechanism 60 that moves a position of the second test antenna such that the radio signal is transmitted to or received from the DUT installed in a far field at a plurality of angles of arrival, with reference to a radio-wave arrival direction from the first test antenna.
1. A test apparatus that measures transmission characteristics or reception characteristics of a device under test including an antenna under test, the apparatus comprising:
an anechoic box that has an internal space that is not influenced by a surrounding radio wave environment;
a posture changeable mechanism that sequentially changes a posture of the device under test disposed in a quiet zone in the internal space;
a first test antenna and a second test antenna that are accommodated in the internal space and transmit or receive radio signals to or from the antenna under test, for measuring the transmission characteristics or the reception characteristics of the device under test;
a reflector that reflects a radio signal radiated by the first test antenna and converts the radio signal into a plane wave radio signal; and
a movable antenna mechanism that moves a position of the second test antenna such that the radio signal is transmitted to or received from the device under test installed in a far field at a plurality of angles of arrival or a plurality of angles of departure, with reference to a radio-wave arrival direction from the first test antenna or a radio wave emission direction to the first test antenna.
2. The test apparatus according to claim 1 ,
wherein the movable antenna mechanism includes
an antenna holding unit that holds the second test antenna, and
a moving mechanism that moves the antenna holding unit on a circle.
3. The test apparatus according to claim 2 ,
wherein the antenna holding unit has a columnar fulcrum that holds the second test antenna, and
the fulcrum is tilted from a vertical direction such that one end portion of the fulcrum attached to the moving mechanism is closer to a center axis of the circle than the other end portion of the fulcrum.
4. The test apparatus according to claim 2 , further comprising:
a mirror that reflects a radio signal radiated from the second test antenna and transmits the radio signal to the antenna under test, and reflects a radio signal radiated from the antenna under test and transmits the radio signal to the second test antenna,
wherein the antenna holding unit holds the second test antenna and the mirror at an interval in a longitudinal direction.
5. The test apparatus according to claim 2 ,
wherein the moving mechanism includes
a linear motion unit that linearly moves a moving stand,
an arcuate rail,
a movable stand to which the antenna holding unit is fixed and which is movable along the rail, and
a link that connects the moving stand and the movable stand and moves the movable stand along the rail by linear movement of the moving stand, and
the link is connected to the moving stand such that a longitudinal direction of the link is consistently orthogonal to a moving direction of the moving stand.
6. The test apparatus according to claim 3 ,
wherein the moving mechanism includes
a linear motion unit that linearly moves a moving stand,
an arcuate rail,
a movable stand to which the antenna holding unit is fixed and which is movable along the rail, and
a link that connects the moving stand and the movable stand and moves the movable stand along the rail by linear movement of the moving stand, and
the link is connected to the moving stand such that an angle formed by a longitudinal direction of the link with respect to a moving direction of the moving stand is changed according to a position of the moving stand.
7. The test apparatus according to claim 2 ,
wherein the moving mechanism includes
a ring-shaped or arcuate rack having a plurality of teeth formed on an inner peripheral surface or an outer peripheral surface,
a pinion having a gear that engages with the teeth of the rack, and moving along the rack by being rotated by a rotation drive unit, and
a movable stand attached to the pinion, and
the antenna holding unit is attached to the movable stand.
8. The test apparatus according to claim 3 ,
wherein the moving mechanism includes
a ring-shaped or arcuate rack having a plurality of teeth formed on an inner peripheral surface or an outer peripheral surface,
a pinion having a gear that engages with the teeth of the rack, and rotationally moving the rack by being rotated by a rotation drive unit, and
a movable stand attached to the rack, and
the antenna holding unit is attached to the movable stand.
9. The test apparatus according to claim 3 , further comprising:
a mirror that reflects a radio signal radiated from the second test antenna and transmits the radio signal to the antenna under test, and reflects a radio signal radiated from the antenna under test and transmits the radio signal to the second test antenna,
wherein the antenna holding unit holds the second test antenna and the mirror at an interval in a longitudinal direction.
10. The test apparatus according to claim 4 ,
wherein the moving mechanism includes
a linear motion unit that linearly moves a moving stand,
an arcuate rail,
a movable stand to which the antenna holding unit is fixed and which is movable along the rail, and
a link that connects the moving stand and the movable stand and moves the movable stand along the rail by linear movement of the moving stand, and
the link is connected to the moving stand such that a longitudinal direction of the link is consistently orthogonal to a moving direction of the moving stand.
11. The test apparatus according to claim 4 ,
wherein the moving mechanism includes
a ring-shaped or arcuate rack having a plurality of teeth formed on an inner peripheral surface or an outer peripheral surface,
a pinion having a gear that engages with the teeth of the rack, and rotationally moving the rack by being rotated by a rotation drive unit, and
a movable stand attached to the rack, and
the antenna holding unit is attached to the movable stand.
12. A test method using a test apparatus that measures transmission characteristics or reception characteristics of a device under test including an antenna under test, the test apparatus including
an anechoic box that has an internal space that is not influenced by a surrounding radio wave environment,
a posture changeable mechanism that sequentially changes a posture of the device under test disposed in a quiet zone in the internal space,
a first test antenna and a second test antenna that are accommodated in the internal space and transmit or receive radio signals to or from the antenna under test, for measuring the transmission characteristics or the reception characteristics of the device under test,
a reflector that reflects a radio signal radiated by the first test antenna and converts the radio signal into a plane wave radio signal, and
a movable antenna mechanism that moves a position of the second test antenna such that the radio signal is transmitted to or received from the device under test installed in a far field at a plurality of angles of arrival or a plurality of angles of departure, with reference to a radio-wave arrival direction from the first test antenna or a radio wave emission direction to the first test antenna,
the method comprising:
a step of selecting one angle of arrival among a plurality of angles of arrival or one angle of departure among a plurality of angles of departure;
a step of moving the second test antenna by the movable antenna mechanism to have the selected angle of arrival or angle of departure;
a step of sequentially changing the posture of the device under test disposed in the quiet zone; and
a step of measuring the transmission characteristics or the reception characteristics of the device under test by using the first and second test antennae, each time the posture of the device under test is changed.