近傍電磁界の遠方変換理論と計測評価システムの開発に関する研究

近傍電磁界の遠方変換理論と計測評価システムの開発に関する研究

小 林 弘 一

電子情報システム工学科 波動情報システム研究室

(2020 年 12月11 日受理)

Study on Theory of Electromagnetic Near-Field to Far-Field Transformation

and Development of Measurement Evaluation System

Hirokazu Kobayashi

Electromagnetic Information System Laboratory,

Department of Electronics and Information Systems Engineering

Abstract

_{In this study, we discuss the near-field to far-field transformation (NFFFT) theory for radar cross-section (RCS) of}

an electrically large object and antenna pattern, which is a comprehensive review of the author's published articles over

the past 10 years. When the electrical size of the object under test is large, the probe antenna that measures the scattered

waves from the object must be placed far away from the object to illuminate the plane electromagnetic wave that is the

measurement premise. Assuming that the measurement frequency is , this distance is generally evaluated by

ଶ

₍

_{, where : wavelength, : speed of light). If}

_{m and}

_{GHz, for example, then}

m, which is an unrealistic measurement condition. Therefore, it is conceivable to acquire the scattered

electromag-netic field near the object by some method and theoretically transform it into a far-region. At this time, when an antenna

is under test, the measurement system has one-way relationship of radiation to the antenna and output from the antenna,

and this expression can be strictly given by an integral equation. Conversely, since RCS measurement is two-way in

principle, it is very difficult to formulate these electromagnetic field relationships. However, if a radar image based on

the scattered waves from the object is obtained, it is considered that the far-field generated by the source can be evaluated

by regarding the image as a scattered wave source. Based on this concept, the relationship between the radar image of

the object to be evaluated and the three-dimensional RCS is constructed. The theoretical validity is proved through

numerical calculations and comparative examination using actual measurement data. Above all, it was also found that

the unnecessary waves environmentally caused by the anechoic chamber and the like can be suppressed by appropriately

treating the generated image including the unnecessary waves received at the time of measurement. From this

confirm-ative experiment, it was proved for the electromagnetic wave that the time-axis processing such as the fast Fourier

transform (FFT) and this spatial-axis processing in the image data are equivalent.

キーワード; 近傍電磁界, 遠方界変換

, レーダ断面積(RCS), レーダ画像, 逆合成開口レーダ(ISAR),

焦点化,

円周/円筒走査, アンテナ放射パターン

Keyword; Electromagnetic n

ear-field, far-field transformation, radar cross-section (RCS), radar imaging, inverse

syn-thetic aperture radar (ISAR), focusing, circular/cylindrical scanning, antenna radiation pattern.

Osaka Institute of Technology Vol. 65, No. 2（2020）pp. 31〜54

1.·͕͖͑ ిؾ௕ͷେ͖ͳ෺ମͷϨʔμஅ໘ੵ(radar cross-section: RCS)ΛैདྷͷԕํྖҬͰ௚઀ܭଌ͢Δͷ͸ɺ ࠔ೉Λ൐͏৔߹͕ଟ͍ɻরࣹ೾͕ฏ໘೾ͱΈͳ͞ΕΔ΄ Ͳे෼ԕํͰɺRCS͸ఆٛ͞ΕΔ͔ΒͰ͋Δɻ͜ͷڑ཭ ͷ໨҆͸෇࿥Ͱ΋ߟ࡯͍ͯ͠ΔΑ͏ʹɺD Λඃଌఆ෺ ମͷ࠷େੇ๏ɺλΛଌఆप೾਺ͷ೾௕ͱͯ͠2D2_/λͰ ༩͑ΒΕΔ[1]ɻ͜ͷΑ͏ͳঢ়گʹରͯ͠ɺओʹೋͭͷ ରࡦ͕࠾ΒΕ͍ͯΔɻҰͭ͸େ͖ͳύϥϘϥ൓ࣹڸͷ։ ޱྖҬͷҐ૬ͷଗͬͨి࣓ք಺ʹඃଌఆ෺Λ഑ஔ͢Δ ίϯύΫτϨϯδ๏Ͱ͋Γɺطʹ80೥୅ʹ͸RCS͓Α ͼΞϯςφܭଌͳͲʹ࣮༻Խ͞Ε͍ͯΔɻ΋͏Ұͭ͸ۙ ๣ྖҬͰͷి࣓քΛऔಘ͠ɺͦͷσʔλ͔Βԕํి࣓ք ΛٻΊΔۙ๣քԕํม׵๏(near-field to far-field transformation: NFFFT) Ͱ͋Δɻ͜Ε΋ίϯύΫτϨ ϯδ๏ͱಉ࣌ظʹΞϯςφܭଌ๏ͱͯ͠ݚڀ։ൃ͞Ε ͍͕ͯͨɺ2-wayܭଌͱͳΔRCSධՁʹ͸ద༻͕ࠔ೉Ͱ ͋ͬͨɻ͜ͷ໰୊ʹର͠ɺٯ߹੒։ޱϨʔμ(inverse

synthetic aperture radar: ISAR)ॲཧʹΑͬͯಘΒΕ

ͨϨʔμը૾͔ΒԕํRCSΛٻΊΔཧ࿦͕2000೥͜Ζ ʹఏҊ͞Εͨ[2]ɻ߹੒։ޱϨʔμ(SAR)͸Ϩʔμηϯ αʔͷҠಈʹΑΔ૬ରతʹݻఆͨ͠໨ඪ෺ମͷࢄཚք σʔλΛऔಘ͢Δͷʹର͠ɺISAR͸෺ମͷ(ճస)Ҡಈ ʹΑΔి࣓քΛऔಘ͢Δ໊শͰ͋Γɺ਺ֶతʹ͸શ͘ಉ ͡ཧ࿦ମܥͱͳΔ[3]ɻISAR͋Δ͍͸SARը૾ࣗମΛࢄ ཚ෺ମ͔Βࢄཚ͢Δి࣓քͦͷ΋ͷͱΈΔ͜ͱ͕Ͱ͖ɺ ͜ΕΛجʹ͢ΔͱԕํͰͷRCSύλʔϯ͕ධՁͰ͖Δͱ ߟ͑Δɻ ೾ಈͷ఻ൖ͸೾ݯ͔Βͷ௚઀తͳ݁ՌͰ͋Δͱͯ͠΋ ྑ͍͠ɺ೾ݯͱ؍ଌ఺ͷؒͷ౳Ձతͳ೾ݯ͕ݪҼͱͯ͠ ΋ྑ͍ɻສ෺͸ݪҼ͕͋ͬͯ݁Ռ͕͋ΔΑ͏ʹɺ͋Δྖ Ҭͷి࣓ք͕ԿΒ͔ͷํ๏Ͱ෼͔Ε͹ɺଞͷྖҬͰͷి ࣓ք͸ཧ࿦తʹ༧ଌͰ͖Δɻ͢ͳΘͪNFFFTͱ͸ɺऔಘ ͨ͠ඃଌఆ෺ͷपΓͷి࣓ք͔ΒଞͷྖҬͰͷి࣓քΛ ධՁ͢Δ૯শͰ͋Δɻ্ड़ͷϨʔμը૾͸ର৅෺ͷ౳Ձ తͳ೾ݯ෼෍ͱΈΔ͜ͱ͕Ͱ͖ɺඃܭଌ෺ͷࢄཚ৘ใ͕ ಺แ͞Ε͍ͯΔͱਪఆͰ͖Δɻ݁ہͷͱ͜Ζɺখ͞ͳ೾ ݯͷू߹ͱͯ͠ͷϨʔμը૾͕ཧ࿦ߏஙͰ͖Ε͹ɺ౰֘ ࢄཚମͷԕํRCS͕ධՁՄೳͱͳΔ[4,5]ɻຊݚڀ͸͜ ͷม׵ཧ࿦ͷ਺ֶతͳఆࣜͱ࣮ࡍతͳଌఆ্ͷߟ࡯Λٞ ࿦͢Δ΋ͷͰ͋Δ[6]ɻ ISAR/SARʹ͓͚Δ௨ৗͷԠ༻Ͱ͸ɺϨʔμͱ໨ඪ෺ମ ؒͷڑ཭͕ޓ͍ʹԕํྖҬͰߏ੒͞Ε͓ͯΓɺ࣮༻্Կ Βͷ໰୊΋ͳ͍ɻ͔͠͠ͳ͕Βɺ͜͜Ͱٞ࿦͢ΔϨʔμ ը૾ʹΑΔNFFFT͸ޓ͍ʹۙ๣ྖҬͰܭଌσʔλΛऔಘ ͢Δख๏Ͱ͋Δ[7,8]ɻ͜ͷ݁Ռɺେ͖͘ೋͭͷ৺഑ࣄ ͕༧૝͞ΕΔɻҰͭ͸ۙ๣Ͱ഑ஔ͞ΕΔϓϩʔϒΞϯς φͱඃܭଌ෺ؒͷڑ཭͕େ͖͘มԽ͢Δ໰୊Ͱ͋Γɺ͜ Ε͔ΒಘΒΕΔܭଌσʔλʹ͸େ͖ͳڧ౓͕ࠩੜ͡Δɻ ͜Ε͕Ϩʔμը૾ͷ(য఺)ϘέͱͳͬͯݱΕΔɻԕํ RCS͸ੜ੒ը૾͔Β༠ಋ͢ΔͷͰɺେ͖ͳޡ͕ࠩൃੜ͢ Δ͜ͱ΋ߟ͑ΒΕΔɻͦ͜Ͱɺ͜ͷ໰୊Λࠀ෰͢ΔͨΊ ʹɺஶऀ౳͸ඃܭଌ෺ʹখ͞ͳಋମٿΛԾఆ͠ɺఆࣜԽ Λݫີʹߦͬͨ[9,10]ɻԕํม׵্ɺ͜Ε͸ੵ෼ॲཧͷ ม਺࠲ඪʹԠͨࣗ͡ಈॏΈ෇͚Ͱ͋ΔͷͰɺয఺ڑ཭ͷ ౳Ձతͳิਖ਼ͱΈΔ͜ͱ͕Ͱ͖Δ༗ޮͳํ๏Ͱ͋Δɻ ΋͏Ұͭͷ৺഑ࣄ͸ɺԕํྖҬʹ͸ͳ͍ۙ๣ྖҬͰͷ ಛ༗ͷࣄ৅ͱͳΔଟॏͷ൓ࣹʹΑΔ݁Ռ͕ͲͷΑ͏ʹӨ ڹ͢Δ͔Ͱ͋Δɻྫ͑͹, ೋຕͷฏ൘͕௚֯ʹަࠩͨ͠ ೋ໘ίʔφʔϦϑϨΫλΛزԿޫֶͰ͍͏ޫઢཧ࿦Ͱߟ ͑Δͱ෼͔Γқ͍ɻϨʔμͷૹड৴Ξϯςφ͕͜ͷλʔ ήοτͱԕํڑ཭ͷؔ܎ʹ͋Δͱ͖ɺૹ৴Ξϯςφ͔Β ์ࣹ͞Εͨ೾ಈ(ޫઢ) ͷਐߦํ޲ͱɺೋຕͷ௚ަฏ൘ Ͱೋճ൓ࣹ͠Ϩʔμʹ໭ͬͯ͘Δ೾ಈ͸ޓ͍ʹฏߦͱͳ Δɻͭ·Γɺԕํ৚ཱ͕͍݅֬ͯ͠Δ͜ͱʹଞͳΒͳ͍ɻ NFFFTܭଌͰ͸ɺ͜ͷঢ়گΛ࠶ݱ͢Δ͜ͱ͕ࠔ೉ͱͳΔɻ ۙ๣ྖҬͰ͸ɺೖࣹޫઢͱ൓ࣹޫઢ͸ฏߦʹͳΔ͜ͱ͸ ͳ͘ɺଟॏ൓ࣹΛੜ੒͢Δ෺ମͷNFFFT͸ਖ਼֬ʹRCSΛ ܭଌͰ͖ͳ͍ͷͰ͸ͳ͍͔ͱ͍͏ࠜڌʹͳ͍ͬͯΔɻߤ ۭػΛྫʹͱΔͱɺ͜ͷଟॏ൓ࣹ͸ۭؾऔΓೖΕޱʹΑ Δڞৼ൓ࣹɺ͋Δ͍͸ෳ਺ͷฏ൘ঢ়ͷ෦Ґ͕௚ަ͍ͯ͠ Δ৔߹ʹ૬౰͢ΔͱࢥΘΕΔ[11]ɻ ද1͸ݱࡏߟ͑ΒΕ͍ͯΔRCSͱΞϯςφܭଌʹର ͢Δ֤छม׵๏Λൺֱͨ͠΋ͷͰ͋Δɻ౰ॳͷNFFFT͸ େ͖ͳిؾ௕Λ΋ͭΞϯςφܭଌʹରͯ͠ݚڀ͞Ε͖ͯ ͨܦҢ͕͋Δɻಉද্ཝͷੵ෼ํఔࣜʹΑΔํ๏͸ɺϓ ϩʔϒ૸ࠪܥʹԠͯ͡ݫີͳؔ܎ࣜΛఆࣜԽͨ͠఻౷త ͳํ๏Ͱ͋ΓɺݱࡏͷΞϯςφNFFFTΛ༻͍ͨࢢൢιϑ τ΢ΣΞͷࠜװͱͳ͍ͬͯΔɻΞϯςφܭଌʹಛԽͨ͠ ੵ෼ํఔࣜʹΑΔNFFFTͰ͸ɺRCSܭଌ͸ෆՄೳͰ͋Δɻ ͦ͜ͰɺಉදͷPO-NFFFTɺAF-NFFFTɺ͓ΑͼISAR-NFFFT

ͳͲ͕RCSܭଌ๏ͱͯ͠ఏҊ͞Ε͍ͯΔɻͨͩɺલऀͷ ೋͭ͸ԿΕ΋ฏ໘೾রࣹ͕৚݅Ͱ͋Γɺ࣮༻্ͷ଍͔ͤͱ ͳ͍ͬͯͨɻ͞ΒʹPO-NFFFT͸ɺ෺ཧޫֶ๏(physical

optics: PO)Λม׵ղੳͷجຊཧ࿦ͱ͍ͯ͠ΔͷͰɺϓ

1.·͕͖͑ ిؾ௕ͷେ͖ͳ෺ମͷϨʔμஅ໘ੵ(radar cross-section: RCS) ΛैདྷͷԕํྖҬͰ௚઀ܭଌ͢Δͷ͸ɺ ࠔ೉Λ൐͏৔߹͕ଟ͍ɻরࣹ೾͕ฏ໘೾ͱΈͳ͞ΕΔ΄ Ͳे෼ԕํͰɺRCS͸ఆٛ͞ΕΔ͔ΒͰ͋Δɻ͜ͷڑ཭ ͷ໨҆͸෇࿥Ͱ΋ߟ࡯͍ͯ͠ΔΑ͏ʹɺD Λඃଌఆ෺ ମͷ࠷େੇ๏ɺλΛଌఆप೾਺ͷ೾௕ͱͯ͠2D2_/λͰ ༩͑ΒΕΔ[1]ɻ͜ͷΑ͏ͳঢ়گʹରͯ͠ɺओʹೋͭͷ ରࡦ͕࠾ΒΕ͍ͯΔɻҰͭ͸େ͖ͳύϥϘϥ൓ࣹڸͷ։ ޱྖҬͷҐ૬ͷଗͬͨి࣓ք಺ʹඃଌఆ෺Λ഑ஔ͢Δ ίϯύΫτϨϯδ๏Ͱ͋Γɺطʹ80೥୅ʹ͸RCS͓Α ͼΞϯςφܭଌͳͲʹ࣮༻Խ͞Ε͍ͯΔɻ΋͏Ұͭ͸ۙ ๣ྖҬͰͷి࣓քΛऔಘ͠ɺͦͷσʔλ͔Βԕํి࣓ք ΛٻΊΔۙ๣քԕํม׵๏(near-field to far-field transformation: NFFFT) Ͱ͋Δɻ͜Ε΋ίϯύΫτϨ ϯδ๏ͱಉ࣌ظʹΞϯςφܭଌ๏ͱͯ͠ݚڀ։ൃ͞Ε ͍͕ͯͨɺ2-wayܭଌͱͳΔRCSධՁʹ͸ద༻͕ࠔ೉Ͱ ͋ͬͨɻ͜ͷ໰୊ʹର͠ɺٯ߹੒։ޱϨʔμ(inverse

synthetic aperture radar: ISAR)ॲཧʹΑͬͯಘΒΕ

ͨϨʔμը૾͔ΒԕํRCSΛٻΊΔཧ࿦͕2000೥͜Ζ ʹఏҊ͞Εͨ[2]ɻ߹੒։ޱϨʔμ(SAR)͸Ϩʔμηϯ αʔͷҠಈʹΑΔ૬ରతʹݻఆͨ͠໨ඪ෺ମͷࢄཚք σʔλΛऔಘ͢Δͷʹର͠ɺISAR͸෺ମͷ(ճస)Ҡಈ ʹΑΔి࣓քΛऔಘ͢Δ໊শͰ͋Γɺ਺ֶతʹ͸શ͘ಉ ͡ཧ࿦ମܥͱͳΔ[3]ɻISAR͋Δ͍͸SARը૾ࣗମΛࢄ ཚ෺ମ͔Βࢄཚ͢Δి࣓քͦͷ΋ͷͱΈΔ͜ͱ͕Ͱ͖ɺ ͜ΕΛجʹ͢ΔͱԕํͰͷRCSύλʔϯ͕ධՁͰ͖Δͱ ߟ͑Δɻ ೾ಈͷ఻ൖ͸೾ݯ͔Βͷ௚઀తͳ݁ՌͰ͋Δͱͯ͠΋ ྑ͍͠ɺ೾ݯͱ؍ଌ఺ͷؒͷ౳Ձతͳ೾ݯ͕ݪҼͱͯ͠ ΋ྑ͍ɻສ෺͸ݪҼ͕͋ͬͯ݁Ռ͕͋ΔΑ͏ʹɺ͋Δྖ Ҭͷి࣓ք͕ԿΒ͔ͷํ๏Ͱ෼͔Ε͹ɺଞͷྖҬͰͷి ࣓ք͸ཧ࿦తʹ༧ଌͰ͖Δɻ͢ͳΘͪNFFFTͱ͸ɺऔಘ ͨ͠ඃଌఆ෺ͷपΓͷి࣓ք͔ΒଞͷྖҬͰͷి࣓քΛ ධՁ͢Δ૯শͰ͋Δɻ্ड़ͷϨʔμը૾͸ର৅෺ͷ౳Ձ తͳ೾ݯ෼෍ͱΈΔ͜ͱ͕Ͱ͖ɺඃܭଌ෺ͷࢄཚ৘ใ͕ ಺แ͞Ε͍ͯΔͱਪఆͰ͖Δɻ݁ہͷͱ͜Ζɺখ͞ͳ೾ ݯͷू߹ͱͯ͠ͷϨʔμը૾͕ཧ࿦ߏஙͰ͖Ε͹ɺ౰֘ ࢄཚମͷԕํRCS͕ධՁՄೳͱͳΔ[4,5]ɻຊݚڀ͸͜ ͷม׵ཧ࿦ͷ਺ֶతͳఆࣜͱ࣮ࡍతͳଌఆ্ͷߟ࡯Λٞ ࿦͢Δ΋ͷͰ͋Δ[6]ɻ ISAR/SARʹ͓͚Δ௨ৗͷԠ༻Ͱ͸ɺϨʔμͱ໨ඪ෺ମ ؒͷڑ཭͕ޓ͍ʹԕํྖҬͰߏ੒͞Ε͓ͯΓɺ࣮༻্Կ Βͷ໰୊΋ͳ͍ɻ͔͠͠ͳ͕Βɺ͜͜Ͱٞ࿦͢ΔϨʔμ ը૾ʹΑΔNFFFT͸ޓ͍ʹۙ๣ྖҬͰܭଌσʔλΛऔಘ ͢Δख๏Ͱ͋Δ[7,8]ɻ͜ͷ݁Ռɺେ͖͘ೋͭͷ৺഑ࣄ ͕༧૝͞ΕΔɻҰͭ͸ۙ๣Ͱ഑ஔ͞ΕΔϓϩʔϒΞϯς φͱඃܭଌ෺ؒͷڑ཭͕େ͖͘มԽ͢Δ໰୊Ͱ͋Γɺ͜ Ε͔ΒಘΒΕΔܭଌσʔλʹ͸େ͖ͳڧ౓͕ࠩੜ͡Δɻ ͜Ε͕Ϩʔμը૾ͷ(য఺)ϘέͱͳͬͯݱΕΔɻԕํ RCS͸ੜ੒ը૾͔Β༠ಋ͢ΔͷͰɺେ͖ͳޡ͕ࠩൃੜ͢ Δ͜ͱ΋ߟ͑ΒΕΔɻͦ͜Ͱɺ͜ͷ໰୊Λࠀ෰͢ΔͨΊ ʹɺஶऀ౳͸ඃܭଌ෺ʹখ͞ͳಋମٿΛԾఆ͠ɺఆࣜԽ Λݫີʹߦͬͨ[9,10]ɻԕํม׵্ɺ͜Ε͸ੵ෼ॲཧͷ ม਺࠲ඪʹԠͨࣗ͡ಈॏΈ෇͚Ͱ͋ΔͷͰɺয఺ڑ཭ͷ ౳Ձతͳิਖ਼ͱΈΔ͜ͱ͕Ͱ͖Δ༗ޮͳํ๏Ͱ͋Δɻ ΋͏Ұͭͷ৺഑ࣄ͸ɺԕํྖҬʹ͸ͳ͍ۙ๣ྖҬͰͷ ಛ༗ͷࣄ৅ͱͳΔଟॏͷ൓ࣹʹΑΔ݁Ռ͕ͲͷΑ͏ʹӨ ڹ͢Δ͔Ͱ͋Δɻྫ͑͹, ೋຕͷฏ൘͕௚֯ʹަࠩͨ͠ ೋ໘ίʔφʔϦϑϨΫλΛزԿޫֶͰ͍͏ޫઢཧ࿦Ͱߟ ͑Δͱ෼͔Γқ͍ɻϨʔμͷૹड৴Ξϯςφ͕͜ͷλʔ ήοτͱԕํڑ཭ͷؔ܎ʹ͋Δͱ͖ɺૹ৴Ξϯςφ͔Β ์ࣹ͞Εͨ೾ಈ(ޫઢ) ͷਐߦํ޲ͱɺೋຕͷ௚ަฏ൘ Ͱೋճ൓ࣹ͠Ϩʔμʹ໭ͬͯ͘Δ೾ಈ͸ޓ͍ʹฏߦͱͳ Δɻͭ·Γɺԕํ৚ཱ͕͍݅֬ͯ͠Δ͜ͱʹଞͳΒͳ͍ɻ NFFFTܭଌͰ͸ɺ͜ͷঢ়گΛ࠶ݱ͢Δ͜ͱ͕ࠔ೉ͱͳΔɻ ۙ๣ྖҬͰ͸ɺೖࣹޫઢͱ൓ࣹޫઢ͸ฏߦʹͳΔ͜ͱ͸ ͳ͘ɺଟॏ൓ࣹΛੜ੒͢Δ෺ମͷNFFFT͸ਖ਼֬ʹRCSΛ ܭଌͰ͖ͳ͍ͷͰ͸ͳ͍͔ͱ͍͏ࠜڌʹͳ͍ͬͯΔɻߤ ۭػΛྫʹͱΔͱɺ͜ͷଟॏ൓ࣹ͸ۭؾऔΓೖΕޱʹΑ Δڞৼ൓ࣹɺ͋Δ͍͸ෳ਺ͷฏ൘ঢ়ͷ෦Ґ͕௚ަ͍ͯ͠ Δ৔߹ʹ૬౰͢ΔͱࢥΘΕΔ[11]ɻ ද1͸ݱࡏߟ͑ΒΕ͍ͯΔRCSͱΞϯςφܭଌʹର ͢Δ֤छม׵๏Λൺֱͨ͠΋ͷͰ͋Δɻ౰ॳͷNFFFT͸ େ͖ͳిؾ௕Λ΋ͭΞϯςφܭଌʹରͯ͠ݚڀ͞Ε͖ͯ ͨܦҢ͕͋Δɻಉද্ཝͷੵ෼ํఔࣜʹΑΔํ๏͸ɺϓ ϩʔϒ૸ࠪܥʹԠͯ͡ݫີͳؔ܎ࣜΛఆࣜԽͨ͠఻౷త ͳํ๏Ͱ͋ΓɺݱࡏͷΞϯςφNFFFTΛ༻͍ͨࢢൢιϑ τ΢ΣΞͷࠜװͱͳ͍ͬͯΔɻΞϯςφܭଌʹಛԽͨ͠ ੵ෼ํఔࣜʹΑΔNFFFTͰ͸ɺRCSܭଌ͸ෆՄೳͰ͋Δɻ ͦ͜ͰɺಉදͷPO-NFFFTɺAF-NFFFTɺ͓ΑͼISAR-NFFFT

ͳͲ͕RCSܭଌ๏ͱͯ͠ఏҊ͞Ε͍ͯΔɻͨͩɺલऀͷ ೋͭ͸ԿΕ΋ฏ໘೾রࣹ͕৚݅Ͱ͋Γɺ࣮༻্ͷ଍͔ͤͱ ͳ͍ͬͯͨɻ͞ΒʹPO-NFFFT͸ɺ෺ཧޫֶ๏(physical optics: PO)Λม׵ղੳͷجຊཧ࿦ͱ͍ͯ͠ΔͷͰɺϓ ϩʔϒ͸ฏ໘૸ࠪʹݶఆ͞Εɺ݁Ռతʹฏ໘্ͷ։ޱ෼ ද1 RCS͓ΑͼΞϯςφܭଌʹର͢Δ֤छۙ๣քԕํม׵๏

Tab.1 NFFFT methods for RCS and antenna measurement.

෍ͷϑʔϦΤม׵ͱͳΔಛ௃͕͋Δɻ͜Ε͸ฏ໘೾͕ೖ ࣹ͢ΔݶΓɺRCSܭଌ͸ݪཧతʹΞϯςφܭଌͱ౳Ձͱ ͳΔ͜ͱ͕෼͔ΔɻҰํɺࡾ൪໨ͷAF-NFFFT͸ஶऀ͕ ఏҊ͍ͯ͠Δม׵๏Ͱ͋Γɺ཭ࢄతͳΞϨΠϑΝΫλʔ

(array factor: AF)Λۙ๣քʹରԠ͍ͤͯ͞ΔͷͰɺ૸

ࠪܥ͸੍ݶ͞Εͳ͍ɻ͔͠͠ɺAF͸཭ࢄϑʔϦΤڃ਺ͱ ౳ՁͰ͋ΔͷͰɺ͜Ε΋ฏ໘೾রࣹ͕৚݅ͱͳΔɻ࠷ޙ ͷཝɺISAR-NFFFT͸ຊ࿦Ͱৄड़͍ͯ͠ΔϨʔμը૾ʹج ͮ͘ม׵๏Ͱ͋Δɻٿ૸ࠪͰͷఆࣜ͸·ཱͩ֬͞Ε͍ͯ ͳ͍͕ɺཧ࿦తʹ͸ՄೳͱࢥΘΕΔɻ ஶऀ౳͕ఏҊ͍ͯ͠Δը૾ϕʔεͷNFFFTʹΑΔ࣮ଌ ݁Ռ͸ɺزԿޫֶճંཧ࿦(GTD)Λ࢖ͬͨཧ࿦ܭࢉ஋ͱ ڻ͘΄Ͳྑ͘Ұக͓ͯ͠Γ[12,13]ɺຊNFFFTཧ࿦ͷߴ ͍༗ޮੑͱԠ༻ੑ͕ظ଴Ͱ͖ΔɻҰํɺ্هͷଟॏ൓ࣹ ͸λʔήοτͷػցతߏ੒ʹґଘͨ͠ి࣓քͷݪཧతͳ ݱ৅Ͱ͋ΔͷͰɺ͜ΕΛԿΒ͔ͷཧ࿦͋Δ͍͸ॲཧ͚ͩ Ͱࠀ෰͢Δͷ͸ɺҰےೄͰ͸ͳ͍ͱ༧૝͍ͯ͠Δɻ͜ͷ Α͏ͳഎܠͷ΋ͱɺຊ࿦Ͱ͸ೋ໘ίʔφʔϦϑϨΫλΛ ʹΑΔNFFFTܭଌΛߦ͍ɺͦͷݱ৅͕Ͳͷఔ౓ͷ΋ͷͳ ͷ͔ௐ΂Δ͜ͱʹ͢Δɻࠓޙɺଟॏࢄཚʹؔ͢ΔGTDͷ ཧ࿦ܭࢉΛߦ͏ҙ޲Ͱ͋Γɺࠓճ͸औಘσʔλͷߟ࡯ʹ ཹΊΔ͜ͱͱ͍ͨ͠ɻ ͯ͞प஌ͷΑ͏ʹɺ೾ݯ͔Βͷ೾ಈ͸Ұൠʹڑ཭ͱ֯ ౓ʹґଘ͍ͯ͠Δɻಛʹࡾ࣍ݩۭؒʹ͓͚Δ֯౓ಛੑ͸ ύλʔϯͱ΋ݺ͹Ε͍ͯΔ૬ରతͳؔ਺Ͱ͋Δɻͦͷ” ύλʔϯ”͸೾ݯ͔Βͷڑ཭ʹԠͯ͡มԽ͢Δ͕ɺ͋Δ ྖҬΛڥʹมԽ͠ͳ͍ڑ཭ม਺ʹಠཱͨ͠ܗʹͳΔɻ͜ ͷڥͷ೾ݯʹ͍ۙ಺ଆΛզʑ͸ۙ๣ྖҬ͓ΑͼFresnel ྖҬɺ֎ଆΛԕํྖҬͱݺΜͰ͍Δɻຊ࿦͓Αͼ෇࿥Ͱ ٞ࿦͍ͯ͠ΔΑ͏ʹɺ͜ͷڑ཭͸Ұൠʹ೾ݯͷେ͖͞ͱ प೾਺ͷؔ܎Ͱ༩͑ΒΕΔɻ͜ͷԕํྖҬʹ͓͚Δి࣓ քͷؔ܎͸ɺΞϯςφ෼໺Ͱͷ์ࣹύλʔϯɺϨʔμ෼ ໺Ͱ͸Ϩʔμஅ໘ੵ(RCS)ͱͯ͠ɺઃܭɺ։ൃɺܭଌͷ ࡍͷॏཁͳࢦඪͱͳ͍ͬͯΔɻ ຊ࿦Ͱ͸, ిؾ௕ͷେ͖ͳ෺ମΛҙࣝ͠, ԁपΛؚΉ ԁ౵૸ࠪͰͷϨʔμը૾ʹج͍ͮͨۙ๣քԕํม׵ʹͭ ͍ͯɺཧ࿦ͷఆࣜͱܭଌ݁ՌΛ͍ࣔͯ͠Δɻ͜ͷม׵๏ ͷΦϦδφϧ͸จݙ[2]Ͱ༩͑ΒΕΔ͕ɺϨʔμը૾ͷ ੜ੒ʹ͸ԕํͰͷදࣔࣜΛ༻͍͓ͯΓɺ͔ͭ૸ࠪ໘͸ೋ ࣍ݩԁपʹݶఆ͞Ε͍ͯΔɻ͜Εʹର͠ɺஶऀ౳͸ੵ෼ ม׵ͷఆࣜԽͷࡍɺෳ਺ͷখ͞ͳಋମٿΛԾఆ͠ɺۙ๣ ྖҬͰͷը૾ੜ੒ͷݫີͳఆࣜԽͰয఺Խؔ਺Λ༠ಋ͠ɺ ۙ๣ྖҬͰͷϨʔμը૾ʹΑΔม׵ͱࡾ࣍ݩԁ౵૸ࠪͷ ఆࣜԽʹରԠ͍ͯ͠Δ[4, 5]ɻैདྷͷදࣔࣜͱൺֱ͢Δ ͱɺ͜ͷؔ਺͸ੵ෼ͷࡍͷয఺ॲཧΛิਖ਼͢ΔҼࢠͱߟ ͑ΒΕɺ෺ମ͕ڧ͍ඇରশੑͷ৔߹ʹ༗ޮʹ࡞༻͢Δ΋ ͷͱߟ͑ΒΕΔɻ͜ͷͨΊɺൺֱతখ͞ͳి೾҉ࣨʹେ ͖ͳඃܭଌ෺Λ࣮૷ͯ͠΋҆ఆͨ݁͠Ռ͕ಘΒΕΔͷͰ ͸ͳ͍͔ͱظ଴͍ͯ͠Δɻ ඃܭଌ෺͕ҰൠͷΞϯςφͷ৔߹ɺΞϯςφͷ࣋ͭ൓ ࣹಛੑ(RCS)͕ܭଌ͞ΕɺΞϯςφͷೖྗ୺(͋Δ͍͸ ग़ྗ୺)ͷΠϯϐʔμϯεʹΑͬͯൺֱతେ͖͘มԽ͢ ΔɻRCSܭଌͷૹड৴ͷૹ৴୺ΛΞϯςφͷೖྗ୺ʹೖ Εସ͑ΔͱɺΞϯςφ΋ͭۙ๣քͱը૾σʔλ͕औಘ͞ ΕΔɻ୯७ʹNFFFTॲཧ͢ΔͱɺΞϯςφۙ๣ը૾ʹΑ Δԕํք͕ܭࢉ͞ΕΔͱਪଌͰ͖Δɻ͜Ε͸ɺ͍ΘΏΔ

Ξϯςφͷԕํ์ࣹύλʔϯʹ૬౰͢Δɻ֯ਲ਼ϗʔϯΞ ϯςφͰ֬ೝͨ͠ͱ͜Ζɺม׵ύλʔϯ͸ϗʔϯͷԕํ ܭࢉ஋ͱ΄΅Ұகͨ݁͠Ռͱͳͬͨɻେ͖ͳ෺ମͷRCS ͋Δ͍͸Ξϯςφͷܭଌʹ͸ɺ૬౰ͷઃඋ͕ඞཁͰ͋Δɻ ͜ͷͨΊɺಉҰม׵ॲཧͰRCSͱΞϯςφ͕ܭଌͰ͖Δ ͜ͱ͸ɺେ͖ͳඅ༻ରޮՌͱͳΔɻ ҰํɺຊݚڀͰ͸ɺܭଌͱม׵ॲཧΛҰׅͯ͠ԁ׈ʹਐ ΊΔͨΊɺҰ࿈ͷܭଌͱܭࢉॲཧΛ࣮ߦ͢Διϑτ΢Σ Ξίʔυͷ։ൃ΋߹Θͤͯߦ͍ͬͯΔɻޙड़͢ΔΑ͏ʹɺ ͜ͷίʔυʹ͸ɺٿɺฏ൘౳ͷۙ๣քΛ༩͑Δཧ࿦Ϟσϧ Λ૊ΈࠐΜͰ͓ΓɺNFFFTͷઃఆਫ਼౓౳ͷࣄલධՁɺ࣌ؒ ࣠Ͱͷෆཁ೾আڈΛ໨తͱͨ͠ߴ଎ϑʔϦΤม׵(fast Fourier transform: FFT)ʹΑΔࣄޙॲཧ΋ରԠՄೳͱ ͍ͯ͠Δɻ ࠷ޙʹຊ࿦จͷߏ੒Λه͓ͯ͘͠ɻ͜ͷޙʹଓ͘ୈ2 અͱ3અͰԁप૸ࠪͱԁ౵૸ࠪʹ͓͚Δۙ๣քԕํฦؐ ཧ࿦ͷݫີͳఆࣜΛߦ͏ɻୈ4અͰ͸ɺ͜ͷཧ࿦Λجʹ ։ൃͨ͠૯߹ධՁιϑτ΢ΣΞγεςϜKOSIPͷ֓ཁͱ γϛϡϨʔγϣϯܭࢉྫͱ࣮ଌม׵ྫΛࣔ͠ɺΞϯςφ ύλʔϯܭଌͷՄೳੑͱଌఆ؀ڥʹؔٞ͠࿦͢Δɻୈ5 અͰ͸ɺ؆୯ͳۚଐฏ൘ΛϞσϧʹͯ͠ɺܭࢉཧ࿦ͱ࣮ ଌม׵݁Ռͱͷൺֱݕ౼Λߦ͍ɺ߹ΘͤͯલઅͰهड़͠ ͨKOSIPͷಛ௕౳ʹ͍ͭͯݴٴ͢Δɻୈ6અͰ͸ɺೋ໘ ίʔφʔϦϑϨΫλΛλʔήοτʹͯ͠ɺۙ๣ྖҬͱԕ ํྖҬʹབྷΜͰɺλʔήοτ಺෦Ͱͷଟॏ൓ࣹʹ͍ͭͯ ߟ࡯͢Δɻ͜͜Ͱͷߟ࡯ͷ݁Ռɺߴ଎ϑʔϦΤม׵ʹΑ Δ࣌ؒྖҬͰͷෆཁ೾཈ѹॲཧͱը૾ۭؒʹ͓͚Δෆཁ ೾আڈॲཧ͸౳ՁͰ͋Δ͜ͱΛࣔ͢ɻୈ7અͰ͸ຊݚڀ ͷ݁࿦ɺ෇࿥Ͱ͸೾ಈి࣓քͷԕํྖҬʹؔ͢Δߟ࡯Λ ·ͱΊ͍ͯΔɻ 2.ԁप૸ࠪͷNFFFTཧ࿦ ਤ1 ʹೋ࣍ݩԁप૸ࠪͷ࠲ඪܥΛࣔ͢ɻϚΠΫϩ೾ ৴߸͸൒ܘρ0Ͱ360౓ํҐํ޲ʹճస͢ΔϓϩʔϒΞ ϯςφ͔Βૹड৴͞ΕΔɻԁ౵૸ࠪͰ͸ɺz-࣠ํ޲ʹ΋ Ҡಈ͢ΔɻಉਤͷΩͰࣔ͢಺ଆͷྖҬ͸ը૾ੜ੒ྖҬ Ͱ͋Γɺ൒ܘρ0ͷϓϩʔϒ૸ࠪ໘ΑΓখ͘͞ɺ࠷େੇ ๏Dͷඃܭଌ෺Λғ͍ͬͯΔ_{(D ≤ 2ρ}max≤ 2ρ0)ɻಉ ਤʹࣔ͢ϓϩʔϒΞϯςφͷࢦ޲ੑΛP (β)Ͱ༩͑Δɻ β ͸ΞϯςφϘΞαΠτ͔࣠Βଌͬͨ֯౓Ͱ͋Γɺͦͷ ϘΞαΠτํ޲͸ճస࣠ͷத৺Λ޲͍͍ͯΔɻྫ͑͹ɺ P (β) = 1, cos β Ͱ͸ɺ෉ʑ૸ࠪ໘ʹਨ௚ͳํ޲ͱ઀ઢํ ޲ͷͳిؾతμΠϙʔϧΛද͢ɻ·ͨɺ൒஋෯Λβ0Ͱ༩ ਤ1 ϞϊελςΟοΫԁप૸ࠪNFFFTͷ࠲ඪܥ

Fig.1 Coordinate system of mono-static circular scanning NFFFT. ͑ͨΨ΢εϏʔϜΞϯςφ͸P (β) = exp[_{− ln 2(β/β}0)2] ͱද͞ΕΔ. ઌͣɺߍਖ਼ܭଌ͔Βٞ࿦͢Δɻߍਖ਼༻ͷࢄཚମΛճస ࣠ͷத৺ͷը૾ੜ੒Ҭʹ഑ஔ͢Δɻܗঢ়͸ಋମٿɺ൘ɺ ίʔφʔϦϑϨΫλͳͲͷཧ࿦஋͕෼͔͍ͬͯΔ෺͕ଟ ͘࠾༻͞ΕΔɻ͜͜Ͱ͸ɺൺֱతখ͍͞αΠζͷࢄཚମ ͱ͢Δɻड৴৴߸ΛEs 0(k)ͱ͢Δͱ(k = 2πf/c,f:ܭଌ प೾਺,c:ޫ଎)ɺԕํྖҬͰͷҰൠදࣔͱͯ͠ɺ E0s(k) = Q(k)A0(k)exp(−2jkρ0) 2√πρ2 0 (1) Λߟ͑Δɻ্ࣜͰɺप೾਺ʹґଘ͢ΔҼࢠ Q(k)͸ૹ ৴ΞϯςφͷిքϨϕϧʹൺྫ͢ΔྔͰ͋ΓɺA0(k) ͸ࢄཚମͷޙํࢄཚʹؔ͢ΔྔͰ͋ΔɻA0(k)͸RCS ͱσ =|A0(k)|2 ͷؔ܎ʹ͋Δɻྫ͑͹ɺ൒ܘaͷిؾ తʹখ͞ͳಋମٿ͸A0(k) = 3√πk2a3ɺిؾతʹେ͖ ͳ೚ҙܗঢ়Ͱਨ௚ೖࣹํ޲ͷ౤Өஅ໘ੵ͕S ͷ৔߹ɺ A0(k) =−jkS/√πͱͳΔ[1]ɻߍਖ਼ϓϩηεͰ͸ɺૹ৴ ΞϯςφͷQ(k)͸(1)ࣜͷٯࢉΛͱΓɺ Q(k) = 2√πρ20 Es 0(k) A0(k) exp(2jkρ0) (2) Ͱ༩͑Δ͜ͱ͕Ͱ͖Δɻ ࣍ʹɺඃܭଌ෺Λը૾ੜ੒Ҭͷ಺෦ʹ഑ஔ͠ɺԁप૸ ࠪͷ৔߹ɺे෼ࡉ͔͍εςοϓδϕ0ͰϓϩʔϒΛํҐํ ޲0≤ ϕ0≤ 2πʹ૸ࠪ͢Δɻप೾਺΋ࡉ͔͍εςοϓδf Ͱे෼ͳଳҬfmin ≤ f ≤ fmaxΛ֬อ͠ɺEs(k, ϕ0)Λ औಘ͢Δɻ͜ͷ૸ࠪܦ࿏͸ඃଌఆ෺ͷۙ๣ྖҬͰ͋Δͷ ͰɺEs_{(k, ϕ} 0)͸௚઀(1)ʹ࢖Θͣɺޙड़͢ΔNFFFTॲ ཧͷೖྗσʔλͱ͢Δɻ

Ξϯςφͷԕํ์ࣹύλʔϯʹ૬౰͢Δɻ֯ਲ਼ϗʔϯΞ ϯςφͰ֬ೝͨ͠ͱ͜Ζɺม׵ύλʔϯ͸ϗʔϯͷԕํ ܭࢉ஋ͱ΄΅Ұகͨ݁͠Ռͱͳͬͨɻେ͖ͳ෺ମͷRCS ͋Δ͍͸Ξϯςφͷܭଌʹ͸ɺ૬౰ͷઃඋ͕ඞཁͰ͋Δɻ ͜ͷͨΊɺಉҰม׵ॲཧͰRCSͱΞϯςφ͕ܭଌͰ͖Δ ͜ͱ͸ɺେ͖ͳඅ༻ରޮՌͱͳΔɻ ҰํɺຊݚڀͰ͸ɺܭଌͱม׵ॲཧΛҰׅͯ͠ԁ׈ʹਐ ΊΔͨΊɺҰ࿈ͷܭଌͱܭࢉॲཧΛ࣮ߦ͢Διϑτ΢Σ Ξίʔυͷ։ൃ΋߹Θͤͯߦ͍ͬͯΔɻޙड़͢ΔΑ͏ʹɺ ͜ͷίʔυʹ͸ɺٿɺฏ൘౳ͷۙ๣քΛ༩͑Δཧ࿦Ϟσϧ Λ૊ΈࠐΜͰ͓ΓɺNFFFTͷઃఆਫ਼౓౳ͷࣄલධՁɺ࣌ؒ ࣠Ͱͷෆཁ೾আڈΛ໨తͱͨ͠ߴ଎ϑʔϦΤม׵(fast Fourier transform: FFT)ʹΑΔࣄޙॲཧ΋ରԠՄೳͱ ͍ͯ͠Δɻ ࠷ޙʹຊ࿦จͷߏ੒Λه͓ͯ͘͠ɻ͜ͷޙʹଓ͘ୈ2 અͱ3અͰԁप૸ࠪͱԁ౵૸ࠪʹ͓͚Δۙ๣քԕํฦؐ ཧ࿦ͷݫີͳఆࣜΛߦ͏ɻୈ4અͰ͸ɺ͜ͷཧ࿦Λجʹ ։ൃͨ͠૯߹ධՁιϑτ΢ΣΞγεςϜKOSIPͷ֓ཁͱ γϛϡϨʔγϣϯܭࢉྫͱ࣮ଌม׵ྫΛࣔ͠ɺΞϯςφ ύλʔϯܭଌͷՄೳੑͱଌఆ؀ڥʹؔٞ͠࿦͢Δɻୈ5 અͰ͸ɺ؆୯ͳۚଐฏ൘ΛϞσϧʹͯ͠ɺܭࢉཧ࿦ͱ࣮ ଌม׵݁Ռͱͷൺֱݕ౼Λߦ͍ɺ߹ΘͤͯલઅͰهड़͠ ͨKOSIPͷಛ௕౳ʹ͍ͭͯݴٴ͢Δɻୈ6અͰ͸ɺೋ໘ ίʔφʔϦϑϨΫλΛλʔήοτʹͯ͠ɺۙ๣ྖҬͱԕ ํྖҬʹབྷΜͰɺλʔήοτ಺෦Ͱͷଟॏ൓ࣹʹ͍ͭͯ ߟ࡯͢Δɻ͜͜Ͱͷߟ࡯ͷ݁Ռɺߴ଎ϑʔϦΤม׵ʹΑ Δ࣌ؒྖҬͰͷෆཁ೾཈ѹॲཧͱը૾ۭؒʹ͓͚Δෆཁ ೾আڈॲཧ͸౳ՁͰ͋Δ͜ͱΛࣔ͢ɻୈ7અͰ͸ຊݚڀ ͷ݁࿦ɺ෇࿥Ͱ͸೾ಈి࣓քͷԕํྖҬʹؔ͢Δߟ࡯Λ ·ͱΊ͍ͯΔɻ 2.ԁप૸ࠪͷNFFFTཧ࿦ ਤ1 ʹೋ࣍ݩԁप૸ࠪͷ࠲ඪܥΛࣔ͢ɻϚΠΫϩ೾ ৴߸͸൒ܘρ0 Ͱ360౓ํҐํ޲ʹճస͢ΔϓϩʔϒΞ ϯςφ͔Βૹड৴͞ΕΔɻԁ౵૸ࠪͰ͸ɺz-࣠ํ޲ʹ΋ Ҡಈ͢ΔɻಉਤͷΩͰࣔ͢಺ଆͷྖҬ͸ը૾ੜ੒ྖҬ Ͱ͋Γɺ൒ܘρ0ͷϓϩʔϒ૸ࠪ໘ΑΓখ͘͞ɺ࠷େੇ ๏D ͷඃܭଌ෺Λғ͍ͬͯΔ_{(D ≤ 2ρ}max≤ 2ρ0)ɻಉ ਤʹࣔ͢ϓϩʔϒΞϯςφͷࢦ޲ੑΛP (β)Ͱ༩͑Δɻ β ͸ΞϯςφϘΞαΠτ͔࣠Βଌͬͨ֯౓Ͱ͋Γɺͦͷ ϘΞαΠτํ޲͸ճస࣠ͷத৺Λ޲͍͍ͯΔɻྫ͑͹ɺ P (β) = 1, cos β Ͱ͸ɺ෉ʑ૸ࠪ໘ʹਨ௚ͳํ޲ͱ઀ઢํ ޲ͷͳిؾతμΠϙʔϧΛද͢ɻ·ͨɺ൒஋෯Λβ0Ͱ༩ ਤ1 ϞϊελςΟοΫԁप૸ࠪNFFFTͷ࠲ඪܥ

Fig.1 Coordinate system of mono-static circular scanning NFFFT. ͑ͨΨ΢εϏʔϜΞϯςφ͸P (β) = exp[_{− ln 2(β/β}0)2] ͱද͞ΕΔ. ઌͣɺߍਖ਼ܭଌ͔Βٞ࿦͢Δɻߍਖ਼༻ͷࢄཚମΛճస ࣠ͷத৺ͷը૾ੜ੒Ҭʹ഑ஔ͢Δɻܗঢ়͸ಋମٿɺ൘ɺ ίʔφʔϦϑϨΫλͳͲͷཧ࿦஋͕෼͔͍ͬͯΔ෺͕ଟ ͘࠾༻͞ΕΔɻ͜͜Ͱ͸ɺൺֱతখ͍͞αΠζͷࢄཚମ ͱ͢Δɻड৴৴߸ΛEs 0(k)ͱ͢Δͱ(k = 2πf/c,f:ܭଌ प೾਺,c:ޫ଎)ɺԕํྖҬͰͷҰൠදࣔͱͯ͠ɺ E0s(k) = Q(k)A0(k)exp(−2jkρ0) 2√πρ2 0 (1) Λߟ͑Δɻ্ࣜͰɺप೾਺ʹґଘ͢ΔҼࢠ Q(k)͸ૹ ৴ΞϯςφͷిքϨϕϧʹൺྫ͢ΔྔͰ͋ΓɺA0(k) ͸ࢄཚମͷޙํࢄཚʹؔ͢ΔྔͰ͋ΔɻA0(k)͸ RCS ͱσ =|A0(k)|2 ͷؔ܎ʹ͋Δɻྫ͑͹ɺ൒ܘaͷిؾ తʹখ͞ͳಋମٿ͸A0(k) = 3√πk2a3ɺిؾతʹେ͖ ͳ೚ҙܗঢ়Ͱਨ௚ೖࣹํ޲ͷ౤Өஅ໘ੵ͕S ͷ৔߹ɺ A0(k) =−jkS/√πͱͳΔ[1]ɻߍਖ਼ϓϩηεͰ͸ɺૹ৴ ΞϯςφͷQ(k)͸(1)ࣜͷٯࢉΛͱΓɺ Q(k) = 2√πρ20 Es 0(k) A0(k) exp(2jkρ0) (2) Ͱ༩͑Δ͜ͱ͕Ͱ͖Δɻ ࣍ʹɺඃܭଌ෺Λը૾ੜ੒Ҭͷ಺෦ʹ഑ஔ͠ɺԁप૸ ࠪͷ৔߹ɺे෼ࡉ͔͍εςοϓδϕ0ͰϓϩʔϒΛํҐํ ޲0≤ ϕ0≤ 2πʹ૸ࠪ͢Δɻप೾਺΋ࡉ͔͍εςοϓδf Ͱे෼ͳଳҬfmin ≤ f ≤ fmaxΛ֬อ͠ɺEs(k, ϕ0)Λ औಘ͢Δɻ͜ͷ૸ࠪܦ࿏͸ඃଌఆ෺ͷۙ๣ྖҬͰ͋Δͷ ͰɺEs_{(k, ϕ} 0)͸௚઀(1)ʹ࢖Θͣɺޙड़͢ΔNFFFTॲ ཧͷೖྗσʔλͱ͢Δɻ ԁ प ૸ ࠪ NFFFT ͸ ૸ ࠪ ԁ प ಺ ͷ RCS ࢉ ग़ ධ Ձ Ͱ ͋ Δɻภ೾͸ૹड৴Ξϯςφͷภ೾໘:ਨ௚(V)͓Αͼਫ ฏ(H)ʹґଘ͍ͯ͠ΔͷͰɺ߹Θͤͯ4௨Γͷภ೾૊߹ͤ VV/VH/HV/HH͕ఆٛͰ͖Δɻೋ࣍ݩԁप૸ࠪ͸ɺߴ͞ํ ޲ͷαΠζʹΑΔૹड৴Ξϯςφͷؔ܎͕ԕํքྖҬʹ ͳ͍ͬͯΔ͜ͱ͕લఏͱͳΔɻଞํɺҰํ޲͚ͩʹ૸ࠪ ͢ΔҰ࣍ݩ૸ࠪ͸ඃܭଌମΛแΈࠐΉʹ͸ෆे෼Ͱ͋Δ ͠ɺ൒ۭؒͷύλʔϯ͔͠ධՁͰ͖ͳ͍ڪΕ΋͋Δɻ য఺Խิਖ਼ॲཧʹ஫໨ͨ͠ఆࣜΛߦ͏ɻϨʔμը૾͔ ΒRCSΛಘΔNFFFTͷجຊεςοϓΛࣔ͢: (1)ը૾Ҭ ಺ʹ͓͚Δࢄཚத৺ͷ෼෍ͱͯ͠ඃܭଌ෺Λද͢ը૾ ψ(x, y)Λੜ੒͢Δۙ๣ࢄཚքΛ༠ಋ͢Δɺ(2)ը૾͕ੜ ੒͞ΕͨͳΒɺ͜ͷࢄཚத৺͔Βͷد༩Λੵ෼දࣔ͠ɺ ඃܭଌ෺ͷ֎෦ͷࢄཚքΛಘΔɺ(3)࠷ޙʹୈ(1)ࣜΛ ࢖ͬͯඃܭଌ෺ͷԕํʹ͓͚ΔRCSΛٻΊΔɻ ҎԼɺిؾతʹখ͞ͳࢄཚମΛϞσϧͱͯ͠ఆࣜԽΛ ਐΊΔ͕ɺ͜Ε͸෺ཧతʹࢄཚத৺Λ༩͑Δ΋ͷͰ͋Γɺ Ұൠͷ෺ମ͸͜ͷݩʑͷࢄཚத৺ͷ૯࿨ͱͯ͠දݱͰ͖ ΔͷͰɺຊ࿦ͰఏҊ͢ΔNFFFT΋ಉ༷ʹҰൠͷ෺ମʹద ༻Ͱ͖Δͱߟ͑Δɻ ۩ମతͳয఺Խؔ਺ʹؔ͠ɺ؆୯ͷͨΊೋ࣍ݩ૸ࠪʹ ͯৄ͘͠ௐ΂ΔɻϨʔμը૾ψ(x, y)͸ࢄཚମͷزԿܗ ঢ়ͱࡐྉʹґଘ͢Δ͕ɺϓϩʔϒΞϯςφͷಛੑ౳ͷܭ ଌܥʹ͸ಠཱ͍ͯ͠Δɻͦ͜Ͱɺ(x = x1, y = y1)ʹஔ͔ Εͨిؾతʹখ͞ͳࢄཚମͷը૾Λdeltaؔ਺: ψ(x, y) = Cδ(x−x1)δ(y−y1) (3) ͰදݱͰ͖Δͱߟ͑ΔɻC ͸ࢄཚମ͕ࢄཚ͢Δࡍͷਖ਼ نԽ܎਺Ͱ͋Δɻిؾతʹখ͞ͳશͯͷ෺ମͷࢄཚ܎਺ ͸प೾਺ͷೋ৐ʹൺྫ͢Δͱ͍͏جຊࣄ࣮͔Βɺؔ܎ࣜ A(k) = ˜Ak2_{͕ಘΒΕΔɻ͜͜ͰɺA˜͸ओʹࡐྉߏ੒ʹ} ΑܾͬͯΊΒΕɺ೾਺ kʹ͸ಠཱ͍ͯ͠Δɻճసରশ ͷ৔߹͸ ϕ0ʹ΋ಠཱ͍ͯ͠Δ(ྫ:൒ܘaͷಋମٿ͸ ˜ A = 3√πa3_{)ɻࠓɺਖ਼نԽ܎਺ΛC = ˜AͰ༩͑Α͏ɻ͜}

ͷͱ͖ɺ࠲ඪiρ0ρ0= ixρ0cos ϕ0+iyρ0sin ϕ0ʹҐஔͨ͠

A(k) = ˜Ak2_{ͷ܎਺Λ΋ͭిؾ௕ͷখ͞ͳجຊࢄཚମʹର} ͠ɺԁप্ͷ఺iρ0ρ0= ixρ0cos ϕ0+iyρ0sin ϕ0Ͱ؍ଌ͠ ͨͱ͖ͷड৴೾ΛٻΊΔͱɺ Es_{(k, ϕ} 0, ρ0) (4) = Q(k)P2(β)k 2_A(k)˜ √ 4π exp(_−2jk|iρρ_{− i}ρρ_0|) � �iρρ_{− i}ρ0ρ0 � �2 ͱͳΔɻه߸i͸୯ҐϕΫτϧΛද͍ͯ͠Δɻ͜ΕΑΓɺ શͯͷํҐํ޲ͱप೾਺ʹΘͨΔۙ๣ίώʔϨϯτքͷ ૯࿨͸ɺ ψ(x, y) = ∫ ∞ 0 ∫ 2π 0 Es(k, ϕ0, ϕ)F (iρρ, iρ0ρ0, k)dkdϕ0 (5) Ͱ༩͑ΒΕΔɻ্ࣜͷॏΈؔ਺F ͸࣍ࣜͷয఺Խؔ਺Ͱ ͋Δ: F (iρρ, iρρ₀, k) (6) = g(iρρ, iρρ₀, k) � �iρρ_{− i}ρρ₀��2 Q(k)P2_(β) exp(2jk|iρρ− iρ0ρ0|). ্ͷؔ਺ʹΑͬͯɺ૸ࠪ໘্ͷ༷ʑͳ࠲ඪͰड৴͢Δ ࢄཚքͷؒͷҐ૬ͱৼ෯͕దਖ਼ʹิਖ਼͞ΕΔɻޙड़͢Δ Α͏ʹɺࣜ(3)Ͱఆٛͨ͠deltaؔ਺Λ༻͍Δͱɺ۩ମ తͳg(iρρ, iρ0ρ0, k)ͷද͕ࣔٻΊΒΕɺ݁ہͷͱ͜Ζɺ ؔ਺F͸ۙ๣ྖҬʹ͓͚Δয఺ิਖ਼Ҽࢠͱͯ͠ৼΔ෣͏ ͜ͱ͕෼͔Δɻ ࠲ඪiρ1ρ1= ixx1+iyy1ʹஔ͔Εͨిؾతʹখ͞ͳࢄཚ ମʹର͠ɺ(4)ࣜ͸ Es 1(k, ϕ0, ρ0) (7) = Q(k)P2(β1) k2_A(k)˜ √ 4π exp(_−2jk|iρ1ρ1− iρ0ρ0|) � �iρ1ρ1− iρ0ρ0 � �2 ͱͳΔɻ͜ͷͱ͖ͷը૾ؔ਺͸࣍ࣜͷΑ͏ʹ༩͑ΒΕΔ: ψ(x, y) = _√A˜ 4π ∫ ∞ 0 ∫ 2π 0 g(iρρ, iρ0ρ0, k) (8) ·P 2_(β 1) P2_(β) |iρρ− iρ0ρ0| 2 |iρ1ρ1− iρ0ρ0| 2e 2jks_k2_dkdϕ 0.

͜͜Ͱɺs =|iρρ−iρ0ρ0|−|iρ1ρ1−iρ0ρ0|Ͱ͋Δɻࢄཚମ

ͷۙ๣Ͱ͸ɺiρρ→ iρ1ρ1Ͱ͋ΔͷͰɺβ→ β1ͱͳͬͯɺ s_{≈ (x}1− x) cos α + (y1− y) sin α (9) ͕ಘΒΕΔɻ֯α͸ϕΫτϧiρ0ρ0− iρρͱixͷ੒֯͢ ౓Λࢦ͢(ਤ1ࢀর)ɻ͜Ε͸α = α(iρρ, iρρ0)ͷؔ਺Ͱ ͋Δɻ૸ࠪ໘͸ը૾ੜ੒໘ΛแΉͷͰ(ρ0> ρmax), ϕ0 ͕0͔Β2πͰมԽ͢Δͱ͖ɺα͸2π૿Ճ͢ΔɻҎ্Α Γɺը૾ؔ਺͸ ψ(x, y)_≈√A˜ 4π ∫ ∞ 0 ∫ 2π 0 g(iρρ, iρ0ρ0, k) (10)

· exp{2jk[(x1− x) cos α + (y1− y) sin α]k2}dkdϕ0

ͱۙࣅͰ͖Δɻ

೾਺kͱϕ0Λkx= 2k cos αͱky= 2k sin αʹม਺ม

׵͢Δͱɺ೾਺ྖҬͷؔ܎ࣜ

dkxdky = 4kα′(iρρ, iρ0ρ0)dkdϕ0, (11)

͕ಘΒΕΔͷͰɺը૾ؔ਺(10)͸࣍ͷΑ͏ʹදࣔͰ͖Δ: ψ(x, y)_≈ A˜ 8√π ∫ ∞ −∞ ∫ ∞ −∞ g(iρρ, iρ0ρ0, k) α′_{(iρρ, iρ} 0ρ0) (12)

· exp{jkx(x1− x) + jky(y1− y)}kdkxdky.

͜͜Ͱɺؔ਺gΛ g(iρρ, iρ0ρ0, k) = 2α′(iρρ, iρ0ρ0) kπ3/2 (13) Ͱ༩͑Δɻ͜ͷଥ౰ੑ͸࣍ͷΑ͏ʹ͔ͯ֬͠ΊΒΕΔɻ deltaؔ਺ͷఆٛࣜ (2π)2δ(x_{− x}1)δ(y− y1) (14) = ∫ ∞ −∞ ∫ ∞ −∞

exp{jkx(x1−x) + jky(y1−y)}dkxdky

Λ࢖͍[14]ɺC = ˜Aͱͯ͠, iρρ_{→ i}ρ1ρ1ͷͱ͖ͷ(12) ࣜΛܭࢉ͢Δͱɺ(3)ࣜͷψ(x, y) = Cδ(x_−x1)δ(y−y1) ʹؼண͢Δɻ ֯౓α͸ϕ0ʹΑΓ۩ମతͳද͕ࣔࣜ༠ಋͰ͖Δɻϕ0 ʹؔ͢Δඍ෼ԋࢉΛߦ͏ͱɺ α′(iρρ, iρ0ρ0) = ρ2 0χ(iρρ, iρ0ρ0) |iρρ− iρ0ρ0| , (15) χ(iρρ, iρ0ρ0) = 1− ρ ρ0cos(ϕ− ϕ0) ͕ٻΊΒΕΔɻ͜ΕΑΓɺิਖ਼Ҽࢠͱͯ͠௚ͪʹ͕࣍ࣜ ٻΊΒΕΔ: g(iρρ, iρρ0, k) = 2ρ2 0χ(iρρ, iρ0ρ0) π3/2_{k|iρρ− i} ρ0ρ0| . (16) ैͬͯɺয఺Խؔ਺͸ F (iρρ, iρρ0, k) = 2ρ 2 0χ(iρρ, iρ0ρ0) π3/2_kQ(k)P2_(β)e 2jk|iρρ−iρ0ρ0| (17) ͱද͞ΕΔɻҰํɺࢦ޲ੑΞϯςφͷ֯౓β͸͔࣍ࣜΒ ܭࢉͰ͖Δ:

cos β = χ(iρρ, iρ0ρ0)

2_|iρρ_{− i}ρ0ρ0| . (18) ࣜ(17)ʹରԠ͢Δैདྷͷয఺Խؔ਺͸χ(iρρ, iρ0ρ0) = 1Ͱ͋Δ[2,8]ɻ͜Ε͸ࣜ(15)Λݟͯ΋෼͔ΔΑ͏ʹɺ ρ0→ ∞ (ϓϩʔϒ͕ԕํʹଘࡏ)͔ɺρ→ 0 (ࢄཚମ͕ ࠲ඪͷݪ఺ʹଘࡏ)ͷͲͪΒ͔Λҙຯ͍ͯ͠Δɻ͜ͷ͜ ͱ͸ɺࣜ(16)ΛऔΓೖΕΔ͜ͱͰɺΑΓখ͞ͳి೾҉ࣨ Ͱͷܭଌɺͭ·Γ͸ࢄཚத৺͕ݪ఺͔Βภ৺͍ͯ͠Δܭ ଌͰͷ໰୊͕ղܾͰ͖Δͱ͍͏͜ͱΛ͍ࣔࠦͯ͠Δɻ Ҏ্ΑΓɺRCSͷ۩ମతͳද͕ࣔՄೳͱͳͬͨɻશͯ ͷϨʔμը૾͸఺ঢ়ࢄཚத৺ͷ෼෍Ͱ͋ΓɺͦΕނɺࢄ ཚք͸͜ΕΒࢄཚத৺͔Βͷٿ໘೾ͷॏͶ߹Θͤͱͯ͠ ද͢͜ͱ͕Ͱ͖Δɻ͜ΕΛ਺ࣜͰදݱ͢Δͱɺ Es(k, ϕ0, ρ0) (19) = k 2_Q(k) √ 2π ∫∫ Ω ψ(x, y)P2(β)e 2jk|iρρ−iρ0ρ0)| |iρρ_{− i}ρ0ρ0)| dxdy ͱͳΔɻલड़(3)ࣜͷ(x, y)͸ࣜ(7)ʹ΋ద༻Ͱ͖Δɻ ͦ͜Ͱɺࣜ(5)ͱ(19)ͷੵ෼ม׵ରʹண໨͢Δͱɺදࣔ ࣜ(19)͸೚ҙͷρ0ʹର͠੒ཱ͢ΔͷͰɺϨʔμஅ໘ੵ ͷఆٛࣜ: σ = 4π��rEs_(r)/Ei 0 � �2 ΑΓɺೋ࣍ݩͰͷఆٛࣜ σ(k, ϕ0) = lim ρ0→∞ 4πρ20 � � � �E s_{(k, ϕ} 0, ρ0) Ei 0 � � � � 2 (20) ͕ಘΒΕΔɻ͞Βʹɺࣜ(19)ͷEs_{(k, ϕ} 0, ρ0)Ͱρ0→ ∞ ͱ͠ɺೖࣹքʹରͯؔ͠܎ࣜEi 0= Q(k)e−jkρ0/ρ0 Λ࢖ ͏ͱɺP (β)_{→ 1, |i}ρρ_−iρ0ρ0| ≈ ρ0−ρ cos(ϕ−ϕ0)ͱͰ ͖ΔͷͰɺ࠷ऴతʹ࣍ͷද͕ࣔࣜಋ͔ΕΔ: σ(k,ϕ0) = k4 � � � � ∫∫ Ω

ψ(x, y)e2jk(x cos ϕ0+y sin ϕ0)_dxdy

� � � � 2 . (21) ͜Ε͕ԁप૸ࠪʹ͓͚ΔϨʔμը૾͔ΒԕํͰͷRCSΛ ༩͑Δ࠷ऴతͳެࣜͰ͋Δɻ ؍ଌ఺ρ0Λ༗ݶͷ··NFFFTॲཧΛߦ͏ͱɺͦͷڑ ཭ͰͷRCS͕ධՁͰ͖Δɻۙڑ཭RCS͸ͦͷڑ཭Ͱେ͖ ͘มಈ͢Δ৔߹͕͋Δɻࣗಈंিಥ๷ࢭϨʔμͳͲ͸ɺ Ϩʔμର৅෺ମͱͷڑ཭͕༗ݶͷ৔߹ʹ૬౰͢Δɻ͜ͷ Α͏ͳϨʔμͷਫ਼ີͳઃܭʹ͸ɺର৅෺ͷۙڑ཭RCSͷ ධՁ͕༗༻ͳ৘ใͱͳΔɻ ্ͯ͞ड़ͷΑ͏ʹɺ૸ࠪ൒ܘ͕λʔήοτͷαΠζͱ ಉ͡ఔ౓Ͱ͋Ε͹ɺิਖ਼ؔ਺gʹΑΔվળޮՌ͕༧૝͞ ΕΔɻͭ·Γɺ͍ΘΏΔλʔήοτͷࢄཚத৺͕زԿத ৺͔Βେ͖ͣ͘ΕΔ৔߹ʹେ͖ͳޮՌ͕ظ଴Ͱ͖Δɻ͜ ͷ਺஋ྫΛਤ2ʹࣔ͢ɻρ_{→0 or ρ}0→∞ͷͱ͖ɺρ≈ρ0 ͓Α͓ͼg2D(⃗ρ, ⃗ρ0)→1ͱ઴ۙ͢Δ͜ͱ͕෼͔Δɻ ਤ3͸ຊઅͰࣔͨ͠ཧ࿦ࣜΛ൒ܘͷҟͳΔೋͭͷখ͞ ͳಋମٿͰܭࢉͨ݁͠ՌͰ͋Δɻ͜͜ͰɺϓϩʔϒΞϯ ςφͷ૸ࠪ൒ܘ͸ρ0= 1.5 mɺத৺प೾਺͸f = 1 GHzɺ૟ Ҿεςοϓ͸0.1ͱ0.5 GHzͰ͋Δɻิਖ਼ؔ਺ʹΑΔେ ͖ͳޮՌ͕֬ೝͰ͖Δɻ·ͨ༧૝͞ΕΔΑ͏ʹɺप೾਺ εςοϓͷখ͍͞ํ͕෼ղೳ͸ߴ͍͜ͱ͕෼͔Δɻ 3.ԁ౵૸ࠪNFFFT΁ͷ֦ுཧ࿦ લઅͷೋ࣍ݩԁप૸ࠪʹҾ͖ଓ͖ɺຊઅͰ͸ࡾ࣍ݩԁ ౵૸ࠪͷNFFFTʹ͍ͭͯٞ࿦͢Δɻԁ౵૸ࠪ͸ԁप૸ࠪ

͕ಘΒΕΔͷͰɺը૾ؔ਺(10)͸࣍ͷΑ͏ʹදࣔͰ͖Δ: ψ(x, y)_≈ A˜ 8√π ∫ ∞ −∞ ∫ ∞ −∞ g(iρρ, iρ0ρ0, k) α′_{(iρρ, iρ} 0ρ0) (12)

· exp{jkx(x1− x) + jky(y1− y)}kdkxdky.

͜͜Ͱɺؔ਺gΛ g(iρρ, iρ0ρ0, k) = 2α′(iρρ, iρ0ρ0) kπ3/2 (13) Ͱ༩͑Δɻ͜ͷଥ౰ੑ͸࣍ͷΑ͏ʹ͔ͯ֬͠ΊΒΕΔɻ deltaؔ਺ͷఆٛࣜ (2π)2δ(x_{− x}1)δ(y− y1) (14) = ∫ ∞ −∞ ∫ ∞ −∞

exp{jkx(x1−x) + jky(y1−y)}dkxdky

Λ࢖͍[14]ɺC = ˜Aͱͯ͠, iρρ_{→ i}ρ1ρ1ͷͱ͖ͷ(12) ࣜΛܭࢉ͢Δͱɺ(3)ࣜͷψ(x, y) = Cδ(x_−x1)δ(y−y1) ʹؼண͢Δɻ ֯౓α͸ϕ0ʹΑΓ۩ମతͳද͕ࣔࣜ༠ಋͰ͖Δɻϕ0 ʹؔ͢Δඍ෼ԋࢉΛߦ͏ͱɺ α′(iρρ, iρ0ρ0) = ρ2 0χ(iρρ, iρ0ρ0) |iρρ− iρ0ρ0| , (15) χ(iρρ, iρ0ρ0) = 1− ρ ρ0cos(ϕ− ϕ0) ͕ٻΊΒΕΔɻ͜ΕΑΓɺิਖ਼Ҽࢠͱͯ͠௚ͪʹ͕࣍ࣜ ٻΊΒΕΔ: g(iρρ, iρρ0, k) = 2ρ2 0χ(iρρ, iρ0ρ0) π3/2_{k|iρρ− i} ρ0ρ0| . (16) ैͬͯɺয఺Խؔ਺͸ F (iρρ, iρρ0, k) = 2ρ 2 0χ(iρρ, iρ0ρ0) π3/2_kQ(k)P2_(β)e 2jk|iρρ−iρ0ρ0| (17) ͱද͞ΕΔɻҰํɺࢦ޲ੑΞϯςφͷ֯౓β͸͔࣍ࣜΒ ܭࢉͰ͖Δ:

cos β = χ(iρρ, iρ0ρ0)

2_|iρρ_{− i}ρ0ρ0| . (18) ࣜ(17)ʹରԠ͢Δैདྷͷয఺Խؔ਺͸χ(iρρ, iρ0ρ0) = 1Ͱ͋Δ[2,8]ɻ͜Ε͸ࣜ(15)Λݟͯ΋෼͔ΔΑ͏ʹɺ ρ0→ ∞ (ϓϩʔϒ͕ԕํʹଘࡏ)͔ɺρ→ 0 (ࢄཚମ͕ ࠲ඪͷݪ఺ʹଘࡏ)ͷͲͪΒ͔Λҙຯ͍ͯ͠Δɻ͜ͷ͜ ͱ͸ɺࣜ(16)ΛऔΓೖΕΔ͜ͱͰɺΑΓখ͞ͳి೾҉ࣨ Ͱͷܭଌɺͭ·Γ͸ࢄཚத৺͕ݪ఺͔Βภ৺͍ͯ͠Δܭ ଌͰͷ໰୊͕ղܾͰ͖Δͱ͍͏͜ͱΛ͍ࣔࠦͯ͠Δɻ Ҏ্ΑΓɺRCSͷ۩ମతͳද͕ࣔՄೳͱͳͬͨɻશͯ ͷϨʔμը૾͸఺ঢ়ࢄཚத৺ͷ෼෍Ͱ͋ΓɺͦΕނɺࢄ ཚք͸͜ΕΒࢄཚத৺͔Βͷٿ໘೾ͷॏͶ߹Θͤͱͯ͠ ද͢͜ͱ͕Ͱ͖Δɻ͜ΕΛ਺ࣜͰදݱ͢Δͱɺ Es(k, ϕ0, ρ0) (19) = k 2_Q(k) √ 2π ∫∫ Ω ψ(x, y)P2(β)e 2jk|iρρ−iρ0ρ0)| |iρρ_{− i}ρ0ρ0)| dxdy ͱͳΔɻલड़(3)ࣜͷ(x, y)͸ࣜ(7)ʹ΋ద༻Ͱ͖Δɻ ͦ͜Ͱɺࣜ(5)ͱ(19)ͷੵ෼ม׵ରʹண໨͢Δͱɺදࣔ ࣜ(19)͸೚ҙͷρ0ʹର͠੒ཱ͢ΔͷͰɺϨʔμஅ໘ੵ ͷఆٛࣜ: σ = 4π��rEs_(r)/Ei 0 � �2 ΑΓɺೋ࣍ݩͰͷఆٛࣜ σ(k, ϕ0) = lim ρ0→∞ 4πρ20 � � � �E s_{(k, ϕ} 0, ρ0) Ei 0 � � � � 2 (20) ͕ಘΒΕΔɻ͞Βʹɺࣜ(19)ͷEs_{(k, ϕ} 0, ρ0)Ͱρ0→ ∞ ͱ͠ɺೖࣹքʹରͯؔ͠܎ࣜEi 0= Q(k)e−jkρ0/ρ0 Λ࢖ ͏ͱɺP (β)_{→ 1, |i}ρρ_−iρ0ρ0| ≈ ρ0−ρ cos(ϕ−ϕ0)ͱͰ ͖ΔͷͰɺ࠷ऴతʹ࣍ͷද͕ࣔࣜಋ͔ΕΔ: σ(k,ϕ0) = k4 � � � � ∫∫ Ω

ψ(x, y)e2jk(x cos ϕ0+y sin ϕ0)_dxdy

� � � � 2 . (21) ͜Ε͕ԁप૸ࠪʹ͓͚ΔϨʔμը૾͔ΒԕํͰͷRCSΛ ༩͑Δ࠷ऴతͳެࣜͰ͋Δɻ ؍ଌ఺ρ0 Λ༗ݶͷ··NFFFTॲཧΛߦ͏ͱɺͦͷڑ ཭ͰͷRCS͕ධՁͰ͖Δɻۙڑ཭RCS͸ͦͷڑ཭Ͱେ͖ ͘มಈ͢Δ৔߹͕͋Δɻࣗಈंিಥ๷ࢭϨʔμͳͲ͸ɺ Ϩʔμର৅෺ମͱͷڑ཭͕༗ݶͷ৔߹ʹ૬౰͢Δɻ͜ͷ Α͏ͳϨʔμͷਫ਼ີͳઃܭʹ͸ɺର৅෺ͷۙڑ཭RCSͷ ධՁ͕༗༻ͳ৘ใͱͳΔɻ ্ͯ͞ड़ͷΑ͏ʹɺ૸ࠪ൒ܘ͕λʔήοτͷαΠζͱ ಉ͡ఔ౓Ͱ͋Ε͹ɺิਖ਼ؔ਺gʹΑΔվળޮՌ͕༧૝͞ ΕΔɻͭ·Γɺ͍ΘΏΔλʔήοτͷࢄཚத৺͕زԿத ৺͔Βେ͖ͣ͘ΕΔ৔߹ʹେ͖ͳޮՌ͕ظ଴Ͱ͖Δɻ͜ ͷ਺஋ྫΛਤ2ʹࣔ͢ɻρ_{→0 or ρ}0→∞ͷͱ͖ɺρ≈ρ0 ͓Α͓ͼg2D(⃗ρ, ⃗ρ0)→1ͱ઴ۙ͢Δ͜ͱ͕෼͔Δɻ ਤ3͸ຊઅͰࣔͨ͠ཧ࿦ࣜΛ൒ܘͷҟͳΔೋͭͷখ͞ ͳಋମٿͰܭࢉͨ݁͠ՌͰ͋Δɻ͜͜ͰɺϓϩʔϒΞϯ ςφͷ૸ࠪ൒ܘ͸ρ0= 1.5 mɺத৺प೾਺͸f = 1 GHzɺ૟ Ҿεςοϓ͸0.1ͱ0.5 GHzͰ͋Δɻิਖ਼ؔ਺ʹΑΔେ ͖ͳޮՌ͕֬ೝͰ͖Δɻ·ͨ༧૝͞ΕΔΑ͏ʹɺप೾਺ εςοϓͷখ͍͞ํ͕෼ղೳ͸ߴ͍͜ͱ͕෼͔Δɻ 3.ԁ౵૸ࠪNFFFT΁ͷ֦ுཧ࿦ લઅͷೋ࣍ݩԁप૸ࠪʹҾ͖ଓ͖ɺຊઅͰ͸ࡾ࣍ݩԁ ౵૸ࠪͷNFFFTʹ͍ͭͯٞ࿦͢Δɻԁ౵૸ࠪ͸ԁप૸ࠪ ਤ2 ԁप૸ࠪʹ͓͚Δิਖ਼ؔ਺gͷৼΔ෣͍

Fig.2 Focus correcting function g for circular scan.

(a) 2-D circular scanning NFFFT configuration

(b) Radar image obtained from (a) parameters

(c) RCS by the radar image obtained from (b)

ਤ3 ԁप૸ࠪNFFFTʹΑΔೋͭͷಋମٿʹΑΔRCS

Fig.3 Theoretical 2-sphere RCS in circular NFFFT.

ਤ4 ԁ౵૸ࠪNFFFTͷ࠲ඪܥ:૸ࠪ໘ͱը૾ੜ੒ྖҬ

Fig.4 Coordinate system of cylindrical scanning NFFFT: scanning surface and imaging area.

໘ʹਨ௚ͳඃܭଌ෺ͷߴ͞ํ޲ͷిؾ௕͕େ͖͍৔߹ʹ ༗ޮͰ͋Δɻਤ4ʹԁ౵૸ࠪͷ࠲ඪܥΛࣔ͢ɻجຊతʹ ԁप૸ࠪͱಉ͡ม਺Λ࠾༻͓ͯ͠Γɺԁप࠲ඪʹz-࣠Λ Ճ͑ͨ΋ͷͱͳΔɻ͜͜Ͱड़΂Δԁ౵૸ࠪNFFFTͰ͸ɺ ૸ࠪ໘ʹਨ௚ͳਫฏ໘಺ϞϊελςΟοΫRCS: σ(k, ϕ) ΛٻΊΔۙ๣քσʔλΛ૝ఆ͢Δɻ ࠓɺRCSͱը૾ؔ਺ͷجຊࣜ(21)ͷࣗવͳԆ௕ͱͯ͠ɺ σ(k, ϕ) (22) = k4 � � � � ∫∫∫ V

Ψ(x, y, z)e2jk(x cos ϕ+y sin ϕ)dxdydz

� � � � 2 Λߟ͑Δɻ͜͜ͰɺΨ(x, y, z = r)͸ඃܭଌ෺ͷࡾ࣍ݩ Ϩʔμը૾Ͱ͋Γɺۙ๣ࢄཚքEs near(k, ϕ0, z0)ΑΓɺ Ψ(r) (23) = ∫ ∞ 0 dk ∫ 2π 0 dϕ0 ∫ ∞ −∞ dz0Enears (k, ϕ0, z0)F (r, r0.k)

ͱٻΊΒΕΔɻr0= ixρ0cos ϕ0+iyρ0sin ϕ0+izz0͸૸ࠪ

ͷ࠲ඪɺͦͯ͠ F (r, r0, k) = Acalχ(x, y, ϕ0) π3_Es cal(k)|r − r0| e2jk(|r−r0|)−ρ0₍₂₄₎ ͸ࡾ࣍ݩԁ౵࠲ඪܥͷয఺Խؔ਺Ͱ͋Γɺԁप૸ࠪͷ৔ ߹ͱಉ͡Α͏ʹɺ૸ࠪ໘্ͷҟͳͬͨ఺Ͱͷࢄཚքͱͷ Ґ૬ɺৼ෯ͷࠩΛิਖ਼͢Δ͜ͱ͕Ͱ͖Δɻ·্ͨࣜʹ͸ɺ ߍਖ਼࣌ͷࢄཚମ͔ΒͷσʔλEs cal(k)ʹର͢Δԕํք܎ ਺Acal(k)Λߟྀͨ͠දࣔͱ͍ͯ͠Δɻؔ਺ χ(x, y, ϕ0) = 1− x ρ0 cos ϕ0− y ρ0 sin ϕ0 (25) ͸ԁप૸ࠪͰಋೖͨ͠ิਖ਼ؔ਺Ͱ͋ΔɻҎԼɺੵ෼දࣔ ࣜ(22)ͱ(23)ʹ͍ͭͯௐ΂Δɻ ઌͣɺߍਖ਼༻ࢄཚମʹΑΔࢄཚքΛ Ecals (k) = E0(k) Acal(k) √ 4πρ2 0 e−2jkρ0 ₍₂₆₎ Ͱද͠ɺয఺Խؔ਺Λૹ৴Ξϯςφͷ։ޱ͔Βͷ์ࣹք E0(k)Ͱ༩͑Δɻ ࣍ʹɺϓϩʔϒΞϯςφͷࢦ޲ੑύλʔϯP (β)ʹͭ ͍ͯߟ͑Δɻ͜͜Ͱ͸, ૹड৴Ξϯςφ͕ಉ͡΋ͷͱ͢ Δɻ֯β ͸ΞϯςφϘΞαΠτ࣠ilͱɺ఺r0͔Βݟͨ ը૾্ͷ఺r΁ͷํ޲ͱͷؒͰ࡞ΒΕΔ֯౓Ͱ͋Δɻ͜ ͷͱ͖ɺil=−iρ0ρ0, iρ0ρ0= ixcos ϕ0+iysin ϕ0ͷؔ܎

͕ܭࢉͰ͖ɺ͜ͷ݁Ռɺয఺Խؔ਺͸࣍ࣜͷΑ͏ʹͳΔ: F (r, r0, k) = 2ρ 2 0χ(x, y, ϕ0)e2jk|r−r0| π5/2_E 0(k)P2(β)|r − r0| . (27) ্ࣜ͸఺r1 ʹ͋Δిؾతʹখ͞ͳࢄཚମΛԾఆͯ͠ɺ (24)͔ࣜΒ༠ಋ͍ͯ͠Δɻͭ·Γɺԕํք܎਺ΛA(k) ͱ͢Δͱɺdeltaؔ਺Ͱ༩͑ͨϨʔμը૾ Φ1(r) = δ(r− r1)A1(k)/k2͸Ξϯςφύλʔϯؔ਺P (β)ʹಠཱͯ͠ ͍ΔͷͰɺमਖ਼ͨ͠RCS஋σ1=|A1(k)|2͕ٻΊΒΕΔɻ ࠷ޙ͸(22)ࣜʹؔ͢Δ΋ͷͰɺ͜ΕΛॻ͖׵͑Δͱɺ σ(k, ϕ) = k4 � � � � ∫∫ Ω

Φ(x, y)e2jk(x cos ϕ+y sin ϕ)dxdy

� � � � 2 (28) ͱͳΔɻ͜͜ͰɺΩ͸ԁ౵૸ࠪͷਫฏஅ໘ʹ͋Δը૾ੜ ੒Ҭ(ਤ1)Ͱ͋ΓɺҰํɺΦ(x, y)͸ Φ(x, y) = ∫ ∞ −∞ Ψ(r)dz (29) Ͱఆٛ͞ΕΔɻ(27)ͱ(23)ࣜΛ(29)ࣜʹ୅ೖ͢Δͱɺ Φ(r) (30) = ∫ ∞ 0 dk ∫ 2π 0 dϕ0 ∫ ∞ −∞ dz0Enears (k, ϕ0, z0) χ(x, y, ϕ0) E0(k) T ͕ಘΒΕΔɻ͜͜Ͱɺඃੵ෼ؔ਺ͷT͸ T = 2ρ 2 0 π5/2 ∫ ∞ −∞ e2jk|r−r0| P2_{(β)|r − r} 0| dz (31) Ͱ༩͑ΒΕΔɻ ࠓɺϓϩʔϒΞϯςφ͸ແࢦ޲ੑͰ͋Δͱ͢Δͱɺ P (β) = 1Ͱ͋ΔͷͰɺ্ࣜ͸ T = 2jρ 2 0 π3/2H (1) 0 (2k|iρρ− iρ0ρ0|) (32) ͱͳͬͯɺHankelؔ਺H0(1)Λ࢖ͬͯ׬શʹදݱ͞ΕΔɻ ͜͜Ͱɺiρρ = ixx+iyy,iρ0ρ0͸ਫฏ໘(z = 0)಺ͷҐஔ ϕΫτϧͰ͋ΔɻHankelؔ਺͸ԁ౵࠲ඪʹ͓͚Δࣗ༝ۭ ؒͰͷGreenؔ਺Ͱ͋ΔͷͰɺ͜ͷ͜ͱ͔Β΋ຊNFFFT ཧ࿦ͷଥ౰ੑ͕๣ূͰ͖Α͏ɻͳ͓ɺz = 0Ҏ֎ͷਫฏ໘ ʹ͓͚Δը૾ɺͭ·Γɺ͜ͷ໘ͰͷRCSύλʔϯ͸z =ఆ ਺ ͱ͢Δ͜ͱͰٻΊΒΕΔ͜ͱ΋ཧղͰ͖ΔɻΞϯςφ ʹࢦ޲ੑ͕͋Δ৔߹͸ɺը૾ੜ੒Ҭͱϓϩʔϒ૸ࠪҬͷ ؒͷڑ཭͸ɺ2k|r−r0| ≫ 1ͷΑ͏ʹ਺೾௕Ҏ্͋Δͷ Ͱɺ઴ۙతʹධՁ͢Ε͹Α͍ɻͦ͜ͰɺఀཹҐ૬๏Λ༻ ͍ͯ઴ۙղΛٻΊΔͱɺ݁Ռ͸࣍ࣜͷΑ͏ʹͳΔɻ T _≈ ρ0e −jk|iρρ−iρ0ρ0|+jπ/4 √_πP2_(β c)√2k|iρρ− iρ0ρ0| . (33) ͜͜Ͱɺ֯౓β͸βc= ρ0χ(x, y, ϕ0)/|iρρ−iρ0ρ0|Ͱ༩͑ ΒΕΔ. ܭଌͨۙ͠๣ి࣓քEs near(k, ϕ0, z0)Λআ͍ͯɺੵ෼ (30)ͷશͯͷඃੵ෼ؔ਺͸z0ʹಠཱ͍ͯ͠Δɻैͬͯɺ ࡾ࣍ݩԁ౵૸ࠪͷNFFFTͷ࠷ऴతͳެࣜ͸࣍ࣜͰ༩͑Δ ͜ͱ͕Ͱ͖Δ: Φ(x, y) = ∫ ∞ 0 dk ∫ 2π 0

dϕ0⟨Enears (k, ϕ0)⟩ ˜F (k, ϕ0, x, y).(34)

͜͜ʹɺয఺Խؔ਺͸࣍ࣜͰఆٛ͞ΕΔ: ˜ F (k, ϕ0, x, y) = ρ2 0χ(x, y, ϕ0)ejk|iρρ−iρ0ρ0|+jπ/4 √ πE0(k)P2(βc)√2k|iρρ− iρ0ρ0| .(35) ࣜ(34)ͷܭࢉʹ͸ɺਨ௚࣠ํ޲ʹରͯ͠ฏۉԽͨۙ͠ ๣ք ⟨Es near(k, ϕ0)⟩= ∫ ∞ −∞ dz0Enears (k, ϕ0, z0) (36) Λ༻͍Δɻࣜ(28)ͱ(34)͸൒ܘρ0ͷԁप૸ࠪNFFFT ͱಉ͡ܗͱͳ͍ͬͯΔ͜ͱ͕෼͔Δɻ།Ұͷҧ͍͸য఺ Խؔ਺ͷද͚ࣔͩͰ͋Δ[10]ɻ

ͷ࠲ඪɺͦͯ͠ F (r, r0, k) = Acalχ(x, y, ϕ0) π3_Es cal(k)|r − r0| e2jk(|r−r0|)−ρ0₍₂₄₎ ͸ࡾ࣍ݩԁ౵࠲ඪܥͷয఺Խؔ਺Ͱ͋Γɺԁप૸ࠪͷ৔ ߹ͱಉ͡Α͏ʹɺ૸ࠪ໘্ͷҟͳͬͨ఺Ͱͷࢄཚքͱͷ Ґ૬ɺৼ෯ͷࠩΛิਖ਼͢Δ͜ͱ͕Ͱ͖Δɻ·্ͨࣜʹ͸ɺ ߍਖ਼࣌ͷࢄཚମ͔ΒͷσʔλEs cal(k)ʹର͢Δԕํք܎ ਺Acal(k)Λߟྀͨ͠දࣔͱ͍ͯ͠Δɻؔ਺ χ(x, y, ϕ0) = 1− x ρ0 cos ϕ0− y ρ0 sin ϕ0 (25) ͸ԁप૸ࠪͰಋೖͨ͠ิਖ਼ؔ਺Ͱ͋ΔɻҎԼɺੵ෼දࣔ ࣜ(22)ͱ(23)ʹ͍ͭͯௐ΂Δɻ ઌͣɺߍਖ਼༻ࢄཚମʹΑΔࢄཚքΛ Ecals (k) = E0(k) Acal(k) √ 4πρ2 0 e−2jkρ0 ₍₂₆₎ Ͱද͠ɺয఺Խؔ਺Λૹ৴Ξϯςφͷ։ޱ͔Βͷ์ࣹք E0(k)Ͱ༩͑Δɻ ࣍ʹɺϓϩʔϒΞϯςφͷࢦ޲ੑύλʔϯP (β)ʹͭ ͍ͯߟ͑Δɻ͜͜Ͱ͸, ૹड৴Ξϯςφ͕ಉ͡΋ͷͱ͢ Δɻ֯β ͸ΞϯςφϘΞαΠτ࣠ilͱɺ఺r0͔Βݟͨ ը૾্ͷ఺r΁ͷํ޲ͱͷؒͰ࡞ΒΕΔ֯౓Ͱ͋Δɻ͜ ͷͱ͖ɺil=−iρ0ρ0, iρ0ρ0= ixcos ϕ0+iysin ϕ0ͷؔ܎

͕ܭࢉͰ͖ɺ͜ͷ݁Ռɺয఺Խؔ਺͸࣍ࣜͷΑ͏ʹͳΔ: F (r, r0, k) = 2ρ 2 0χ(x, y, ϕ0)e2jk|r−r0| π5/2_E 0(k)P2(β)|r − r0| . (27) ্ࣜ͸఺r1 ʹ͋Δిؾతʹখ͞ͳࢄཚମΛԾఆͯ͠ɺ (24)͔ࣜΒ༠ಋ͍ͯ͠Δɻͭ·Γɺԕํք܎਺ΛA(k) ͱ͢Δͱɺdeltaؔ਺Ͱ༩͑ͨϨʔμը૾ Φ1(r) = δ(r− r1)A1(k)/k2 ͸Ξϯςφύλʔϯؔ਺P (β)ʹಠཱͯ͠ ͍ΔͷͰɺमਖ਼ͨ͠RCS஋σ1=|A1(k)|2͕ٻΊΒΕΔɻ ࠷ޙ͸(22)ࣜʹؔ͢Δ΋ͷͰɺ͜ΕΛॻ͖׵͑Δͱɺ σ(k, ϕ) = k4 � � � � ∫∫ Ω

Φ(x, y)e2jk(x cos ϕ+y sin ϕ)dxdy

� � � � 2 (28) ͱͳΔɻ͜͜ͰɺΩ͸ԁ౵૸ࠪͷਫฏஅ໘ʹ͋Δը૾ੜ ੒Ҭ(ਤ1)Ͱ͋ΓɺҰํɺΦ(x, y)͸ Φ(x, y) = ∫ ∞ −∞ Ψ(r)dz (29) Ͱఆٛ͞ΕΔɻ(27)ͱ(23)ࣜΛ(29)ࣜʹ୅ೖ͢Δͱɺ Φ(r) (30) = ∫ ∞ 0 dk ∫ 2π 0 dϕ0 ∫ ∞ −∞ dz0Enears (k, ϕ0, z0) χ(x, y, ϕ0) E0(k) T ͕ಘΒΕΔɻ͜͜Ͱɺඃੵ෼ؔ਺ͷT͸ T = 2ρ 2 0 π5/2 ∫ ∞ −∞ e2jk|r−r0| P2_{(β)|r − r} 0| dz (31) Ͱ༩͑ΒΕΔɻ ࠓɺϓϩʔϒΞϯςφ͸ແࢦ޲ੑͰ͋Δͱ͢Δͱɺ P (β) = 1Ͱ͋ΔͷͰɺ্ࣜ͸ T = 2jρ 2 0 π3/2H (1) 0 (2k|iρρ− iρ0ρ0|) (32) ͱͳͬͯɺHankelؔ਺H0(1)Λ࢖ͬͯ׬શʹදݱ͞ΕΔɻ ͜͜Ͱɺiρρ = ixx+iyy,iρ0ρ0͸ਫฏ໘(z = 0)಺ͷҐஔ ϕΫτϧͰ͋ΔɻHankelؔ਺͸ԁ౵࠲ඪʹ͓͚Δࣗ༝ۭ ؒͰͷGreenؔ਺Ͱ͋ΔͷͰɺ͜ͷ͜ͱ͔Β΋ຊNFFFT ཧ࿦ͷଥ౰ੑ͕๣ূͰ͖Α͏ɻͳ͓ɺz = 0Ҏ֎ͷਫฏ໘ ʹ͓͚Δը૾ɺͭ·Γɺ͜ͷ໘ͰͷRCSύλʔϯ͸z =ఆ ਺ ͱ͢Δ͜ͱͰٻΊΒΕΔ͜ͱ΋ཧղͰ͖ΔɻΞϯςφ ʹࢦ޲ੑ͕͋Δ৔߹͸ɺը૾ੜ੒Ҭͱϓϩʔϒ૸ࠪҬͷ ؒͷڑ཭͸ɺ2k|r−r0| ≫ 1 ͷΑ͏ʹ਺೾௕Ҏ্͋Δͷ Ͱɺ઴ۙతʹධՁ͢Ε͹Α͍ɻͦ͜ͰɺఀཹҐ૬๏Λ༻ ͍ͯ઴ۙղΛٻΊΔͱɺ݁Ռ͸࣍ࣜͷΑ͏ʹͳΔɻ T _≈ ρ0e −jk|iρρ−iρ0ρ0|+jπ/4 √_πP2_(β c)√2k|iρρ− iρ0ρ0| . (33) ͜͜Ͱɺ֯౓β͸βc= ρ0χ(x, y, ϕ0)/|iρρ−iρ0ρ0|Ͱ༩͑ ΒΕΔ. ܭଌͨۙ͠๣ి࣓քEs near(k, ϕ0, z0)Λআ͍ͯɺੵ෼ (30)ͷશͯͷඃੵ෼ؔ਺͸z0ʹಠཱ͍ͯ͠Δɻैͬͯɺ ࡾ࣍ݩԁ౵૸ࠪͷNFFFTͷ࠷ऴతͳެࣜ͸࣍ࣜͰ༩͑Δ ͜ͱ͕Ͱ͖Δ: Φ(x, y) = ∫ ∞ 0 dk ∫ 2π 0

dϕ0⟨Enears (k, ϕ0)⟩ ˜F (k, ϕ0, x, y).(34)

͜͜ʹɺয఺Խؔ਺͸࣍ࣜͰఆٛ͞ΕΔ: ˜ F (k, ϕ0, x, y) = ρ2 0χ(x, y, ϕ0)ejk|iρρ−iρ0ρ0|+jπ/4 √ πE0(k)P2(βc)√2k|iρρ− iρ0ρ0| .(35) ࣜ(34)ͷܭࢉʹ͸ɺਨ௚࣠ํ޲ʹରͯ͠ฏۉԽͨۙ͠ ๣ք ⟨Es near(k, ϕ0)⟩= ∫ ∞ −∞ dz0Enears (k, ϕ0, z0) (36) Λ༻͍Δɻࣜ(28)ͱ(34)͸൒ܘρ0ͷԁप૸ࠪNFFFT ͱಉ͡ܗͱͳ͍ͬͯΔ͜ͱ͕෼͔Δɻ།Ұͷҧ͍͸য఺ Խؔ਺ͷද͚ࣔͩͰ͋Δ[10]ɻ ਤ5 ԁ౵૸ࠪNFFFTॲཧιϑτ΢ΣΞγεςϜ:KOSIP:૸ࠪػߏܥͱϚΠΫϩ೾ܭଌܥͷιϑτ΢ΣΞ੍ޚ,ը૾ੜ੒ॲ ཧ,ԕํRCS/ΞϯςφύλʔϯධՁ

Fig.5 KOSIP Software code system as controller equipment for cylindrical scanning NFFFT.

Ҏ্ͰಘΒΕͨ(28),(34),(35),(36)ࣜ͸ɺz͓Αͼ z0ʹؔ͢Δੵ෼ͷඞཁੑ͸ͳ͍ͷͰɺԁ౵૸ࠪͰ΋େ෯ ͳNFFFTॲཧ࣌ؒͷվળ͕ݟࠐ·ΕΔɻฏۉॲཧΛߦͬ ͨి࣓ք(36)͸୯ʹ૸ࠪ໘z-࣠ʹԊͬͯσʔλΛऩू ͢Δ͚ͩͰٻΊΒΕΔɻߍਖ਼ܭଌͷE0(k)प೾਺ಛੑ ͸ɺಋମٿ͋Δ͍͸ฏ൘ͳͲԕํք܎਺Acal(k)͕ط஌ ͷࢄཚମͷܭଌ͔Β(26)ࣜΛ࢖ͬͯٻΊΒΕΔɻҰ୴ E0(k)͕෼͔Ε͹ɺॴཁͷप೾਺ଳҬͱ૸ࠪεςοϓΛ ߟྀͯ͠ɺඃܭଌ෺ͷࢄཚքΛ࣮ଌ͢Ε͹Α͍ɻ 4.ԁ౵૸ࠪίʔυKOSIPͷ։ൃͱܭଌ݁Ռ ਤ5ʹࣔ͢ϒϩοΫߏ੒ΛجʹɺϚΠΫϩ೾ωοτϫʔ ΫΞφϥΠβͱ૸ࠪػߏܥͷ੍ޚ͠ɺऔಘͨ͠Ұ࿈ͷૹ ड৴σʔλ͔ΒRCSΛٻΊΔධՁι΢τ΢ΣΞ(KOSIP ͱ໋໊)Λࢼ࡞։ൃͨ͠ɻϓϩάϥϜݴޠ͸ਤͷੜ੒͕ ༰қͰɺଌఆثͱͷΠϯλʔϑΣʔε͕ศརͳMATLAB Λ࠾༻͍ͯ͠Δɻ͜ͷࢼ࡞։ൃͨ͠ιϑτ΢ΣΞίʔυ KOSIP͸ɺେ͖͘4ݸͷ΢Πϯυ΢: (1)ܭଌɺ(2)ߍਖ਼ɺ (3)γϛϡϨʔγϣϯɺ(4) RCSධՁ͔Βߏ੒͞ΕΔɻਤ 6͸͜ͷ಺ͷ(1)ܭଌϞʔυͷ΢Οϯυ΢Ͱ͋ΔɻҎԼɺ ͦͷ֓ཁʹ͍ͭͯهड़͢Δɻ (1) ͷܭଌϞʔυͰ͸ɺप೾਺ͳͲͷύϥϝʔλΛ ೖ ྗ ͠, ϕ Ϋ τ ϧ ω ο τ ϫ ʔ Ϋ Ξ φ ϥ Π β (VNA) ͓ Α ͼ Ϟ ʔ λ ʔ ૸ ࠪ ܥ Λ ੍ ޚ ͠ ͯ ࣮ ࡍ ʹ ࢄ ཚ ք Λ ܭ ଌ ͠ɺऔಘσʔλΛϝϞϦʔʹ֨ೲ͢Δɻσʔλͷ୯Ґ ͸(dB)Ͱ͋Δɻ(2) ͷߍਖ਼ॲཧͷ݁ՌΛऔΓೖΕͯɺ (dB square meter: dBsm)ʹ͢Δɻ͜ͷաఔ͸(4)ͷRCS ධՁϞʔυͰߦ͏ɻ(3)ͷγϛϡϨʔγϣϯϞʔυͰ͸ɺ ಋମٿɺಋମฏ൘ɺೋ໘ͱࡾ໘ͷίʔφʔϦϑϨΫλͳ Ͳجຊܗঢ়ͷࢄཚମʹΑΔNFFFTͷཧ࿦ܭࢉΛߦ͏͜ͱ ͕Ͱ͖ΔɻಉίʔυͰ͸ɺ͜ΕΒͷࢄཚମͷۙ๣ͱԕํ ͷࢄཚքܭࢉࣜΛඋ͍͑ͯΔɻ͞ΒʹɺϓϩʔϒΞϯς φͷิਖ਼ͷͨΊɺμΠϙʔϧɺ֯ਲ਼ϗʔϯͳͲͷཧ࿦ܭ ࢉϢχοτ΋ซඋ͍ͯ͠Δɻ NFFFT૯߹ॲཧίʔυ: KOSIP͸ɺᒬʑͳػೳͱརศੑ Λߟྀͯ͠։ൃͨ͠ɻຊ࿦Ͱ͸৮Ε͍ͯͳ͍͕ɺϞϊε λςΟοΫͷϨʔμϞʔυͷଞʹόΠελςΟοΫϞʔ υͰͷܭଌʹ΋ରॲ͍ͯ͠Δɻٯ߹੒։ޱϨʔμ(ISAR) ॲཧͰ͸ɺࡾ࣍ݩը૾ΛఏڙͰ͖Δɻલઅ·Ͱͷཧ࿦ݕ ূͰྨਪՄೳͰ͋Δ͕ɺࢄཚύλʔϯΛੜ੒͢ΔϚΠΫ

ਤ6 ԁ౵૸ࠪRCS૯߹ධՁίʔυKOSIP:ଌఆϞʔυͷGUI΢Οϯυ΢ྫ

Fig.6 KOSIP GUI for RCS comprehensive evaluation system in cylindrical scanning NFFFT: measurement-mode opening window.

ϩ೾ը૾͕ͲͷΑ͏ͳର৅෺͔͸ɺجຊతʹෆ໰Ͱ͋Δɻ ͜ͷ͜ͱ͸ผܭଌͰऔಘͨ͠ϚΠΫϩ೾ෳૉը૾Ͱ͋Γ ͑͢͞Ε͹ɺͦͷࢄཚύλʔϯΛม׵Ͱ͖Δ͜ͱΛࣔࠦ ͍ͯ͠Δɻ஍Լຒઃ෺͋Δ͍͸นಁաͷը૾͔ΒɺͲͷ Α͏ͳύλʔϯ͕ಘΒΕΔ͔͸ڵຯͷ༙͘τϐοΫͰ΋ ͋ΔɻҰํɺطʹ৮Ε͍ͯΔΑ͏ʹɺిؾతʹ༗ݶͷڑ ཭ͰͷRCSύλʔϯ΋ࢉग़Ͱ͖Δɻࣗಈंিಥ๷ࢭ༻ͷ ۙڑ཭Ϩʔμ౳ʹ͓͚Δલํࢄཚ෺ͷ൓ࣹஅ໘ੵͷධՁ Ͱ͸ɺॏཁͳ߲໨ͱͳΓ͑Δɻࠓޙɺৄࡉݕ౼ͷ༧ఆͰ ͋Δɻ RCS͸ͦͷ໊ͷࣔ͢௨Γૹड৴ػೳΛ΋ͭϨʔμʹର ͢Δࢄཚ౓߹͍ͷࢦඪͰ͋ΔɻैͬͯɺRCSܭଌ͸2-way ͕ݪଇͱͳΔɻଞํɺΞϯςφͷܭଌ͸جຊతʹ1-way Ͱ͋ΔɻϗʔϯΞϯςφͳͲΛྫʹͱΔͱɺ։ޱ໘ͷۙ ๣ి࣓ք෼෍͕෼͔Ε͹ɺԕํ์ࣹքΛཧ࿦తʹٻΊΔ ͜ͱ͕Ͱ͖Δɻਤ5ʹࣔ͢Α͏ʹɺNFFFTܭଌ͸ೋͭͷ ϓϩʔϒΞϯςφͰ2-wayRCSܭଌΛߦ͏ํ๏Ͱ͋Δ͕ɺ ͜ͷҰํͷϓϩʔϒ(ૹ৴)ΛඃܭଌͷΞϯςφͷڅి୺ ʹ઀ଓ͢ΔͱɺΞϯςφͷۙ๣քʹΑΔը૾͕ੜ੒͞Ε Δɻޙड़͢ΔΑ͏ʹɺͦͷԕํม׵ͷ݁Ռ͸͍ΘΏΔΞ ϯςφͷԕํύλʔϯͱͳΔɻ KOSIPίʔυͷγϛϡϨʔγϣϯϞʔυΛ༻͍ͯɺখ ͞ͳෳ਺ݸͷಋମٿΛϞσϧʹͨ͠جૅతͳཧ࿦ݕূྫ Λਤ7,8ʹࣔ͢ɻਤ7͸ɺ_{|x| ≤ 0.5, y = z = 0}ͷ౳ִؒͰ ഑ஔͨ͠11ݸͷখ͞ͳಋମٿͷ৔߹Ͱ͋Δɻٿͷ൒ܘ͸ ͢΂ͯ1.0 cm = 1/30 λ, f = 1 GHzͱ͍ͯ͠Δɻٿಉ࢜ͷ ִؒϐον͸_{10 cm = 1/3λ}Ͱ͋ΔͨΊɺٿͷҰྻ͸ࡉ͍ ฏ൘(௚ઢ)ͷΑ͏ʹৼΔ෣͏ͱ༧૝Ͱ͖Δɻಉਤͷ݁Ռ ͸ฏ൘͔ΒͷࢄཚಛੑΛ͓ࣔͯ͠Γɺଥ౰ੑ͕͋Δͱ൑ அͰ͖Δɻͳ͓ɺ͜ͷ݁Ռ͸ݫີղͱ΋׬શʹҰகͯ͠ ͍Δ͜ͱΛ֬ೝ͍ͯ͠Δɻ ਤ8 ͸ ൒ ܘ ͷ ҟ ͳ Δ 4 ݸ ͷ ಋ ମ ٿ ʹ Α Δ ཧ ࿦ RCS Ͱ͋Γɺप೾਺͸ f = 3 GHz ͱ͍ͯ͠Δɻٿͷ࠲ඪͱ ൒ܘ͸#1(50, 0, 0),r1= 0.1,#2(−25, 43, 0),r2= 0.8, #3(_{−25, −43, 0),r}3= 0.8,#4(−25, 0, 50),r4= 0.5 cmͰ ͋ Δ ɻͦ ͷ ଞ ͷ ύ ϥ ϝ ʔ λ ͸ ɺத ৺ प ೾ ਺ ͸ 3 GHzɺ ଳҬ෯͸ 1.0 GHzɺप೾਺εςοϓ͸57.7 MHzɺρ0 = 150 cm, δϕ0 = 1◦ɺը ૾ ͷ ϐ Ϋ η ϧ α Π ζ ͸ 0.7 cmɺ (zmax, zmin, δz) = (20,_{−52, 3.5) cm}ͱ͍ͯ͠ΔɻNFFFT ʹΑΔ͜ͷRCS݁Ռ͸ɺݫີղͱ΄΅Ұக͍ͯ͠Δɻ ͯ࣍͞ʹɺNFFFTʹΑΔ RCS ධՁίʔυΛ༻͍࣮ͨ ଌ݁Ռʹ͍ͭͯٞ࿦͢Δɻਤ9͓Αͼ10͸ɺ֤ʑ௚ܘ 10 cmͷಋମٿͱ։ޱͷҰล͕10 cmͷࡾ໘ίʔφʔϦϑ ϨΫλΛඃଌఆ෺ͱͯ͠ɺ։ൃίʔυKOSIPʹΑΓܭଌ ͨ͠Ϩʔμը૾ͱԕํม׵RCSͷ݁ՌͰ͋Δɻܭଌप೾ ਺ൣғͱεςοϓ͸֤ʑ5.0 - 6.0 GHzɺ10 MHzͰ͋Δɻϓ

ਤ6 ԁ౵૸ࠪRCS૯߹ධՁίʔυKOSIP:ଌఆϞʔυͷGUI΢Οϯυ΢ྫ

Fig.6 KOSIP GUI for RCS comprehensive evaluation system in cylindrical scanning NFFFT: measurement-mode opening window.

ϩ೾ը૾͕ͲͷΑ͏ͳର৅෺͔͸ɺجຊతʹෆ໰Ͱ͋Δɻ ͜ͷ͜ͱ͸ผܭଌͰऔಘͨ͠ϚΠΫϩ೾ෳૉը૾Ͱ͋Γ ͑͢͞Ε͹ɺͦͷࢄཚύλʔϯΛม׵Ͱ͖Δ͜ͱΛࣔࠦ ͍ͯ͠Δɻ஍Լຒઃ෺͋Δ͍͸นಁաͷը૾͔ΒɺͲͷ Α͏ͳύλʔϯ͕ಘΒΕΔ͔͸ڵຯͷ༙͘τϐοΫͰ΋ ͋ΔɻҰํɺطʹ৮Ε͍ͯΔΑ͏ʹɺిؾతʹ༗ݶͷڑ ཭ͰͷRCSύλʔϯ΋ࢉग़Ͱ͖Δɻࣗಈंিಥ๷ࢭ༻ͷ ۙڑ཭Ϩʔμ౳ʹ͓͚Δલํࢄཚ෺ͷ൓ࣹஅ໘ੵͷධՁ Ͱ͸ɺॏཁͳ߲໨ͱͳΓ͑Δɻࠓޙɺৄࡉݕ౼ͷ༧ఆͰ ͋Δɻ RCS͸ͦͷ໊ͷࣔ͢௨Γૹड৴ػೳΛ΋ͭϨʔμʹର ͢Δࢄཚ౓߹͍ͷࢦඪͰ͋ΔɻैͬͯɺRCSܭଌ͸2-way ͕ݪଇͱͳΔɻଞํɺΞϯςφͷܭଌ͸جຊతʹ1-way Ͱ͋ΔɻϗʔϯΞϯςφͳͲΛྫʹͱΔͱɺ։ޱ໘ͷۙ ๣ి࣓ք෼෍͕෼͔Ε͹ɺԕํ์ࣹքΛཧ࿦తʹٻΊΔ ͜ͱ͕Ͱ͖Δɻਤ5ʹࣔ͢Α͏ʹɺNFFFTܭଌ͸ೋͭͷ ϓϩʔϒΞϯςφͰ2-wayRCSܭଌΛߦ͏ํ๏Ͱ͋Δ͕ɺ ͜ͷҰํͷϓϩʔϒ(ૹ৴)ΛඃܭଌͷΞϯςφͷڅి୺ ʹ઀ଓ͢ΔͱɺΞϯςφͷۙ๣քʹΑΔը૾͕ੜ੒͞Ε Δɻޙड़͢ΔΑ͏ʹɺͦͷԕํม׵ͷ݁Ռ͸͍ΘΏΔΞ ϯςφͷԕํύλʔϯͱͳΔɻ KOSIPίʔυͷγϛϡϨʔγϣϯϞʔυΛ༻͍ͯɺখ ͞ͳෳ਺ݸͷಋମٿΛϞσϧʹͨ͠جૅతͳཧ࿦ݕূྫ Λਤ7,8ʹࣔ͢ɻਤ7͸ɺ_{|x| ≤ 0.5, y = z = 0}ͷ౳ִؒͰ ഑ஔͨ͠11ݸͷখ͞ͳಋମٿͷ৔߹Ͱ͋Δɻٿͷ൒ܘ͸ ͢΂ͯ1.0 cm = 1/30 λ, f = 1 GHzͱ͍ͯ͠Δɻٿಉ࢜ͷ ִؒϐον͸_{10 cm = 1/3λ}Ͱ͋ΔͨΊɺٿͷҰྻ͸ࡉ͍ ฏ൘(௚ઢ)ͷΑ͏ʹৼΔ෣͏ͱ༧૝Ͱ͖Δɻಉਤͷ݁Ռ ͸ฏ൘͔ΒͷࢄཚಛੑΛ͓ࣔͯ͠Γɺଥ౰ੑ͕͋Δͱ൑ அͰ͖Δɻͳ͓ɺ͜ͷ݁Ռ͸ݫີղͱ΋׬શʹҰகͯ͠ ͍Δ͜ͱΛ֬ೝ͍ͯ͠Δɻ ਤ8 ͸ ൒ ܘ ͷ ҟ ͳ Δ 4 ݸ ͷ ಋ ମ ٿ ʹ Α Δ ཧ ࿦ RCS Ͱ͋Γɺप೾਺͸ f = 3 GHz ͱ͍ͯ͠Δɻٿͷ࠲ඪͱ ൒ܘ͸ #1(50, 0, 0),r1 = 0.1,#2(−25, 43, 0),r2= 0.8, #3(_{−25, −43, 0),r}3= 0.8,#4(−25, 0, 50),r4= 0.5 cmͰ ͋ Δ ɻͦ ͷ ଞ ͷ ύ ϥ ϝ ʔ λ ͸ ɺத ৺ प ೾ ਺ ͸ 3 GHzɺ ଳҬ෯͸ 1.0 GHzɺप೾਺εςοϓ͸57.7 MHzɺρ0 = 150 cm, δϕ0 = 1◦ɺը ૾ ͷ ϐ Ϋ η ϧ α Π ζ ͸ 0.7 cmɺ (zmax, zmin, δz) = (20,_{−52, 3.5) cm}ͱ͍ͯ͠ΔɻNFFFT ʹΑΔ͜ͷRCS݁Ռ͸ɺݫີղͱ΄΅Ұக͍ͯ͠Δɻ ͯ࣍͞ʹɺNFFFTʹΑΔ RCS ධՁίʔυΛ༻͍࣮ͨ ଌ݁Ռʹ͍ͭͯٞ࿦͢Δɻਤ9͓Αͼ10͸ɺ֤ʑ௚ܘ 10 cmͷಋମٿͱ։ޱͷҰล͕10 cmͷࡾ໘ίʔφʔϦϑ ϨΫλΛඃଌఆ෺ͱͯ͠ɺ։ൃίʔυKOSIPʹΑΓܭଌ ͨ͠Ϩʔμը૾ͱԕํม׵RCSͷ݁ՌͰ͋Δɻܭଌप೾ ਺ൣғͱεςοϓ͸֤ʑ5.0 - 6.0 GHzɺ10 MHzͰ͋Δɻϓ ਤ7 KOSIPγϛϡϨʔγϣϯϞʔυͰͷ11ݸͷಋମٿ ʹΑΔNFFFT-RCS

Fig.7 KOSIP Simulation-mode: 11-sphere, r=1 cm, 1 GHz.

ਤ8 KOSIPγϛϡϨʔγϣϯϞʔυͰͷ4ݸͷಋମٿʹ

ΑΔNFFFT-RCS

Fig.8 KOSIP Simulation-mode: 4-sphere, 3 GHz.

ϩʔϒͷ૸ࠪ൒ܘ͸1.2 mɺz-࣠૸ࠪ͸2.0 cmεςοϓ Ͱ_{±20 cm}ɺํҐํ޲ͷ֯౓εςοϓ͸1.0◦ _Ͱ͋Δɻը ૾ੜ੒Ҭ͸ρmax= 50.0 cmͰ͋ΓɺͦͷϐΫηϧαΠζ ͸1.0 mmͱ͍ͯ͠Δɻ͜͜Ͱͷ࣮ଌྫͰ͸ɺૹड৴Ξϯ ςφؒͷ௚઀೾আڈΛߴ଎ϑʔϦΤม׵(FFT)ʹͯߦͬ ͍ͯΔ(KOSIPίʔυ͸FFTॲཧϢχοτΛ༧Ί࣮૷ࡁ Έ)ɻਤ10ͷม׵ύλʔϯʹ͸ίʔφʔϦϑϨΫλͷಛ ௃͕ݱΕ͍ͯΔɻίʔφʔϦϑϨΫλͷܭଌʹؔͯ͠͸ɺ ԕํྖҬͷߟ࡯ʹ෇ਵͯ͠ޙͰৄ͘͠ݕ౼͢Δɻ ਤ9 ಋମٿͷ࣮ଌ:ԁ౵૸ࠪ, 5.5 GHz Fig.9 Measurement and NFFFT for a conducting

sphere by KOSIP code, 5.5 GHz.

ਤ10 ࡾ໘ίʔφʔϦϑϨΫλͷ࣮ଌ

Fig.10 Measuremen of 3-faces corner-reflector, cylindrical scanning, 5.5 GHz. ਤ11͸प೾਺:5.5 GHzɺଳҬ෯:1.0 GHzɺप೾਺εςο ϓ:10 MHzͰͷಋిੑృྉΛ࢖༻ͨ͠ϓϥϞσϧͷଌఆ ݁ՌͰ͋ΔɻํҐ֯ͱਨ௚ํ޲ͷ૸ࠪεςοϓ͸1.0◦ ͱ2.0 cmʢ0.37 λ)ɺϓϩʔϒڑ཭͸ρ0= 110 cmͰ͋Δɻ ը૾ྖҬͱϐΫηϧαΠζ͸ɺͦΕͧΕρmax= 50 cmͱ 0.1 mmͱ͍ͯ͠Δɻ NFFFTޙͷRCSύλʔϯͷ྆ଆ͸ ରশͰ͋Γɺϕ = 0◦͸γϟτϧϞσϧͷػटํ޲Ͱ͋Γɺ ࠷େ௕͸370 mm(6.8λ)Ͱ͋ΔɻϨʔμը૾͸ɺऔಘۙ๣ σʔλʹൺ΂ͯվળ͞Ε͍ͯΔɻྫ͑͹ɺૹ৴͔Βड৴ Ξϯςφ΁ͷ௚઀೾Λআڈ͢ΔͨΊʹFFTʹΑͬͯॲཧ ͠ɺλʔήοτ෺ମΛஔ͔ͳ͍Ͱଌఆͨ͠ը૾σʔλʹ Αͬͯࠩ͠Ҿ͘ॲཧ͕͋Δɻલऀ͸໌Β͔ʹࡾ࣍ݩࢄཚ σʔλΛแؚ͍ͯ͠ΔͨΊɺԁ౵ܗͷ૸ࠪσʔλ͸ԁܗ ΑΓ΋༗ޮͰ͋Δɻͳ͓ɺಋମٿͳͲRCSط஌ͱͷൺֱ

ߍਖ਼͸লུ͍ͯ͠ΔͷͰɺRCSύλʔϯ͸૬ରతͳdB ͷ··Ͱ͋Δɻਤ12͸KOSIPγϛϡϨʔγϣϯϞʔυ Ͱͷෳ਺ͷখ͞ͳٿʹΑΔཧ࿦తͳRCSύλʔϯΛࣔ͠ ͍ͯΔɻλʔήοτϞσϧ͸310ݸͷٿͰܗ੒͞Εͨε ϖʔεγϟτϧͷྠֲͰ͋Δɻ͜ͷখ͞ͳಋମٿʹΑΔ γϛϡϨʔγϣϯͰ͸ɺଟॏ൓ࣹ͸ߟྀ͞Ε͓ͯΒͣɺٿ ؒͷ૬ޓ࡞༻͸؍ଌͰ͖ͳ͍ɻͦͷͨΊɺܭࢉ݁Ռͷύ λʔϯ͸ɺਤ11Ͱͷ࣮ଌNFFFTύλʔϯͱ͸΍΍ҟͳͬ ͍ͯΔɻ͜ΕΛվળ͢Δํ๏ͱͯ͠ɺஶऀ͸ݱࡏɺࢦ޲ ੑͱ൓ࣹ܎਺Λߟྀͨ͠఺೾ݯͷ਺ֶϞσϧΛݚڀͯ͠ ͍Δɻࠓޙɺެදͷ༧ఆͰ͋Δɻ લड़Ͱ৮Εͨ௨ΓɺΞϯςφύλʔϯ͸1-wayͷRCS ܭଌͱͯ͠NFFFTʹΑͬͯ΋ଌఆՄೳͰ͋ΔɻඃܭଌΞ ϯςφΛճస࣠ͷத৺ʹऔΓ෇͚ɺRCSૹ৴ͷ୅ΘΓʹ Ξϯςφ୺ʹߴप೾৴߸Λೖྗ͢ΔɻಘΒΕΔۙ๣Ҭۙ ลͷϨʔμը૾͸Ξϯςφͷ։ޱి࣓ք෼෍ͱ౳ՁతͰ ͋Δͱߟ͑Δɻ͜͏ͯ͠ಘΒΕͨΞϯςφԕํύλʔϯ ͱཧ࿦ܭࢉ஋ͷൺֱΛਤ13ʹࣔ͢ɻΞϯςφ։ޱੇ๏͸ 60.0×35.0 mmɺϓϩʔϒҐஔ͸Ξϯςφ։ޱ͔Β400 mm ͷҐஔʹ͋Γɺܭଌप೾਺͸5.0 - 6.0 GHzͰ͋Δɻಉਤ ͸ԁप૸ࠪͷม׵݁ՌͰ͋ΔͷͰɺԁ౵૸ࠪͰ͸͞Βʹ ਖ਼֬ͳଌఆ݁ՌʹͳΔͱ༧૝͍ͯ͠Δɻ ͜ͷઅͷ࠷ޙʹɺNFFFTʹؔ࿈͢Δز͔ͭͷܭଌ্ͷ ཹҙࣄ߲ΛҎԼʹ͓ࣔͯ͘͠ɻ (1)ϞϊελςοΫϞʔυʹ͓͚Δೋͭͷૹड৴ϓ ϩʔϒΞϯςφͷִؒɿ ૹ৴೾มௐʹ࿈ଓ೾ʢCW)Λ࠾ ༻͍ͯ͠Δ৔߹ɺड৴ث͸ૹ৴Ξϯςφ͔Βͷ௚઀ిྗ ΑΓ΋খ͍͞λʔήοτ͔Βͷ൓ࣹ೾Λड৴͢Δ͜ͱ͸ Ͱ͖ͳ͍ɻૹ৴Ξϯςφ͔Βड৴Ξϯςφ΁ͷ৴߸෼཭ ౓͸͜ͷ࠷௿Ϩϕϧ͔Βܾఆ͞Εɺ͜Ε͸ΞϯςφλΠ ϓͱִؒઃఆํ๏ʹґଘ͢Δɻ Ұํɺִؒͷେ͖͞͸ β < λ/D∥Λอূ͢Δඞཁ͕͋Δɻ͜͜Ͱɺβ͸όΠελ ςΟοΫ෼཭֯౓Ͱ͋ΓɺD∥͸ਫฏํ޲ͷλʔήοτͷ ࠷େαΠζͰ͋ΔɻೋͭͷΞϯςφ͕ਨ௚ํ޲ʹ഑ஔ͞ Ε͍ͯΔ৔߹ɺ͜ͷͱ͖ͷ৚݅ࣜ͸β<λ/D_⊥ͰධՁ͞Ε Δɻ͜͜ͰɺD_⊥͸ਨ௚ํ޲ʹ͓͚Δλʔήοτͷ࠷େα ΠζͰ͋Δɻ (2)ܭଌܥϨϕϧνϟʔτ:ਤ14ʹࣔ͢Α͏ʹɺॴཁ ͷS/N ൺͱμΠφϛοΫϨϯδΛҡ࣋͢Δ͜ͱ͸ɺ࣮ ࡍͷଌఆ؀ڥͰ͸ۃΊͯॏཁͰ͋Δɻ͜Ε͸ओʹೋͭͷ Ξϯςφؒͷ෼཭౓ͱి೾҉ࣨͷੑೳʹґଘ͢Δɻܭଌ ܥͷμΠφϛοΫϨϯδͱS/NൺʹԠͯ͡ɺΞΠιϨʔ γϣϯ͕͓͓Αͦ30dBະຬͷ৔߹͸ɺύϧεϞʔυͰ ਤ11 ಋిృྉ෇ϓϥενοΫϞσϧͷ࣮ଌ

Fig.11 Measurement of plastic-model with con-ducting paint, cylindrical scanning, 5.5 GHz.

ਤ12 ଟ਺ͷٿͰ࡞੒ͨ͠γϟτϧϞσϧͷϨʔμը૾ ͱRCS

Fig.12 Radar image and RCS pattern of the space-shuttle modelled by multiple small spheres.

ͷܭଌ͕ඞཁͱͳΔ͜ͱ΋͋Δɻ͞Βʹ௕࣌ؒͷଌఆͰɺ ϕΫτϧωοτϫʔΫΞφϥΠβ(VNA)͸ܭଌ஋͕ॳظ ஋͔ΒͣΕΔ͜ͱ͕͋ΔͷͰɺܭଌ։࢝ͷҐ૬ͱৼ෯Λ อ࣋͢ΔͨΊɺҰఆͷִ࣌ؒؒΛܦͯߍਖ਼͕ඞཁͱͳΔɻ (3)ճసத৺:ඃܭଌ෺ͷλʔήοτ͕ٿͷΑ͏ͳର৅ ෺Ͱ͋Δ৔߹ɺͦͷ෺ཧతத৺Λػցతճసத৺ʹՄೳ ͳݶΓҰகͤ͞Δඞཁ͕͋Δɻ ʢ4ʣNFFFTܭଌͱ҉ࣨͷ੔߹:λʔήοτपғͷ҉ࣨ ΫϫΠΤοτκʔϯΛઃܭ͢Δ৔߹ɺNFFFTϚΠΫϩ೾ ܭଌܥͱ҉ࣨ؀ڥͷ෼཭ઃܭ͸ආ͚Δ΂͖Ͱ͋ΔɻͦΕ Ͱ΋ɺߴੑೳͷΫϫΠΤοτκʔϯ͸ඞཁͳ͍ͱߟ͑Δɻ NFFFTϓϩʔϒΞϯςφ͸લํ෇ۙʹ഑ஔ͞Ε͍ͯΔͨ

ߍਖ਼͸লུ͍ͯ͠ΔͷͰɺRCSύλʔϯ͸૬ରతͳdB ͷ··Ͱ͋Δɻਤ12͸KOSIPγϛϡϨʔγϣϯϞʔυ Ͱͷෳ਺ͷখ͞ͳٿʹΑΔཧ࿦తͳRCSύλʔϯΛࣔ͠ ͍ͯΔɻλʔήοτϞσϧ͸310ݸͷٿͰܗ੒͞Εͨε ϖʔεγϟτϧͷྠֲͰ͋Δɻ͜ͷখ͞ͳಋମٿʹΑΔ γϛϡϨʔγϣϯͰ͸ɺଟॏ൓ࣹ͸ߟྀ͞Ε͓ͯΒͣɺٿ ؒͷ૬ޓ࡞༻͸؍ଌͰ͖ͳ͍ɻͦͷͨΊɺܭࢉ݁Ռͷύ λʔϯ͸ɺਤ11Ͱͷ࣮ଌNFFFTύλʔϯͱ͸΍΍ҟͳͬ ͍ͯΔɻ͜ΕΛվળ͢Δํ๏ͱͯ͠ɺஶऀ͸ݱࡏɺࢦ޲ ੑͱ൓ࣹ܎਺Λߟྀͨ͠఺೾ݯͷ਺ֶϞσϧΛݚڀͯ͠ ͍Δɻࠓޙɺެදͷ༧ఆͰ͋Δɻ લड़Ͱ৮Εͨ௨ΓɺΞϯςφύλʔϯ͸1-wayͷRCS ܭଌͱͯ͠NFFFTʹΑͬͯ΋ଌఆՄೳͰ͋ΔɻඃܭଌΞ ϯςφΛճస࣠ͷத৺ʹऔΓ෇͚ɺRCSૹ৴ͷ୅ΘΓʹ Ξϯςφ୺ʹߴप೾৴߸Λೖྗ͢ΔɻಘΒΕΔۙ๣Ҭۙ ลͷϨʔμը૾͸Ξϯςφͷ։ޱి࣓ք෼෍ͱ౳ՁతͰ ͋Δͱߟ͑Δɻ͜͏ͯ͠ಘΒΕͨΞϯςφԕํύλʔϯ ͱཧ࿦ܭࢉ஋ͷൺֱΛਤ13ʹࣔ͢ɻΞϯςφ։ޱੇ๏͸ 60.0×35.0 mmɺϓϩʔϒҐஔ͸Ξϯςφ։ޱ͔Β400 mm ͷҐஔʹ͋Γɺܭଌप೾਺͸5.0 - 6.0 GHzͰ͋Δɻಉਤ ͸ԁप૸ࠪͷม׵݁ՌͰ͋ΔͷͰɺԁ౵૸ࠪͰ͸͞Βʹ ਖ਼֬ͳଌఆ݁ՌʹͳΔͱ༧૝͍ͯ͠Δɻ ͜ͷઅͷ࠷ޙʹɺNFFFTʹؔ࿈͢Δز͔ͭͷܭଌ্ͷ ཹҙࣄ߲ΛҎԼʹ͓ࣔͯ͘͠ɻ (1)ϞϊελςοΫϞʔυʹ͓͚Δೋͭͷૹड৴ϓ ϩʔϒΞϯςφͷִؒɿ ૹ৴೾มௐʹ࿈ଓ೾ʢCW)Λ࠾ ༻͍ͯ͠Δ৔߹ɺड৴ث͸ૹ৴Ξϯςφ͔Βͷ௚઀ిྗ ΑΓ΋খ͍͞λʔήοτ͔Βͷ൓ࣹ೾Λड৴͢Δ͜ͱ͸ Ͱ͖ͳ͍ɻૹ৴Ξϯςφ͔Βड৴Ξϯςφ΁ͷ৴߸෼཭ ౓͸͜ͷ࠷௿Ϩϕϧ͔Βܾఆ͞Εɺ͜Ε͸ΞϯςφλΠ ϓͱִؒઃఆํ๏ʹґଘ͢Δɻ Ұํɺִؒͷେ͖͞͸ β < λ/D∥Λอূ͢Δඞཁ͕͋Δɻ͜͜Ͱɺβ͸όΠελ ςΟοΫ෼཭֯౓Ͱ͋ΓɺD∥͸ਫฏํ޲ͷλʔήοτͷ ࠷େαΠζͰ͋ΔɻೋͭͷΞϯςφ͕ਨ௚ํ޲ʹ഑ஔ͞ Ε͍ͯΔ৔߹ɺ͜ͷͱ͖ͷ৚݅ࣜ͸β<λ/D_⊥ͰධՁ͞Ε Δɻ͜͜ͰɺD_⊥͸ਨ௚ํ޲ʹ͓͚Δλʔήοτͷ࠷େα ΠζͰ͋Δɻ (2)ܭଌܥϨϕϧνϟʔτ:ਤ14ʹࣔ͢Α͏ʹɺॴཁ ͷS/N ൺͱμΠφϛοΫϨϯδΛҡ࣋͢Δ͜ͱ͸ɺ࣮ ࡍͷଌఆ؀ڥͰ͸ۃΊͯॏཁͰ͋Δɻ͜Ε͸ओʹೋͭͷ Ξϯςφؒͷ෼཭౓ͱి೾҉ࣨͷੑೳʹґଘ͢Δɻܭଌ ܥͷμΠφϛοΫϨϯδͱS/NൺʹԠͯ͡ɺΞΠιϨʔ γϣϯ͕͓͓Αͦ30dBະຬͷ৔߹͸ɺύϧεϞʔυͰ ਤ11 ಋిృྉ෇ϓϥενοΫϞσϧͷ࣮ଌ

Fig.11 Measurement of plastic-model with con-ducting paint, cylindrical scanning, 5.5 GHz.

ਤ12 ଟ਺ͷٿͰ࡞੒ͨ͠γϟτϧϞσϧͷϨʔμը૾ ͱRCS

Fig.12 Radar image and RCS pattern of the space-shuttle modelled by multiple small spheres.

ͷܭଌ͕ඞཁͱͳΔ͜ͱ΋͋Δɻ͞Βʹ௕࣌ؒͷଌఆͰɺ ϕΫτϧωοτϫʔΫΞφϥΠβ(VNA)͸ܭଌ஋͕ॳظ ஋͔ΒͣΕΔ͜ͱ͕͋ΔͷͰɺܭଌ։࢝ͷҐ૬ͱৼ෯Λ อ࣋͢ΔͨΊɺҰఆͷִ࣌ؒؒΛܦͯߍਖ਼͕ඞཁͱͳΔɻ (3)ճసத৺:ඃܭଌ෺ͷλʔήοτ͕ٿͷΑ͏ͳର৅ ෺Ͱ͋Δ৔߹ɺͦͷ෺ཧతத৺Λػցతճసத৺ʹՄೳ ͳݶΓҰகͤ͞Δඞཁ͕͋Δɻ ʢ4ʣNFFFTܭଌͱ҉ࣨͷ੔߹:λʔήοτपғͷ҉ࣨ ΫϫΠΤοτκʔϯΛઃܭ͢Δ৔߹ɺNFFFTϚΠΫϩ೾ ܭଌܥͱ҉ࣨ؀ڥͷ෼཭ઃܭ͸ආ͚Δ΂͖Ͱ͋ΔɻͦΕ Ͱ΋ɺߴੑೳͷΫϫΠΤοτκʔϯ͸ඞཁͳ͍ͱߟ͑Δɻ NFFFTϓϩʔϒΞϯςφ͸લํ෇ۙʹ഑ஔ͞Ε͍ͯΔͨ ਤ13 NFFFTίʔυʹΑΔ1-way RCSͱͯ͠ͷΞϯςφύλʔϯม׵ܭଌ, ͓Αͼཧ࿦஋ͱͷൺֱ:ԁप૸ࠪ,5.5 GHz

Fig.13 Measurement of antenna pattern as 1-way RCS and comparison with theoretical result, cylindrical scanning,5.5 GHz.

ਤ14 ϚΠΫϩ೾Ϩϕϧνϟʔτ:ૹ৴ిྗɺड৴ײ౓ɺΞϯςφؒΞΠιϨʔγϣϯɺS/NൺɺμΠφϛοΫϨϯδɺޙ ํน൓ࣹ

Fig.14 Microwave level chart: transmit power, receiving sensitivity, antenna isolation, S/N ratio, dynamic-range, wall back-scattering.

Ίɺޙน͸௿൓ࣹͰ͋Δඞཁ͕͋Ζ͏ɻ ʢ5ʣϓϩʔϒΞϯςφͷҐஔਫ਼౓ɺαϯϓϦϯάɺϐο ν:ྫ͑͹ɺ൓ࣹڸΞϯςφͷද໘ਫ਼౓͸λ/10 rmsҎ಺ Ͱ͋Δ͜ͱ͕๬·͍͠ઃܭ৚݅ͱͳ͍ͬͯΔɻ͜ͷڐ༰ ޡࠩʹΑΔΞϯςφརಘͷ௿Լ͸໿ 0.1 dBͰ͋Δɻಉ༷ ʹɺNFFFTܭଌͰͷϓϩʔϒͷҐஔܾΊਫ਼౓͸ํҐ֯ͱ ਨ௚ํ޲ͷ྆ํ޲Ͱಉ͡஋λ/10Ҏ಺ʹอͭ͜ͱ͕ਪ঑ ͞ΕΔɻҰํɺαϯϓϦϯάఆཧʹै͍ɺ͢΂ͯͷ૸ࠪ αϯϓϦϯάִؒ͸λ/2Ҏ಺ʹอͭඞཁ͕͋Δɻ

ਤ15 GTDʹΑΔಋମετϦοϓʹΑΔཧ࿦஋:෯

22.5 cm (4.13λ)ɺ্:ۙ๣ք (52 cm=9.53λ)ɺԼ:ԕ ํք

Fig.15 GTD calculation of conducting strip, width 22.5 cm (4.13λ),upper: near-field pattern

at 52 cm (9.53λ),lower: far-field pattern.

(6)λʔήοτͰͷଟॏ൓ࣹ:ߤۭػͷਨ௚ඌཌྷͳͲɺ λʔήοτܗঢ়͕ෳࡶͰ͋Δͱ͖ɺλʔήοτࣗମͰଟ ॏͷ൓ࣹ೾͕ൃੜ͢Δɻޫઢ௥੻ (ray tracing)ͳͲ ͷํ๏Ͱ͜ͷ൓ࣹ෦ҐΛ֬ೝ͠ɺͦͷେ͖͞ʹԠͯ͡ϓ ϩʔϏϯάڑ཭ΛͰ͖Δ͚ͩ཭ͯ͠ܭଌ͢Δ͜ͱΛਪ঑ ͢Δɻ ʢ7ʣؒҾ͖(thinning)ܭଌ_{: z−}ํ޲ͷి࣓ք෼෍ ͷύλʔϯΛ༧ଌͯ͠ɺ୺ํ޲ʹ޲͔ͬͯαϯϓϧ఺Λ ݮΒ͢͜ͱ͕Ͱ͖Δɻ͜ͷؒҾ͖๏͸ඇৗʹޮՌతͰ͋ Γɺଌఆͱܭࢉͷ࣌ؒίετ࡟ݮʹد༩͢Δɻ ʢ8ʣߴ଎ϑʔϦΤม׵(FFT):ಘΒΕͨܭଌσʔλʹ ͸ɺॴ๬ͷࢄཚ೾ͷଞʹɺ࣮ଌ؀ڥʹ͓͚Δ͋ΒΏΔෆ ཁ೾ؚ͕༗͞Ε͍ͯΔɻ௨ৗɺ͜ͷෆཁ೾Λ཈ѹ͢Δͨ ΊʹɺσʔλΛ࣌ؒ࣠ʹม׵͠ɺ࣌ؒϑΟϧλɺͭ·Γ FFTख๏ʹΑΓআڈ͍ͯ͠ΔɻKOSIPͰ͸ɺ͜ͷϙετ ॲཧͷϧʔνϯΛ༻ҙ͍ͯ͠Δɻͳ͓ɺޙड़ͷΑ͏ʹຊ ਤ16 ਤ15ͷۙ๣քσʔλʹΑΔNFFTॲཧ:Ϩʔμը ૾(্)ͱԕํύλʔϯ(Լ)

Fig.16 NFFFT processing image and far-field pattern by inputting GTD near-field data in the

upper of Fig.15. ࿦Ͱ͸ɺը૾ʹΑΔۭؒ࣠Ͱ΋FFTʹΑΔ࣌ؒ࣠ॲཧͱ ಉ༷ʹআڈͰ͖Δ͜ͱΛ࣮ূ͓ͯ͠ΓɺࠓޙKOSIPʹ౥ ࡌ༧ఆͰ͋Δɻ 5. ಋମฏ൘ʹΑΔKOSIP-NFFFTͷଥ౰ੑݕূ ຊઅͰ͸ઌͣɺ୯७ͳGTDϞσϧΛ༻͍ͯಋମฏ൘ͷ NFFTܭଌͱཧ࿦஋ม׵ʹ͍ͭͯߟ࡯͢Δɻਤ15͸ϐʔ Ϋ஋Ͱਖ਼نԽ͞ΕͨࢄཚքύλʔϯͰ͋ΓɺಋମετϦο ϓͷ෯22.5 cm(4.13λ)ͷزԿޫֶతճંཧ࿦(GTD)ʹ ΑΔܭࢉ݁ՌͰ͋Δɻಉਤͷ্͸ρ0= 52 cm(9.53λ)ͷ ۙ๣քύλʔϯͰ͋ΓɺԼਤ͸ԕํྖҬͰͷύλʔϯͰ ͋Δɻਤ16͸ਤ15ͷGTDۙ๣քσʔλΛKOSIPʹೖྗ ͨ͠ͱ͖ͷNFFFTॲཧը૾(্ଆ)ͱԕํύλʔϯ(Լ ଆ)Ͱ͋Δɻ ্هཧ࿦త݁Ռ͸ɺNFFFTଌఆม׵ʹΑͬͯ༰қʹ֬ೝ Ͱ͖Δɻਤ17ʹଌఆதͷ༷ࢠͱଌఆύϥϝʔλΛࣔ͢ɻ ਤ18͸ۙ๣ք(্)ͱʣNFFFTม׵͞Εͨԕํύλʔϯ

ਤ15 GTDʹΑΔಋମετϦοϓʹΑΔཧ࿦஋:෯

22.5 cm (4.13λ)ɺ্:ۙ๣ք (52 cm=9.53λ)ɺԼ:ԕ ํք

Fig.15 GTD calculation of conducting strip, width 22.5 cm (4.13λ),upper: near-field pattern

at 52 cm (9.53λ),lower: far-field pattern.

(6)λʔήοτͰͷଟॏ൓ࣹ:ߤۭػͷਨ௚ඌཌྷͳͲɺ λʔήοτܗঢ়͕ෳࡶͰ͋Δͱ͖ɺλʔήοτࣗମͰଟ ॏͷ൓ࣹ೾͕ൃੜ͢Δɻޫઢ௥੻ (ray tracing)ͳͲ ͷํ๏Ͱ͜ͷ൓ࣹ෦ҐΛ֬ೝ͠ɺͦͷେ͖͞ʹԠͯ͡ϓ ϩʔϏϯάڑ཭ΛͰ͖Δ͚ͩ཭ͯ͠ܭଌ͢Δ͜ͱΛਪ঑ ͢Δɻ ʢ7ʣؒҾ͖(thinning)ܭଌ_{: z−}ํ޲ͷి࣓ք෼෍ ͷύλʔϯΛ༧ଌͯ͠ɺ୺ํ޲ʹ޲͔ͬͯαϯϓϧ఺Λ ݮΒ͢͜ͱ͕Ͱ͖Δɻ͜ͷؒҾ͖๏͸ඇৗʹޮՌతͰ͋ Γɺଌఆͱܭࢉͷ࣌ؒίετ࡟ݮʹد༩͢Δɻ ʢ8ʣߴ଎ϑʔϦΤม׵(FFT):ಘΒΕͨܭଌσʔλʹ ͸ɺॴ๬ͷࢄཚ೾ͷଞʹɺ࣮ଌ؀ڥʹ͓͚Δ͋ΒΏΔෆ ཁ೾ؚ͕༗͞Ε͍ͯΔɻ௨ৗɺ͜ͷෆཁ೾Λ཈ѹ͢Δͨ ΊʹɺσʔλΛ࣌ؒ࣠ʹม׵͠ɺ࣌ؒϑΟϧλɺͭ·Γ FFTख๏ʹΑΓআڈ͍ͯ͠ΔɻKOSIPͰ͸ɺ͜ͷϙετ ॲཧͷϧʔνϯΛ༻ҙ͍ͯ͠Δɻͳ͓ɺޙड़ͷΑ͏ʹຊ ਤ16 ਤ15ͷۙ๣քσʔλʹΑΔNFFTॲཧ:Ϩʔμը ૾(্)ͱԕํύλʔϯ(Լ)

Fig.16 NFFFT processing image and far-field pattern by inputting GTD near-field data in the

upper of Fig.15. ࿦Ͱ͸ɺը૾ʹΑΔۭؒ࣠Ͱ΋FFTʹΑΔ࣌ؒ࣠ॲཧͱ ಉ༷ʹআڈͰ͖Δ͜ͱΛ࣮ূ͓ͯ͠ΓɺࠓޙKOSIPʹ౥ ࡌ༧ఆͰ͋Δɻ 5. ಋମฏ൘ʹΑΔKOSIP-NFFFTͷଥ౰ੑݕূ ຊઅͰ͸ઌͣɺ୯७ͳGTDϞσϧΛ༻͍ͯಋମฏ൘ͷ NFFTܭଌͱཧ࿦஋ม׵ʹ͍ͭͯߟ࡯͢Δɻਤ15͸ϐʔ Ϋ஋Ͱਖ਼نԽ͞ΕͨࢄཚքύλʔϯͰ͋ΓɺಋମετϦο ϓͷ෯22.5 cm(4.13λ)ͷزԿޫֶతճંཧ࿦(GTD)ʹ ΑΔܭࢉ݁ՌͰ͋Δɻಉਤͷ্͸ρ0= 52 cm(9.53λ)ͷ ۙ๣քύλʔϯͰ͋ΓɺԼਤ͸ԕํྖҬͰͷύλʔϯͰ ͋Δɻਤ16͸ਤ15ͷGTDۙ๣քσʔλΛKOSIPʹೖྗ ͨ͠ͱ͖ͷNFFFTॲཧը૾(্ଆ)ͱԕํύλʔϯ(Լ ଆ)Ͱ͋Δɻ ্هཧ࿦త݁Ռ͸ɺNFFFTଌఆม׵ʹΑͬͯ༰қʹ֬ೝ Ͱ͖Δɻਤ17ʹଌఆதͷ༷ࢠͱଌఆύϥϝʔλΛࣔ͢ɻ ਤ18͸ۙ๣ք(্)ͱʣNFFFTม׵͞Εͨԕํύλʔϯ ਤ17 ಋମετϦοϓͷۙ๣քܭଌ

Fig.17 Near-field measurement for the conducting strip, width 22.5 cm (4.13λ) at 52 cm (9.53λ).

ਤ18 ۙ๣քܭଌσʔλ(্)Λ༻͍ͨԕํύλʔ ϯ(Լ)

Fig.18 NFFFT processing far-field pattern (lower) by inputting measured near-field data

(upper). (Լ) Ͱ͋Δɻͭ·ΓɺԕํRCSύλʔϯʹ͸ɺಉ͡ଌ ఆ͓Αͼܭࢉύϥϝʔλͷ3छྨͷύλʔϯ͕ൺֱͰ͖ Δ͜ͱʹͳΔɻ͜ΕΛ෼͔Γқ͘ݟΔͨΊɺ௚ަ࠲ඪͰ ਤ19ʹࣔ͢ɻฏ൘΁ͷೖࣹྖҬΛআ͍ͯɺ͜ΕΒͷ3ݸ ͷύλʔϯ͸ڻ͘΄ͲҰக͍ͯ͠Δ͜ͱ͕෼͔ΔɻෆҰ கͷཧ༝ͱͯ͠͸ɺೋͭ΄Ͳߟ͑ΒΕΔɻ·ͣɺଌఆ͸ ࡾ࣍ݩ؀ڥͰߦΘΕΔ͕ɺܭࢉ͸ઢݯʹΑΔೋ࣍ݩͰ͋ Δ͜ͱɺୈೋʹɺۚଐฏ൘ͷ௕͕͞༗ݶͰ͋ΔͨΊɺԁप ૸ࠪͰܭଌ͍ͯ͠Δ͜ͱ͕ڍ͛ΒΕΔɻԿΕʹͤΑɺϝ Πϯϩʔϒͱ͜Εʹ͍ۙαΠυϩʔϒྖҬͰ΄΅׬શͳ ҰகΛ͍ࣔͯ͠Δɻ͜ͷݕূ͔Βɺຊ࿦ͰఏҊ͍ͯ͠Δ NFFFTॲཧ͕༗ޮͰ͋Δͱ݁࿦෇͚Δ͜ͱ͕Ͱ͖Δɻ ͜͜·Ͱݟ͖ͯͨΑ͏ʹɺஶऀ౳͕ఏҊ͢ΔNFFFTͰ ͸ɺয఺Խิਖ਼ؔ਺ʹΑΔਖ਼֬ͳۙڑ཭ ISAR ը૾͕ࢉ ग़ՄೳͱͳΓɺ͜ΕΑΓখܕͷి೾҉ࣨ಺Ͱͷܭଌ͕Ͱ ͖ΔΑ͏ʹͳΔɻࡾ࣍ݩԁ౵૸ࠪͰͷNFFFTཧ࿦Λ൓ө ͨ͠RCS ૯߹ධՁγεςϜKOSIPΛ௨͠ɺલड़ͷΑ͏ ʹཧ࿦ͷଥ౰ੑΛ֬ೝͨ͠ɻϦϞʔτηϯγϯάɺಁա Ϩʔμ౳ͷը૾΋ଘࡏ͢Δ͕ɺ͜ΕΒͷධՁ΋Մೳͱߟ ͍͑ͯΔɻKOSIPʹ͸ɺϒϩʔϒΞϯςφͷϏʔϜิਖ਼ ؔ਺ɺ࣌ؒ࣠ ήʔςΟϯάॲཧϧʔνϯɺಋମٿɺฏ൘ ϞσϧʹΑΔۙ๣քͱԕํքͷཧ࿦ܭࢉϧʔνϯ಺แ͠ ͓ͯΓɺࠓޙ΋Ϟσϧͷ֦ுΛ༧ఆ͍ͯ͠Δɻ͞ΒʹɺΞ ϯςφ์ࣹքͷNFFFTύλʔϯܭଌɺޙड़ͷۭؒ࣠ը૾ Ҭ੍ݶॲཧͷରԠ΋ՄೳͰ͋Δɻಛʹޙऀ͸λʔήοτ ͷը૾ۙ๣Ͱͷෆཁ෺൓ࣹɺૹड৴ΞϯςφؒͷճΓࠐ