Measurement apparatus and method thereof

A measurement apparatus includes an anechoic chamber, a DUT board, rotation units, and a feeding arm. The anechoic chamber has inner-walls. Each inner-wall is covered with a radio wave absorber. One of the inner-wall is a first wall with an aperture and the other inner-walls are second walls. The DUT board holds a first antenna to be measured with radiation property and a probe to detect a signal from the first antenna. A part of the DUT board is inserted into the anechoic chamber through the aperture opened in the first wall. One end of the feeding arm holds a second antenna radiating a radio wave to the first antenna in the anechoic chamber. Each rotation unit provides on each second wall and is selectively attached to the other end of the feeding arm for rotating the second antenna and for feeding to the second antenna.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the Japanese Patent Application. No. 2009-000762, filed on Jan. 6, 2009, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a measurement apparatus and a method thereof.

2. Description of the Related Art

One of the techniques to measure radiation property of an antenna in three dimension is disclosed in JP-A 2004-7233249 (KOKAI). In this reference, an antenna to be measured rotates in an anechoic chamber.

However, when the antenna has a fine feeding structure such as being fed by a probe, it is difficult for the antenna to rotate connecting a needle of the probe into a chip implemented the antenna.

Other technique to measure radiation property is disclosed in JP-A 2006-53010 (KOKAI). In this reference, the antenna is fixed and connected to the probe. Moreover, an arch bridges over the antenna. The arch has a measuring antenna and rotates around the antenna. The measuring antenna transmits/receives radio wave to/from the antenna in order to measure radiation property of the antenna.

However, the antenna has a plural of panes and the radiation property of the antenna needs to be measured in each of the panes. When the radiation properties are measured with changing the pane of the antenna in the several measurements, the probe needs to be removed from the antenna and fixed on a plate, and then the probe is reconnected to the chip in each measuring of each of the panes.

Moreover, a same condition has to be replicated in all measuring in order to regard a measured data as an objective data.

As a result, labor effectiveness degrades because operation is complex and has to be performed carefully.

Described above, it is difficult for the antenna, which is fixed in the anechoic chamber and fed by the probe, to measure the radiation properties about the plural of panes.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a measurement apparatus includesan anechoic chamber having a plurality of inner-walls, each being covered with a radio wave absorber, one of the inner-wall being a first wall with an aperture and the other inner-walls being second walls;a DUT (Device Under Test) board to hold a first antenna to be measured with radiation property and a prove to detect a signal from the first antenna, at least a part of the DUT board being inserted into the anechoic chamber through the aperture opened in the first wall;a feeding arm, one end holding a second antenna radiating a radio wave to the first antenna in the anechoic chamber; anda plurality of rotation units, each provided on each of the second walls and being selectively attached to the other end of the feeding arm for rotating the second antenna and for feeding to the second antenna.

According to other aspect of the invention, a method for a measurement apparatus including an anechoic chamber which inside being covered with radio wave absorber, a DUT (Device Under Test) board which is inserted, into the anechoic chamber through an aperture opened in a first plane of the anechoic chamber, a probe hold which is placed on the DUT board and holds a probe feeding, rotation units, each being formed in one of planes of the anechoic chamber except the first plane, each being rotatable, and a feeding arm, one end being attached into and removed from the rotation units, other end holding an antenna, feeding to the antenna, comprising:setting a first antenna on the DUT board;setting a second antenna on the other end of the feeding arm;attaching the one end of the feeding arm into a first rotation unit;touching the probe to the first antenna;transmitting a signal from the second antenna with rotating the first rotation unit;receiving the signal at the first antenna;attaching the one end of the feeding arm into a second rotation unit;transmitting the signal from the second antenna with rotating the second rotation unit; andreceiving the signal at the first antenna.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments will be explained with reference to the accompanying drawings.

(Description of the First Embodiment)

As shown inFIG. 1, a measurement apparatus includes an anechoic chamber101, a DUT (Device Under Test) board102, a probe hold103, rotation units104-106, and a feeding arm107.

The anechoic chamber101has a plural of walls (six walls exist inFIG. 1). Each wall is covered with radio wave absorber (not shown). The radio wave absorber may be made of urethane absorbing carbon. The radio wave absorber may have a wave-shaped or a pyramid-shaped on its surface. An aperture111is opened at an almost center of one of the walls. The several walls (three walls inFIG. 1) have the rotation units104-106, respectively. The rotation units104-106can hold the feeding arm107. At least one wall has a door (not shown) which is able to be opened and closed. Size of the anechoic chamber101depends on a frequency of radio wave.

The DUT board102is placed as that a part of the DUT board102is inserted into the anechoic chamber101through the aperture111. The DUT board102holds a measured antenna (first antenna)109on its tip in the anechoic chamber101. The measured antenna109can be placed on the DUT board102through the door.

The probe hold103is placed on the DUT board102, and holds a probe110. The probe110feeds a signal to the measured antenna109. The measured antenna109may be an on-chip antenna or a bonding-wire antenna.

As shown inFIG. 2, needles are lined along the tip of the probe110to feed. Some of the needles correspond to a ground level and the others correspond to a signal level. As shown inFIG. 3, the needles are attached to a contact pad114which is formed on a semiconductor chip113. The measured antenna109is implemented into the semiconductor chip113. The semiconductor chip113and the measured antenna109are fed from the contact pad114.

One end of the feeding arm107is attached into and removed from the rotation units104-106. The other end of the feeding arm107is connected to a measuring antenna (second antenna)108and feeds to the measuring antenna108. The feeding arm107has a crank-shaped along the walls inside the anechoic chamber101as shown inFIG. 1. The feeding arm107is connected to any one of the rotation units104-106. The feeding arm107can be reconnected to another of the rotation units104-106through the door of the anechoic chamber101.

As shown inFIG. 4, the feeding arm107may be formed by a waveguide. The waveguide made of metal is suitable to support the measuring antenna108. Since the waveguide has small loss, measuring dynamic range can be improved especially in a high frequency band such as millimeter wave band.

The measuring antenna108may be a horn antenna.

The rotation units104-106are connected to motors (not shown), respectively. Then, the rotation units104-106are rotated by the motors which are controlled by a motor controller112. The motor controller112is placed outside the anechoic chamber101. The rotation units104-106are formed at locations as that the measured antenna109is located on a rotation axis of the motor.FIG. 5is a cross sectional view of the anechoic chamber101along a xz-plane ofFIG. 1. For example, the rotation units104-106and the measured antenna109are located as shown inFIG. 5. The rotation axis of the rotation units105is parallel to a y-axis.

FIG. 6is a cross sectional view of the anechoic chamber101along a xy-plane ofFIG. 1. The rotation units104-106and the measured antenna109are also located as shown inFIG. 6. The rotation axis of the rotation units106is parallel to a z-axis.

Similarly,FIG. 7is a cross sectional view of the anechoic chamber101along a yz-plane ofFIG. 1. The rotation units104-106and the measured antenna109are also located as shown inFIG. 7. The rotation axis of the rotation units104is parallel to a x-axis.

Since the probe110and the probe hold103are located at back of the measured antenna109, measuring accuracy degrades in the back of the measured antenna109. Therefore, the rotation units105,106may be placed at positions which are closer to the DUT board102from center of the anechoic chamber101. This realizes an easy setting of the measured antenna109to the DUT board102. Moreover, production cost and setting space can be reduced.

The rotation units104-106can be connected to the feeding arm107inside the anechoic chamber101and other device outside the anechoic chamber101. As shown inFIG. 8, the rotation units104-106may have a coaxial waveguide transformer121. The coaxial waveguide transformer121is fixed to each of the rotation units104-106, and connects the feeding arm (waveguide)107inside the anechoic chamber101with a coaxial cable122outside the anechoic chamber101. The coaxial waveguide transformer121is larger and hard to bend compared with the waveguide. Therefore, the coaxial waveguide transformer121can be firmly fixed into the rotation units104-106.

As shown inFIG. 9, the feeding arm107is connected to a signal generator131through any one of the rotation units104-106and the probe110is connected to a spectrum analyzer132in order to measure the radiation property of the measured antenna109. Then, a signal generated by the signal generator131is transmitted from the measuring antenna108rotating the rotation units104-106. The signal received by the measured antenna109is analyzed by the spectrum analyzer132.

As shown inFIG. 10, the feeding arm107may be connected to a port1of a network analyzer133through any one of the rotation units104-106and the probe110may be connected to a port2of the network analyzer133.

Since the feeding arm107has the crank-shaped, the measuring antenna108rotates around the measured antenna109keeping a constant distance between the measuring antenna108and the measured antenna109during rotation of the feeding arm107of which one end is connected to any one of the rotation units104-106. The radiation properties around the measured antenna109can be measured by rotation of the measuring antenna108. Moreover, the feeding arm107can keep being far from the measured antenna109in order to reduce giving influence to the measured antenna109.

The feeding arm107can be easily reconnected to another of the rotation units104-106through the door of the anechoic chamber101. Therefore, the radiation properties of different panes can be measured without touching the measured antenna109.

As show inFIG. 11, the radiation properties in the yz-plane may be measured by rotating the feeding arm107of which one end is connected to the rotation unit104. As show inFIG. 1, the radiation properties in the xz-plane may be measured by rotating the feeding arm107of which one end is connected to the rotation unit105. Similarly, as show inFIG. 12, the radiation properties in the xy-plane may be measured by rotating the feeding arm107of which one end is connected to the rotation unit106.

According to the first embodiment, the measurement apparatus can easily measure the radiation properties for the plural of panes with keeping fixed in the anechoic chamber.

As shown inFIG. 13, the feeding arm107may have a circular-shaped. The feeding arm can also keep a constant distance between the measuring antenna108and the measured antenna109when the radiation properties around the measured antenna109are measured.

The feeding arm107may have an U-shaped or other shapes which can keep the constant distance between the measuring antenna108and the measured antenna109.

As shown inFIG. 14, a rotary joint141can be used for the rotation units104-106in order to connect the feeding arm (waveguide)107inside the anechoic chamber101with an other device (waveguide)142outside the anechoic chamber101. One side of rotary joint141which is faced to inside the anechoic chamber101is rotated. On the other hand, the other side of the rotary joint141which is faced to outside the anechoic chamber101is fixed. Therefore, the rotary joint141can reduce distortion of transmission line and variation of electrical performance outside the anechoic chamber101.

As shown inFIG. 15, the feeding arm107may include a waveguide151(first waveguide) and a short waveguide152(second waveguide). The waveguide151has a crank-shaped. The short waveguide152is attached to and removed from a tip of the waveguide151. The short waveguide152may be a straight waveguide as shown inFIG. 16Aor a 90-degree twist waveguide as shown inFIG. 16B. Vertical-polarized wave and horizontal-polarized wave can be switched without attaching/removing whole the feeding arm107by replacing only the short waveguide152.

The feeding arm (waveguide)107may be connected to the measuring antenna108through a rotary joint. The vertical-polarized wave and the horizontal-polarized wave can be switched without attaching/removing whole the feeding arm107by rotating the rotary joint.

As shown inFIG. 17, when the feeding arm107is formed by a waveguide, a supporting member161may be used to support the waveguide. The waveguide made of metal may be bent by torque at end which is fixed to any one of the rotation units104-106. However, the supporting member161prevents the waveguide from bending. As a result, precision of rotation angle and the distance between the measuring antenna108and the measured antenna109may not degrade. For example, a concave slot is formed on the supporting member161and the feeding arm107is matching into the concave slot.

As shown inFIG. 18, the feeding arm107may be a structure including coaxial cable172along an arm171which is made of plastic. Production cost can be reduced by using the coaxial cable172as the transmission line, compared with using a waveguide as the feeding arm107which requires metal processing with high precision. Moreover, the distance between the measuring antenna108and the measured antenna109can easily vary by preparing several arms171which have different length.

When the feeding arm107uses the coaxial cable172as the transmission line, a rotary joint is useful to connect the coaxial cables172inside and outside the anechoic chamber101.

The feeding arm107may be covered with the radio wave absorber as same as inside of the anechoic chamber101. The rotation units104-106which are not connected to the feeding arm107may also be covered with the radio wave absorber. The probe hold103may also be covered with the radio wave absorber.

As shown inFIG. 19, the DUT board102may include a main plate181, a sub plate182, and a plastic screw183. A substrate (not shown) including the measured antenna109is inserted into a slit184which is formed between the main plate181and the sub plate182. Then, the substrate is fixed by the plastic screw183. This structure realizes longer distance between the DUT board102and the measured antenna109compared with the case that the measured antenna109is placed on the DUT board102. Therefore, influence due to scattered wave from the DUT board102can be reduced.

The DUT board102is not covered with the radio wave absorber, because it is close to the measured antenna109. Therefore, the DUT board102may be made of a material having low relative permittivity such as Teflon (Registered Trademark) in order to reduce the influence due to scattered wave from the DUT board102.

In above description, a signal is transmitted from the measuring antenna108which is fixed to the tip of the feeding arm107to the measured antenna109which is fixed on the DUT board102. Inversely, the signal may be transmitted from the measured antenna109to the measuring antenna108.

(Description of the Second Embodiment)

As shown inFIG. 20, a measurement apparatus is almost same as that of the first embodiment except that it further includes a microscope201and a support unit202. The support unit202supports the microscope201. The support unit202includes a shifting unit in order to shift the microscope201in a vertical direction. The sifting unit performs micro adjustment or coarse adjustment about how long the microscope201is shifted. The support unit202may include the shifting unit in order to shift the microscope201in a horizontal direction.

An aperture203is opened in top of the anechoic chamber101in order to set the microscope201inside the anechoic chamber101. The aperture203is formed above the measured antenna109placed on the DUT board102.

Other else components (except for the microscope201, the support unit202and the aperture203) are same as them of the first embodiment. Therefore, explanations about them are skipped.

The microscope201is used to see whether the needles along the tip of the probe110touch the contact pad formed on the semiconductor chip including the measured antenna109. The microscope201is connected to a monitor (not shown) outside the anechoic chamber101. Images from the microscope201are displayed on the monitor. An operator can see touching condition of the probe110by the monitor.

In general, focal length of the microscope201is about several [mm] to several dozen [mm]. The microscope201is set inside the anechoic chamber101through the aperture203and focus of the microscope201is adjusted by the support unit202.

Labor effectiveness is improved by performing contact the needles along the tip of the probe110to the contact pad with watching the monitor.

The microscope201is evacuated to outside the anechoic chamber101and the aperture203is closed during measurement of the radiation properties of the measured antenna109. This avoids generating scattered waves by the microscope201and happening a collision of the microscope201and the feeding arm107.

According to the second embodiment, the measurement apparatus can easily measure the radiation properties for the plural of panes with keeping fixed in the anechoic chamber. Moreover, the measurement apparatus improves labor effectiveness in the performing contact the needles along the tip of the probe110to the contact pad.

The measurement apparatus of the first. or second embodiment may be used to measure not only the radiation property of an antenna but also electromagnetic noise.