JP5135410B2

JP5135410B2 - TIS measuring method and apparatus

Info

Publication number: JP5135410B2
Application number: JP2010234631A
Authority: JP
Inventors: 扶手代木; 尚志河村; 徹佐久間
Original assignee: Anritsu Corp
Current assignee: Anritsu Corp
Priority date: 2010-10-19
Filing date: 2010-10-19
Publication date: 2013-02-06
Anticipated expiration: 2030-10-19
Also published as: JP2012090049A

Description

本発明は、携帯電話機のような移動体無線端末の受信感度を評価するための全等方性感度ＴＩＳ（Total Isotropic Sensitivity）を、容易に且つ短時間に測定するための技術に関する。 The present invention relates to a technique for easily and quickly measuring a total isotropic sensitivity TIS (Total Isotropic Sensitivity) for evaluating reception sensitivity of a mobile radio terminal such as a mobile phone.

携帯電話機のような移動体無線端末の受信感度を評価するパラメータとしてＴＩＳがある。なお、このＴＩＳと同じ意味のパラメータとしてＴＲＳ（Total Radiated Sensitivity）と呼ぶこともあるが、以下の説明ではＴＩＳと記載する。 There is TIS as a parameter for evaluating the reception sensitivity of a mobile radio terminal such as a mobile phone. Note that TRS (Total Radiated Sensitivity) is sometimes referred to as a parameter having the same meaning as TIS, but is described as TIS in the following description.

ＴＩＳの定義について図８を用いて説明する。図８の（ａ）は導体接続測定の系を示し、（ｂ）は放射測定の系を示すものである。 The definition of TIS will be described with reference to FIG. FIG. 8A shows a conductor connection measurement system, and FIG. 8B shows a radiation measurement system.

導体接続測定の場合は、測定用端子を介した直結の測定系で、送信機１００から受信機１１０にデータで変調された信号を入力し、その入力レベルを高い方から低い方へ順次低下させていき、受信機１１０で復調されるデータのＢＥＲ（ビット誤り率）が規定値に達した時の入力電力Ｐｓで受信感度を規定する。 In the case of conductor connection measurement, a signal modulated with data is input from the transmitter 100 to the receiver 110 in a direct measurement system via a measurement terminal, and the input level is sequentially lowered from the higher to the lower. Then, the reception sensitivity is defined by the input power Ps when the BER (bit error rate) of the data demodulated by the receiver 110 reaches a specified value.

この測定法は測定用端子の存在を前提にしているが、携帯端末の小型化や低コスト化に伴い、測定用端子を持たないものが増えてくると上記測定法は使えず、受信機の感度を放射で測定しなければならなくなる。 This measurement method assumes the presence of a measurement terminal, but as the number of devices that do not have a measurement terminal increases with the miniaturization and cost reduction of mobile terminals, the above measurement method cannot be used, and the receiver Sensitivity must be measured by radiation.

一方、放射測定の場合は、（θ，φ）方向からθ偏波の平面波が電力ＥＩＳ_θ（θ，φ）で到来した状態で、受信機１１０で復調されるデータのＢＥＲ（ビット誤り率）が規定値に達する時の受信アンテナ１１１から受信機１１０への入力電力がＰｓであったとする。 On the other hand, in the case of radiation measurement, a BER (bit error rate) of data demodulated by the receiver 110 in a state where a plane wave of θ polarization arrives from the (θ, φ) direction with power EIS _θ (θ, φ). Assume that the input power from the receiving antenna 111 to the receiver 110 when P reaches the specified value is Ps.

θ、φの両偏波に対し、このような平面波が全空間から到来する散乱環境（各平面波は異なる方向でインコヒーレントとする）を考え、その中に理想的無指向性アンテナを配置して受信した全電力を空間平均したものをＴＩＳと定義する。 Considering the scattering environment in which such plane waves arrive from the entire space for both θ and φ polarizations (each plane wave is incoherent in a different direction), an ideal omnidirectional antenna is placed in it. A spatial average of all received power is defined as TIS.

即ち、θ、φの両偏波に対する受信アンテナの動作利得をそれぞれＧ_θ（θ，φ）、Ｇ_φ（θ，φ）とすると、θ偏波の平面波の電力ＥＩＳ_θ（θ，φ）と、φ偏波の平面波の電力ＥＩＳ_φ（θ，φ）は、以下のように表される。 That is, assuming that the operating gain of the receiving antenna for both polarizations of θ and φ is G _θ (θ, φ) and G _φ (θ, φ), respectively, the plane wave power EIS _θ (θ, φ) of θ polarization is , Φ-polarized plane wave power EIS _φ (θ, φ) is expressed as follows.

ＥＩＳ_θ（θ，φ）＝Ｐｓ／Ｇ_θ（θ，φ） ……（１）
ＥＩＳ_φ（θ，φ）＝Ｐｓ／Ｇ_φ（θ，φ） ……（２） EIS _θ (θ, φ) = Ps / G _θ (θ, φ) (1)
EIS _φ (θ, φ) = Ps / G _φ (θ, φ) (2)

また、上記定義からＴＩＳは、次式によって表される。なお、以下の式では、θ、φの関数であることを示す（θ，φ）を省略して記載する。 From the above definition, TIS is expressed by the following equation. In the following formula, (θ, φ) indicating that it is a function of θ, φ is omitted.

ＴＩＳ
＝４π／｛∫∫［（１／ＥＩＳ_θ）＋（１／ＥＩＳ_φ）］sinθdθdφ｝……（３） TIS
= 4π / {∫∫ [(1 / EIS θ) + (1 / EIS φ)] sinθdθdφ} ...... (3)

つまり、式（１）、（２）のＥＩＳを全空間で測定し、それを式（３）の分母のように積分することでＴＩＳが得られる。 That is, TIS can be obtained by measuring the EIS of equations (1) and (2) in the entire space and integrating it as in the denominator of equation (3).

なお、上記技術に関連して、アンテナの３次元ゲインパターンを測定し、その測定結果に基づいてＴＩＳを求める技術が、特許文献１に開示されている。 In connection with the above technique, Patent Document 1 discloses a technique for measuring a three-dimensional gain pattern of an antenna and obtaining a TIS based on the measurement result.

特開２００７−２３５９５９号公報JP 2007-235959 A

しかしながら、上記のように３次元の式（１）、（２）のＥＩＳを全空間で測定し、それを積分する方式では、測定結果を得るために大変な時間がかかるという問題があった（自動測定システムを用いても通常６時間かかると言われている）。 However, as described above, the method of measuring the EIS of the three-dimensional equations (1) and (2) in the whole space and integrating it has a problem that it takes a very long time to obtain the measurement result ( Even with an automatic measurement system, it is usually said to take 6 hours).

本発明は、この問題を解決し、ＴＩＳを極めて短時間に測定できるＴＩＳ測定方法および装置を提供することを目的としている。 An object of the present invention is to solve this problem and provide a TIS measurement method and apparatus capable of measuring TIS in an extremely short time.

前記目的を達成するために、本発明の請求項１のＴＩＳ測定方法は、
楕円をその２つの焦点を通る軸を中心に回転して得られる楕円球状で金属の壁面で囲まれた閉空間の一方の焦点の近傍に送信アンテナ（３）を配置し、他方の焦点の近傍に被測定物（１）を配置して、前記送信アンテナから出力された信号が前記被測定物に最大感度で受信されるように前記送信アンテナと前記被測定物の位置を調整する段階と、
前記送信アンテナに対して前記被測定物が受信可能なビット誤り率測定用の測定信号を供給するとともに、該測定信号を受信した前記被測定物の復調データ信号のビット誤り率を測定できる状態にして前記測定信号の供給電力を変化させ、該ビット誤り率が規定値に達するときの前記測定信号の供給電力をしきい値電力Ｐthとして求める段階と、
前記被測定物の代わりに基準受信アンテナを用い、該基準受信アンテナの受信電力が最大となるように、前記送信アンテナと基準受信アンテナの位置を調整したときの前記送信アンテナへの信号供給電力Ｐc′と受信最大電力Ｐr′を求める段階とを含み、
前記求めた各電力値Ｐth、Ｐc′、Ｐr′と、前記被測定物を測定したときの前記送信アンテナの反射係数Γ、前記基準受信アンテナを測定したときの前記送信アンテナの反射係数Γ′、前記基準受信アンテナの既知の放射効率ηr′、前記被測定物の自由空間中における既知の不整合損失Ｌｍとを用い、次式、
ＴＩＳ
＝［Ｐth（１−｜Γ｜ ^２）Ｐr′］／［Ｐc′（１−｜Γ′｜ ^２）ηr′・Ｌｍ］
にしたがって被測定物のＴＩＳを算出することを特徴とする。 In order to achieve the above object, the TIS measurement method according to claim 1 of the present invention comprises:
A transmission antenna (3) is arranged in the vicinity of one focal point in a closed space surrounded by a metal wall surface and is obtained by rotating an ellipse around an axis passing through the two focal points, and in the vicinity of the other focal point Arranging the device under test (1) and adjusting the positions of the transmission antenna and the device under test so that the signal output from the transmission antenna is received at the device under maximum sensitivity;
A measurement signal for measuring a bit error rate that can be received by the device under test is supplied to the transmitting antenna, and a bit error rate of a demodulated data signal of the device under test that has received the measurement signal can be measured. Changing the supply power of the measurement signal to determine the supply power of the measurement signal when the bit error rate reaches a specified value as the threshold power Pth;
A signal receiving power Pc to the transmitting antenna when the position of the transmitting antenna and the reference receiving antenna is adjusted so that the receiving power of the reference receiving antenna is maximized by using a reference receiving antenna instead of the device under test. And determining the maximum received power Pr ′,
Each of the obtained power values Pth, Pc ′, Pr ′, the reflection coefficient Γ of the transmitting antenna when the object to be measured is measured, the reflection coefficient Γ ′ of the transmitting antenna when the reference receiving antenna is measured, Using the known radiation efficiency ηr ′ of the reference receiving antenna and the known mismatch loss Lm in the free space of the device under test,
TIS
= [Pth (1- | Γ | ² ) Pr ′] / [Pc ′ (1- | Γ ′ | ² ) ηr ′ · Lm]
The TIS of the object to be measured is calculated according to

また、本発明の請求項２のＴＩＳ測定装置は、
楕円をその２つの焦点を通る軸を中心に回転して得られる楕円球状で、金属の壁面で囲まれた閉空間を有し、送信アンテナ３を一方の焦点の近傍位置に支持し、被測定物（１）を他方の焦点の近傍位置に支持する支持手段（５０、５５）を含む結合器（２１）と、
前記送信アンテナに前記被測定物が受信可能な測定信号を供給する送信機（２）と、
前記測定信号を受信した被測定物の復調データを受けて、そのビット誤り率を測定するビット誤り率測定器（５）と、
前記送信アンテナから出力された信号が前記被測定物に最大感度で受信されるように前記送信アンテナと前記被測定物の位置が調整された状態で、前記送信機が供給する測定信号の電力を変化させて、前記ビット誤り率測定器によって測定されるビット誤り率が規定値に達したときの供給電力をしきい値電力Ｐthとして求めるしきい値電力測定手段（１９１）と、
前記被測定物の代わりに基準受信アンテナを用い、該基準受信アンテナの受信電力が最大となるように、前記送信アンテナと基準受信アンテナの位置を調整したときの前記送信機の信号供給電力Ｐc′と受信最大電力Ｐr′を予め記憶する手段と、
前記しきい値電力Ｐth、信号供給電力Ｐc′、受信最大電力Ｐr′、前記被測定物を測定したときの前記送信アンテナの反射係数Γ、前記基準受信アンテナを測定したときの前記送信アンテナの反射係数Γ′、前記基準受信アンテナの既知の放射効率ηr′、前記被測定物の自由空間中における既知の不整合損失Ｌｍとを用い、次式、
ＴＩＳ
＝［Ｐth（１−｜Γ｜ ^２）Ｐr′］／［Ｐc′（１−｜Γ′｜ ^２）ηr′・Ｌｍ］
にしたがって、被測定物のＴＩＳを算出するＴＩＳ算出手段（１９２）とを有していることを特徴とする。 Moreover, the TIS measuring apparatus according to claim 2 of the present invention is:
An ellipsoid obtained by rotating an ellipse around an axis passing through its two focal points, has a closed space surrounded by metal walls, supports the transmitting antenna 3 at a position near one focal point, and is measured A coupler (21) comprising support means (50, 55) for supporting the object (1) in the vicinity of the other focal point;
A transmitter (2) for supplying a measurement signal receivable by the device under test to the transmission antenna;
A bit error rate measuring device (5) for receiving the demodulated data of the device under test that has received the measurement signal and measuring the bit error rate;
The power of the measurement signal supplied by the transmitter is adjusted while the positions of the transmission antenna and the device under test are adjusted so that the signal output from the transmission antenna is received by the device under test with maximum sensitivity. A threshold power measuring means (191) for changing the bit error rate measured by the bit error rate measuring device to obtain a supply power as a threshold power Pth when the bit error rate reaches a specified value;
A signal receiving power Pc ′ of the transmitter when the position of the transmitting antenna and the reference receiving antenna is adjusted so that the receiving power of the reference receiving antenna is maximized by using a reference receiving antenna instead of the DUT. And means for storing the received maximum power Pr ′ in advance,
The threshold power Pth, the signal supply power Pc ′, the received maximum power Pr ′, the reflection coefficient Γ of the transmitting antenna when the object to be measured is measured, and the reflection of the transmitting antenna when the reference receiving antenna is measured Using the coefficient Γ ′, the known radiation efficiency ηr ′ of the reference receiving antenna, and the known mismatch loss Lm in the free space of the DUT,
TIS
= [Pth (1- | Γ | ² ) Pr ′] / [Pc ′ (1- | Γ ′ | ² ) ηr ′ · Lm]
And TIS calculating means (192) for calculating the TIS of the object to be measured.

このように、本発明は、楕円球の閉空間の一方の焦点に配置した送信アンテナから放射した電波を、他方の焦点に配置した被測定物に対してほぼ全方向から同位相で集約させて、全空間からの電波を積分したのと同等な状態にして、ビット誤り率が規定値となる時のしきい値電力を求め、そのしきい値電力と、被測定物に代わって基準受信アンテナを配置したときに得られる電力値および送信アンテナと基準受信アンテナについての既知のパラメータとから、被測定物のＴＩＳを算出しているので、従来の３次元積分方式に比べて格段に短時間にＴＩＳを測定することができる。 In this way, the present invention aggregates radio waves radiated from the transmitting antenna arranged at one focus of the closed space of the elliptical sphere with the same phase from almost all directions with respect to the object to be measured arranged at the other focus. , Obtain the threshold power when the bit error rate reaches the specified value in a state equivalent to the integration of radio waves from the entire space, and use the threshold power and the reference receiving antenna instead of the device under test Since the TIS of the device under test is calculated from the power value obtained when the signal is placed and the known parameters of the transmitting antenna and the reference receiving antenna, the time is much shorter than the conventional three-dimensional integration method. TIS can be measured.

本発明のＴＩＳ測定方法を説明するための測定系の構成図Configuration diagram of a measurement system for explaining the TIS measurement method of the present invention 本発明のＴＩＳ測定方法を説明するための校正系の構成図Configuration diagram of calibration system for explaining the TIS measurement method of the present invention 本発明のＴＩＳ測定方法の手順の一例を示すフローチャートThe flowchart which shows an example of the procedure of the TIS measuring method of this invention 本発明のＴＩＳ測定装置の実施形態の構成図Configuration diagram of an embodiment of a TIS measuring apparatus of the present invention 要部の内部構造を示す図Diagram showing the internal structure of the main part 要部の内部構造を示す図Diagram showing the internal structure of the main part 要部の内部構造を示す図Diagram showing the internal structure of the main part ＴＩＳの定義を説明するための図Illustration for explaining the definition of TIS

以下、図面に基づいて本発明の実施の形態を説明する。
始めに本発明のＴＩＳの測定原理について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the measurement principle of the TIS of the present invention will be described.

前記したＴＩＳの式（３）の分母は、ゲインを用いて表すと、
（１／Ｐｓ）∫∫（Ｇ_θ＋Ｇ_φ）sinθdθdφ……（４）
となる。 The denominator of the above TIS equation (3) is expressed using gain.
(1 / Ps) ∫∫ (G _θ + G _φ ) sinθdθdφ (4)
It becomes.

ここで、携帯端末などの被測定物の内部の受信アンテナの効率をηr 、その受信アンテナと受信部の間の自由空間中における不整合損失をＬｍ、指向性利得をＧ_Ｄθ（θ,φ）、Ｇ_Ｄφ（θ,φ）とすると、次式（５）が成立する。なお、前記したように、θとφの関数であることを示す（θ,φ）の記載は省略する。 Here, the efficiency of the receiving antenna inside the device under test such as a portable terminal is ηr, the mismatch loss in the free space between the receiving antenna and the receiving unit is Lm, and the directivity gain is G _Dθ (θ, φ). , G _Dφ (θ, φ), the following equation (5) is established. As described above, the description of (θ, φ) indicating that it is a function of θ and φ is omitted.

Ｇ_θ＋Ｇ_φ＝ηr ・Ｌｍ(Ｇ_Ｄθ＋Ｇ_Ｄφ) ……（５） _{_{G θ + G φ = ηr ·}} Lm (G Dθ + G Dφ) ...... (5)

また、指向性利得については、
∫∫(Ｇ_Ｄθ＋Ｇ_Ｄφ)sinθdθdφ＝４π ……（６）
が成立する。 For directivity gain,
_∫∫ (G _Dθ + G _Dφ ) sinθdθdφ = 4π (6)
Is established.

したがって、式（４）は、
（１／Ｐｓ）∫∫（Ｇ_θ＋Ｇ_φ）sinθdθdφ
＝（１／Ｐｓ）ηr ・Ｌｍ∫∫(Ｇ_Ｄθ＋Ｇ_Ｄφ) sinθdθdφ
＝（１／Ｐｓ）ηr ・Ｌｍ・４π
となり、これを式（３）に代入すれば、
ＴＩＳ＝Ｐｓ／（ηr ・Ｌｍ） ……（７）
が得られる。 Therefore, equation (4) becomes
(1 / Ps) ∫∫ (G _θ + G _φ ) sinθdθdφ
= (1 / Ps) ηr · Lm∫∫ (G _Dθ + G _Dφ ) sinθdθdφ
= (1 / Ps) ηr · Lm · 4π
And substituting this into equation (3) gives
TIS = Ps / (ηr · Lm) (7)
Is obtained.

上式（７）において、被測定物の自由空間中における不整合損失Ｌｍを既知とすると、ＴＩＳの測定は、被測定物の受信アンテナの放射効率ηrを測定することで得られ、その放射効率ηr は、後述する楕円球型の結合器を用いることで短時間に測定することができる。 In the above equation (7), assuming that the mismatch loss Lm in the free space of the device under test is known, the TIS measurement is obtained by measuring the radiation efficiency ηr of the receiving antenna of the device under test. ηr can be measured in a short time by using an ellipsoidal coupler described later.

次に、楕円球型の結合器を用いてＴＩＳを測定する方法について説明する。
図１は測定系を示す図であり、結合器２１は、楕円をその長軸を中心に回転させて得られる楕円球状の閉空間１２を囲む壁面１１をもち、その壁面１１が電磁波を反射する金属によって形成されている。 Next, a method for measuring TIS using an ellipsoidal coupler will be described.
FIG. 1 is a diagram showing a measurement system. A coupler 21 has a wall surface 11 surrounding an oval spherical closed space 12 obtained by rotating an ellipse around its major axis, and the wall surface 11 reflects electromagnetic waves. It is made of metal.

この結合器２１は、それを形成する楕円の一方の焦点Ｆ１から放射されて内壁で反射した電波が、同一長の経路を経て他方の焦点Ｆ２に集まるという楕円の幾何学的性質を用いたものであり、焦点位置からみて全方位からの電波がほぼ同位相で集約される、つまり全方位からの電波が積分された状態を模擬することができる。 This coupler 21 uses an elliptical geometric property that radio waves radiated from one focal point F1 of the ellipse forming it and reflected by the inner wall gather at the other focal point F2 via the same length path. Thus, it is possible to simulate a state in which radio waves from all directions are aggregated in substantially the same phase as viewed from the focal position, that is, radio waves from all directions are integrated.

図１に示した測定系の場合、ビット誤り率（以下、ＢＥＲと記す）を測定するためにデータ信号で変調された測定信号を送信機２から結合器２１の一方の焦点Ｆ１に放射中心をもつ送信アンテナ３にケーブルを介して供給する。このとき送信側の反射係数Γ（被測定物１を測定する場合の反射係数）は既知とする（予め測定しておく）。 In the case of the measurement system shown in FIG. 1, a measurement signal modulated with a data signal to measure a bit error rate (hereinafter referred to as BER) is transmitted from the transmitter 2 to one focal point F1 of the coupler 21. It supplies to the transmitting antenna 3 which has it via a cable. At this time, the reflection coefficient Γ on the transmission side (reflection coefficient when measuring the DUT 1) is assumed to be known (measured in advance).

また、結合器２１の他方の焦点Ｆ２には、携帯端末のような被測定物１のアンテナ部分を位置させ、その受信信号出力を結合器外部のＢＥＲ測定器５にケーブルを介して入力する。 Further, the antenna portion of the device under test 1 such as a portable terminal is positioned at the other focal point F2 of the coupler 21, and the received signal output is input to the BER measuring instrument 5 outside the coupler via a cable.

ここで、予め送信アンテナ３と被測定物１の位置を例えば楕円軸に沿って微調整して、感度最大となるようにしてから、送信機２から測定信号を供給しＢＥＲ測定を行う。 Here, after finely adjusting the positions of the transmission antenna 3 and the DUT 1 in advance along, for example, the elliptical axis so as to maximize the sensitivity, a measurement signal is supplied from the transmitter 2 to perform BER measurement.

そして、測定信号の供給電力を下げていき、ＢＥＲが規定値に達した時の電力をしきい値電力Ｐthとして求める。 Then, the supply power of the measurement signal is lowered, and the power when the BER reaches the specified value is obtained as the threshold power Pth.

このしきい値電力Ｐthと受信電力Ｐｓとの関係は、次のように表される。
Ｐth・Ｌc・ηt ・Ｌｍ・（１−｜Γ｜^２）Ｃ・ηr ＝Ｐｓ ……（８）
ここで、Ｌｃは送信側ケーブル損失、ηt は送信アンテナ効率、Ｃは結合器損失であり、これらは後述の校正系と共通に用いられるパラメータで、演算により除去されるため、既知である必要はない。また、ηr
は被測定物のアンテナ放射効率である。 The relationship between the threshold power Pth and the received power Ps is expressed as follows.
Pth · Lc · ηt · Lm · (1− | Γ | ² ) C · ηr = Ps (8)
Here, Lc is the transmission-side cable loss, ηt is the transmission antenna efficiency, and C is the coupler loss. These are parameters used in common with the calibration system described later, and are eliminated by calculation. Absent. Ηr
Is the antenna radiation efficiency of the device under test.

一方、図２に示す校正系では、送信機２から電力Ｐc′の無変調のキャリア信号を送信アンテナ３に供給し、その出力を基準受信アンテナ６で受信し、その受信電力を電力測定器７によって測定する。なお、このシステムではデータ変調の必要がないので送信機２の代わりにＳＧを用いることもできる。 On the other hand, in the calibration system shown in FIG. 2, an unmodulated carrier signal with power Pc ′ is supplied from the transmitter 2 to the transmission antenna 3, and its output is received by the reference reception antenna 6. Measure by. Since this system does not require data modulation, SG can be used instead of the transmitter 2.

この校正系では、送信アンテナ３と基準受信アンテナ６の位置を、例えば楕円軸の中心に対して対称に軸に沿って移動させて最大受信電力Ｐr′となるように設定する。 In this calibration system, the positions of the transmitting antenna 3 and the reference receiving antenna 6 are set to be the maximum received power Pr ′ by moving along the axis symmetrically with respect to the center of the elliptical axis, for example.

この状態で、送信電力Ｐc′と最大受信電力Ｐr′との間には次の関係が成立する。
Ｐc′・Ｌc・ηt
・（１−｜Γ′｜^２）Ｃ・ηr′＝Ｐr′ ……（９）
ここで、Γ′は基準受信アンテナ６を測定する場合の送信側の反射係数、ηr′は基準受信アンテナ６の放射効率であり、共に既知とする。 In this state, the following relationship is established between the transmission power P c ′ and the maximum reception power P r ′.
Pc '・ Lc ・ ηt
・ (1- | Γ ′ | ² ) C · ηr ′ = Pr ′ (9)
Here, Γ ′ is the reflection coefficient on the transmission side when measuring the reference receiving antenna 6, and ηr ′ is the radiation efficiency of the reference receiving antenna 6, both of which are known.

式（８）、（９）の除算により、次の結果が得られる。
ＴＩＳ
＝Ｐｓ／（ηr ・Ｌｍ）
＝［Ｐth（１−｜Γ｜^２）Ｐr′］／［Ｐc′（１−｜Γ′｜^２）ηr′・Ｌｍ］
……（１０） The following results are obtained by dividing the equations (8) and (9).
TIS
= Ps / (ηr · Lm)
= [Pth (1- | Γ | ² ) Pr ′] / [Pc ′ (1- | Γ ′ | ² ) ηr ′ · Lm]
...... (10)

このように、被測定物１のＴＩＳは、式（１０）の各既知の値により算出することができる。 As described above, the TIS of the DUT 1 can be calculated from each known value of the equation (10).

つまり、図３のフローチャートに示すように、楕円球型の結合器２１を用いた測定系で、予め、一定の送信電力において受信電力が最大となるように送信アンテナ３と被測定物１の位置の微調整を行う（Ｓ１、Ｓ２）。なお、この受信電力が最大になることについての把握は、例えば被測定物１の受信信号レベルを示すデータの出力機能を用いたり、あるいは送信電力の増減変化に追従してＢＥＲの値が変化するような比較的低い送信電力に設定し、ＢＥＲが最小となる（即ち受信電力最大となる）ように位置調整を行う方法が考えられる。 That is, as shown in the flowchart of FIG. 3, in the measurement system using the elliptical spherical coupler 21, the positions of the transmission antenna 3 and the device under test 1 are set so that the reception power becomes maximum at a predetermined transmission power in advance. Are finely adjusted (S1, S2). In order to grasp that the received power is maximized, for example, a data output function indicating the received signal level of the device under test 1 is used, or the BER value changes following an increase / decrease in transmission power. A method of adjusting the position so that the BER is minimized (that is, the reception power is maximized) can be considered by setting the transmission power to a relatively low value.

上記位置の微調整の後、ＢＥＲを監視しながら測定信号の供給電力を下げ、ＢＥＲが規定値となった時のしきい値電力Ｐthを求めて記憶する（Ｓ３〜Ｓ５）。 After fine adjustment of the position, the supply power of the measurement signal is lowered while monitoring the BER, and the threshold power Pth when the BER becomes a specified value is obtained and stored (S3 to S5).

そして、前記した校正系にセットして、送信側の供給電力をＰc′とし、送信アンテナ３と基準受信アンテナ６の位置を微調整して、受信電力を最大Ｐr′とする（Ｓ６、Ｓ７）。 Then, it is set in the calibration system described above, the supply power on the transmission side is set to Pc ′, the positions of the transmission antenna 3 and the reference reception antenna 6 are finely adjusted, and the reception power is set to the maximum Pr ′ (S6, S7). .

上記処理により、式（１０）の演算に必要な各電力値Ｐth、Ｐc′、Ｐr′が実測され、その他のパラメータ（Γ、Γ′、ηr′、Ｌｍ）が既知となっていれば、被測定物１のＴＩＳを算出することができる（Ｓ８）。 By the above processing, the electric power values Pth, Pc ′, Pr ′ necessary for the calculation of Expression (10) are actually measured, and if other parameters (Γ, Γ ′, ηr ′, Lm) are known, The TIS of the measurement object 1 can be calculated (S8).

なお、上記処理のうち校正系の処理Ｓ６、Ｓ７は、使用する送信アンテナ３、基準受信アンテナ６等の構成要素に変化がなければいつ行ってもよく、その結果得られた送信電力Ｐc′と受信最大電力Ｐr′をメモリ（図示せず）に記憶しておき、測定系で得られた電力値とともに用いてＴＩＳを算出すればよい。 Of the above-described processes, the calibration processes S6 and S7 may be performed whenever there is no change in the components such as the transmitting antenna 3 and the reference receiving antenna 6 to be used. The received maximum power Pr ′ may be stored in a memory (not shown) and used together with the power value obtained by the measurement system to calculate TIS.

次に、上記方法を用いたＴＩＳ測定装置の実施形態を説明する。 Next, an embodiment of a TIS measuring apparatus using the above method will be described.

図４は、上記測定方法に基づいたＴＩＳ測定装置２０の全体構成を示している。
このＴＩＳ測定装置２０は、前記した結合器２１、送信機２、送信アンテナ３、ＢＥＲ測定器５、測定定制御部１９０を有している。なお、ここでは、校正系で得られたデータは測定定制御部１９０に予め記憶されているものとする。 FIG. 4 shows the overall configuration of the TIS measurement apparatus 20 based on the measurement method.
The TIS measuring apparatus 20 includes the coupler 21, the transmitter 2, the transmitting antenna 3, the BER measuring device 5, and the measurement constant control unit 190. Here, it is assumed that data obtained by the calibration system is stored in advance in the measurement constant control unit 190.

結合器２１には、楕円球状の閉空間１２を囲む壁面１１と、その閉空間１２内の一方の焦点Ｆ１の位置に送信アンテナ１１のほぼ放射中心位置がくるように支持する手段と、他方の焦点Ｆ２の位置に被測定物１のアンテナ部（あるいは前記した基準受信アンテナ６）の放射中心がくるように支持する手段とが設けられている。また、被測定物１、受信基準アンテナ６の出し入れができるように、閉空間１２を開閉できる構造が必要である。 The coupler 21 includes a wall surface 11 surrounding the oval closed space 12, means for supporting the transmitting antenna 11 so that the radiation center position is substantially at the position of one focal point F 1 in the closed space 12, and the other. Means for supporting the radiation center of the antenna portion (or the above-described reference receiving antenna 6) of the DUT 1 at the position of the focal point F2 is provided. Further, a structure capable of opening and closing the closed space 12 is required so that the DUT 1 and the reception reference antenna 6 can be taken in and out.

図５〜図７は、その具体例を示すものであり、結合器２１は、下ケース２２と上ケース２３とに別れた開閉式で、下ケース２２の上板２２ａには、楕円状の穴（図示せず）が形成され、その穴に前記した楕円球状の閉空間１２の下半部の外周形状に沿った形状の内壁２５ａを有する第１の内壁形成体２５が取り付けられている。 5 to 7 show specific examples thereof. The coupler 21 is an open / close type separated into a lower case 22 and an upper case 23, and an upper hole 22a of the lower case 22 has an elliptical hole. (Not shown) is formed, and a first inner wall forming body 25 having an inner wall 25a having a shape along the outer peripheral shape of the lower half of the oval spherical closed space 12 is attached to the hole.

第１の内壁形成体２５は、電波を反射する金属板、金属メッシュ板のプレス加工、あるいは合成樹脂の成形品の内壁に金属膜を設ける等して形成され、その上縁には、僅かに外側へ延びて前記穴の外縁と重なるフランジ２６が延設されており、この第１の内壁形成体２５は、フランジ２６部分が下ケース２２の上板２２ａに固定されている。 The first inner wall forming body 25 is formed by pressing a metal plate that reflects radio waves, pressing a metal mesh plate, or providing a metal film on the inner wall of a synthetic resin molded product. A flange 26 that extends outward and overlaps with the outer edge of the hole is extended, and the flange portion of the first inner wall forming body 25 is fixed to the upper plate 22 a of the lower case 22.

一方、上ケース２３の下板２３ａにも、楕円形の穴（図示せず）が設けられ、この穴に、第２の内壁形成体３０が装着されている。 On the other hand, the lower plate 23a of the upper case 23 is also provided with an oval hole (not shown), and the second inner wall forming body 30 is mounted in this hole.

第２の内壁形成体３０は、第１の内壁形成体２５と対称な形状を有している。即ち、前記した楕円球状の閉空間１２の上半部の外周形状に沿った形状の内壁３０ａを有し、その開口側の縁部には、僅かに外側へ延びて上ケース２３の前記穴の外縁と重なるフランジ３１が延設され、このフランジ３１部分が下板２３ａに固定されている。 The second inner wall forming body 30 has a symmetric shape with the first inner wall forming body 25. That is, the inner wall 30a has a shape along the outer peripheral shape of the upper half of the oval spherical closed space 12 described above, and the opening side edge extends slightly outward to form the hole of the upper case 23. A flange 31 that overlaps the outer edge is extended, and the flange 31 portion is fixed to the lower plate 23a.

上ケース２３は、下ケース２２に対して図示しないヒンジ機構とロック機構などにより開閉自在に連結されており、上ケース２３を下ケース２２に重なるように閉じてロックしたとき、図５のように、第１の内壁形成体２５のフランジ２６と第２の内壁形成体３０のフランジ３１が全体的に隙間なく面接触して、それぞれの内壁２５ａ、３０ａが連続して、前記した壁面１１で囲まれた楕円球状の閉空間１２が形成される。 The upper case 23 is connected to the lower case 22 by a hinge mechanism and a lock mechanism (not shown) so as to be freely opened and closed. When the upper case 23 is closed and locked so as to overlap the lower case 22, as shown in FIG. The flange 26 of the first inner wall forming body 25 and the flange 31 of the second inner wall forming body 30 are in surface contact with each other without any gap, and the inner walls 25a, 30a are continuously surrounded by the wall surface 11 described above. A closed elliptical closed space 12 is formed.

なお、下ケース２２と上ケース２３には、閉じたときに、上下の内壁形成体２５、３０がずれない状態で重なり合うようにするための位置決め機構（例えば図のようにガイドピン４０とそれを受け入れるガイド穴４１）が形成されている。 The lower case 22 and the upper case 23 are provided with a positioning mechanism (for example, a guide pin 40 and the guide pin 40 as shown in the figure) so that the upper and lower inner wall forming bodies 25 and 30 overlap when they are closed. A receiving guide hole 41) is formed.

また、例えば、図６の（ａ）のように、一方の内壁形成体３０の開口側の内縁のほぼ全周に渡って弾性リブ４５を突設させることで、図６の（ｂ）のように他方の内壁形成体２５と合わせられたときに、その弾性リブ４５を内壁形成体２５の開口側の内縁全周に接触させて、内壁形成体２５、３０のフランジ２６、３１の接触部を覆い、その接触部に隙間が生じた場合の電波の漏洩等などを低減することができる。 Further, for example, as shown in FIG. 6A, an elastic rib 45 is provided so as to protrude over substantially the entire circumference of the inner edge on the opening side of one inner wall forming body 30 as shown in FIG. 6B. When the elastic ribs 45 are brought into contact with the entire inner edge of the inner wall forming body 25 on the opening side, the contact portions of the flanges 26 and 31 of the inner wall forming bodies 25 and 30 are brought into contact with each other. It is possible to reduce leakage of radio waves and the like when a gap is generated in the cover and the contact portion.

また、ここでは、下ケース２２の上板２２ａと第１の内壁形成体２５、上ケース２３の下板２３ａと第２の内壁形成板３０とがそれぞれ別体になっている例を示しているが、下ケース２２の上板２２ａと第１の内壁形成体２５、および上ケース２３の下板２３ａと第２の内壁形成板３０と上板２２とを同一材料で一体に形成してもよい。また、ここでは第１の内壁形成体２５および第２の内壁形成体３０の外周形状を半楕円外周形状にしているが、内壁２５ａ、３０ａが前記した楕円球に沿っていればよく、外側の形状は任意である。 Further, here, an example is shown in which the upper plate 22a of the lower case 22 and the first inner wall forming body 25, and the lower plate 23a of the upper case 23 and the second inner wall forming plate 30 are separated from each other. However, the upper plate 22a and the first inner wall forming body 25 of the lower case 22 and the lower plate 23a, the second inner wall forming plate 30 and the upper plate 22 of the upper case 23 may be integrally formed of the same material. . Further, here, the outer peripheral shape of the first inner wall forming body 25 and the second inner wall forming body 30 is a semi-elliptical outer peripheral shape, but the inner walls 25a and 30a may be along the elliptical sphere described above, The shape is arbitrary.

図４、図５、図７に示しているように、第１の内壁形成体２５の開口面上の前記焦点Ｆ１の近傍位置には、前記した閉空間１２内で送信アンテナ３を支持するための送信側支持部５０が設けられ、焦点Ｆ２の近傍位置には、被測定物１や基準受信アンテナ６を支持するための受信側支持部５５が設けられている。 As shown in FIGS. 4, 5, and 7, the transmitting antenna 3 is supported in the closed space 12 at a position near the focal point F <b> 1 on the opening surface of the first inner wall forming body 25. The transmission side support part 50 is provided, and the reception side support part 55 for supporting the DUT 1 and the reference reception antenna 6 is provided in the vicinity of the focal point F2.

送信側支持部５０は、送信アンテナ３の放射中心が焦点Ｆ１の位置にほぼ一致する状態を基準位置とし、それらを焦点Ｆ１、Ｆ２を結ぶ軸に沿って一定距離（例えば中心波長λに対して±λ／４）移動できる状態で支持するものであり、焦点Ｆ１、Ｆ２を結ぶ軸に沿って移動可能で送信アンテナ３を支持する支持板５１と、支持板５１の下降を防ぐ基台５３および後述するスライド駆動装置１８０により構成されている。なお、これらの各構成部材のうち、結合器２１内部に配置されたものは、電波に対する透過率が高い（比誘電率が１に近い）合成樹脂材により形成されている。 The transmission-side support unit 50 uses a state in which the radiation center of the transmission antenna 3 substantially coincides with the position of the focal point F1 as a reference position, and makes them a fixed distance (for example, with respect to the central wavelength λ) along the axis connecting the focal points F1 and F2. ± λ / 4) is supported in a movable state, is movable along an axis connecting the focal points F1 and F2, is supported by a support plate 51 that supports the transmission antenna 3, a base 53 that prevents the support plate 51 from descending, and It is comprised by the slide drive device 180 mentioned later. Of these constituent members, those arranged inside the coupler 21 are made of a synthetic resin material having high radio wave transmittance (relative dielectric constant close to 1).

この支持板５１の外側端部には内壁形成体２５を貫通摺動する軸部５１ａが突設され、その軸部５１ａは、内壁形成体２５の外側に固定されたスライド移動装置１８０に保持されている。 A shaft portion 51 a that slides through the inner wall forming body 25 protrudes from the outer end portion of the support plate 51, and the shaft portion 51 a is held by a slide moving device 180 that is fixed to the outside of the inner wall forming body 25. ing.

スライド移動装置１８０は、例えば断面凹状に形成され、その中央の溝部で支持板５１の軸部５１ａを摺動自在に保持でき、内部に設けられた駆動源（例えばモータ）の駆動制御により、支持板５１を軸に沿った方向にスライド移動させる。 The slide moving device 180 is formed, for example, in a concave shape in cross section, and can hold the shaft portion 51a of the support plate 51 slidably in the central groove portion, and is supported by drive control of a drive source (for example, a motor) provided therein. The plate 51 is slid in the direction along the axis.

なお、信号給電用の同軸ケーブル１６２は、例えば支持板５１の軸部５１ａの内部に貫通する穴を通過している。 Note that the signal-feeding coaxial cable 162 passes through, for example, a hole penetrating into the shaft portion 51 a of the support plate 51.

また、受信側支持部５５も送信側支持部５１と同様に、電波に対する透過率が高い合成樹脂材により形成された支持板５６と、支持板５６の下降を防ぐ基台５７、支持板５６の上に被測定物１や基準受信アンテナ６を固定する固定具５８およびスライド移動装置１８１により構成されている。固定具５８は、例えば電波伝搬に影響を与えない伸縮自在なバンドで、被測定物１や基準受信アンテナ６を支持板５６の上の所定位置に固定させる。 Similarly to the transmission side support unit 51, the reception side support unit 55 includes a support plate 56 made of a synthetic resin material having a high transmittance to radio waves, a base plate 57 that prevents the support plate 56 from descending, and a support plate 56. A fixture 58 for fixing the DUT 1 and the reference receiving antenna 6 and a slide moving device 181 are configured on the top. The fixture 58 is, for example, a stretchable band that does not affect radio wave propagation, and fixes the DUT 1 and the reference receiving antenna 6 to a predetermined position on the support plate 56.

この支持板５６にも、その外側端部に内壁形成体２５を貫通摺動する軸部５６ａが突設され、その軸部５６ａは、内壁形成体２５の外側に固定されたスライド移動装置１８１に係合保持されている。 The support plate 56 is also provided with a shaft portion 56a projecting and sliding through the inner wall forming body 25 at the outer end thereof, and the shaft portion 56a is attached to a slide moving device 181 fixed to the outside of the inner wall forming body 25. Engagement is held.

スライド移動装置１８１は、スライド移動装置１８１と同様に構成され、断面凹状に形成されていて、その中央の溝部で支持板５６の軸部５６ａを摺動自在に保持でき、内部に設けられた駆動源（例えばモータ）の駆動制御により、支持板５６を軸に沿った方向にスライド移動させる。 The slide moving device 181 is configured in the same manner as the slide moving device 181 and has a concave cross section. The shaft portion 56a of the support plate 56 can be slidably held by a groove in the center of the slide moving device 181. The support plate 56 is slid in a direction along the axis by driving control of a source (for example, a motor).

なお、ここでは、二つのスライド移動装置１８０、１８１によってアンテナ間隔を連続的に変化できるようになっているが、例えば、λ／８ステップで離散的に変化させてもよく、自動制御だけでなく手動で位置を変えられるようにしてもよい。 Here, although the antenna interval can be continuously changed by the two slide moving devices 180 and 181, for example, it may be changed discretely in λ / 8 steps, and not only automatic control. The position may be changed manually.

また、受信側支持部５５においても、被測定物１の信号出力コードや基準受信アンテナ６のケーブルを外部に引き出すことができるように例えば支持板５６の軸部５６ａの内部に貫通する穴が形成されている。 Also, in the receiving side support portion 55, for example, a hole penetrating inside the shaft portion 56a of the support plate 56 is formed so that the signal output code of the DUT 1 and the cable of the reference receiving antenna 6 can be pulled out. Has been.

この被測定物１の出力信号は、ケーブル１６を介して結合器２１の外部に出力され、ＢＥＲ測定器５に接続される。 The output signal of the device under test 1 is output to the outside of the coupler 21 via the cable 16 and connected to the BER measuring device 5.

そして、測定制御部１９０は、測定系において、送信機２の出力レベルを制御し、ＢＥＲの値を監視し、しきい値電力Ｐthを求め、予め校正系で得られている他の電力値Ｐc′、Ｐr′と、既知のパラメータ（Γ、Γ′、ηr′、Ｌｍ）とに基づいて、式（１０）にしたがって被測定物１のＴＩＳを算出する。 Then, the measurement control unit 190 controls the output level of the transmitter 2 in the measurement system, monitors the BER value, obtains the threshold power Pth, and obtains another power value Pc obtained in advance in the calibration system. Based on ', Pr' and the known parameters (Γ, Γ ', ηr', Lm), the TIS of the DUT 1 is calculated according to the equation (10).

より具体的にいえば、測定制御部１９０は、図４に示しているように、しきい値電力測定手段１９１およびＴＩＳ算出手段１９２を有している。 More specifically, the measurement control unit 190 includes a threshold power measurement unit 191 and a TIS calculation unit 192 as shown in FIG.

前記図３のフローチャートに示したように、しきい値電力測定手段１９１は、測定系において、スライド移動装置１８０、１８１の制御で位置調整を行ってから、ＢＥＲが規定値となる測定信号のしきい値電力Ｐthを求める。 As shown in the flowchart of FIG. 3, the threshold power measuring means 191 performs the adjustment of the measurement signal at which the BER becomes a specified value after adjusting the position by the control of the slide movement devices 180 and 181 in the measurement system. The threshold power Pth is obtained.

また、ＴＩＳ算出手段１９２は、その測定されたしきい値電力Ｐthと、他の電力値を含む既知のパラメータを用いて式（１０）にしたがって、ＴＩＳを算出する。 The TIS calculation means 192 calculates the TIS according to the equation (10) using the measured threshold power Pth and known parameters including other power values.

なお、図３のフローチャートの校正系の処理（Ｓ６、Ｓ７）も、測定制御部１９０が自動で行うようにしてもよい。 Note that the calibration control process (S6, S7) in the flowchart of FIG. 3 may also be automatically performed by the measurement control unit 190.

このように実施形態のＴＩＳ測定装置２０は、楕円球型の結合器２１を用い、その一方の焦点位置から放射された電波を他方の焦点位置に集合させてあたかも全方位について電波を積分した状態と同等にして得られたしきい値電力に基づいて、被測定物のＴＩＳを求めているので、従来のような３Ｄ積分方式に比べて格段に短時間にＴＩＳを求めることができる。 As described above, the TIS measuring apparatus 20 according to the embodiment uses the ellipsoidal coupler 21 and collects radio waves radiated from one focal position at the other focal position, as if the radio waves were integrated in all directions. Since the TIS of the object to be measured is obtained based on the threshold power obtained in the same manner as in the above, the TIS can be obtained in a much shorter time than the conventional 3D integration method.

１……被測定物、２……送信機、３……送信アンテナ、５……ＢＥＲ測定器、６……基準受信アンテナ、７……電力測定器、１１……壁面、１２……閉空間、２０……ＴＩＳ測定装置、２１……結合器、２２……下ケース、２３……上ケース、２５……第１の内壁形成体、２６……フランジ、３０……第２の内壁形成体、５０……送信側支持部、５５……受信側支持部、１００……送信機、１１０……受信機、１１１……受信アンテナ、１８０、１８１……スライド移動装置、１９０……測定制御部、１９１……しきい値電力測定手段、１９２……ＴＩＳ算出手段 DESCRIPTION OF SYMBOLS 1 ... Object to be measured, 2 ... Transmitter, 3 ... Transmitting antenna, 5 ... BER measuring device, 6 ... Reference receiving antenna, 7 ... Power measuring device, 11 ... Wall surface, 12 ... Closed space , 20 ... TIS measuring device, 21 ... coupler, 22 ... lower case, 23 ... upper case, 25 ... first inner wall forming body, 26 ... flange, 30 ... second inner wall forming body , 50... Transmission side support, 55... Reception side support, 100... Transmitter, 110... Receiver, 111... Reception antenna, 180 and 181. 191 ... Threshold power measuring means, 192 ... TIS calculating means

Claims

A transmission antenna (3) is arranged in the vicinity of one focal point in a closed space surrounded by a metal wall surface and is obtained by rotating an ellipse around an axis passing through the two focal points, and in the vicinity of the other focal point Arranging the device under test (1) and adjusting the positions of the transmission antenna and the device under test so that the signal output from the transmission antenna is received at the device under maximum sensitivity;
A measurement signal for measuring a bit error rate that can be received by the device under test is supplied to the transmitting antenna, and a bit error rate of a demodulated data signal of the device under test that has received the measurement signal can be measured. Changing the supply power of the measurement signal to determine the supply power of the measurement signal when the bit error rate reaches a specified value as the threshold power Pth;
A signal receiving power Pc to the transmitting antenna when the position of the transmitting antenna and the reference receiving antenna is adjusted so that the receiving power of the reference receiving antenna is maximized by using a reference receiving antenna instead of the device under test. And determining the maximum received power Pr ′,
Each of the obtained power values Pth, Pc ′, Pr ′, the reflection coefficient Γ of the transmitting antenna when the object to be measured is measured, the reflection coefficient Γ ′ of the transmitting antenna when the reference receiving antenna is measured, Using the known radiation efficiency ηr ′ of the reference receiving antenna and the known mismatch loss Lm in the free space of the device under test,
TIS
= [Pth (1- | Γ | ² ) Pr ′] / [Pc ′ (1- | Γ ′ | ² ) ηr ′ · Lm]
The TIS measurement method characterized by calculating TIS of a to-be-measured object according to this .

An ellipsoid obtained by rotating an ellipse around an axis passing through its two focal points, has a closed space surrounded by metal walls, supports the transmitting antenna 3 at a position near one focal point, and is measured A coupler (21) comprising support means (50, 55) for supporting the object (1) in the vicinity of the other focal point;
A transmitter (2) for supplying a measurement signal receivable by the device under test to the transmission antenna;
A bit error rate measuring device (5) for receiving the demodulated data of the device under test that has received the measurement signal and measuring the bit error rate;
The power of the measurement signal supplied by the transmitter is adjusted while the positions of the transmission antenna and the device under test are adjusted so that the signal output from the transmission antenna is received by the device under test with maximum sensitivity. A threshold power measuring means (191) for changing the bit error rate measured by the bit error rate measuring device to obtain a supply power as a threshold power Pth when the bit error rate reaches a specified value;
A signal receiving power Pc ′ of the transmitter when the position of the transmitting antenna and the reference receiving antenna is adjusted so that the receiving power of the reference receiving antenna is maximized by using a reference receiving antenna instead of the DUT. And means for storing the received maximum power Pr ′ in advance,
The threshold power Pth, the signal supply power Pc ′, the received maximum power Pr ′, the reflection coefficient Γ of the transmitting antenna when the object to be measured is measured, and the reflection of the transmitting antenna when the reference receiving antenna is measured Using the coefficient Γ ′, the known radiation efficiency ηr ′ of the reference receiving antenna, and the known mismatch loss Lm in the free space of the DUT,
TIS
= [Pth (1- | Γ | ² ) Pr ′] / [Pc ′ (1- | Γ ′ | ² ) ηr ′ · Lm]
And a TIS calculating means (192) for calculating the TIS of the object to be measured .