1.5波長ダイポール

By 平野拓一

<<Graphics`Colors`

(* モ - メント法の結果 *) ivec = {{0.00130625, 2.59957}, {0.00227347, 2.60505}, {0.00318249, 2.61032 ... }, {0.00402493, 2.61566}, {0.00318249, 2.61032}, {0.00227347, 2.60505}, {0.00130625, 2.59957}} ;

c = 3 * 10^8 ;

λ0 = 1. ;

k0 = (2 π)/λ0 ;

h = 1.5 * λ0/2 ;

nn = Length[ ivec ] ;

cur[n_, t_] := ivec[[n, 1]] * Cos[t + ivec[[n, 2]]] ;

grapdist = {Red, AbsoluteThickness[2], Line[Table[{100 * ivec[[i, 1]], ((i - 1)/(nn - 1)) * (2 * h) - h}, {i, 1, nn}]]} ;

Show[ Graphics[grapdist] ] ;

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(* t : 時間, n : 電荷数 *) charges[n_, t_] := Module[{r = (2 * h)/50}, {{Gray, Rectangle[{-r, - ... (2 * h/(n - 1)) * cur[IntegerPart[((i - 1)/(n - 1)) * (nn - 1)] + 1, t]}, r], {i, 1, n} ]}} ] ;

Table[Show[ Graphics[ {grapdist, charges[15, t]} ], AspectRatio -> Automatic ], {t, 0, 2 Pi - 0.001, 2 Pi/8}]

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{- Graphics -, - Graphics -, - Graphics -, - Graphics -, - Graphics -, - Graphics -, - Graphics -, - Graphics -}

微小ダイポールの放射電界

Overscript[r,^] . Overscript[x,^] = Sin[θ] Cos[\[CurlyPhi]] ;

Overscript[θ,^] . Overscript[x,^] = Cos[θ] Cos[\[CurlyPhi]] ;

Overscript[\[CurlyPhi],^] . Overscript[x,^] = Sin[\[CurlyPhi]] ;

Overscript[r,^] . Overscript[y,^] = Sin[θ] Sin[\[CurlyPhi]] ;

Overscript[θ,^] . Overscript[y,^] = Cos[θ] Sin[\[CurlyPhi]] ;

Overscript[\[CurlyPhi],^] . Overscript[y,^] = Cos[\[CurlyPhi]] ;

Overscript[r,^] . Overscript[z,^] = Cos[θ] ;

Overscript[θ,^] . Overscript[z,^] = Sin[θ] ;

Overscript[\[CurlyPhi],^] . Overscript[z,^] = 0 ;

er[i_, r_, θ_, t_] := 2 * Cos[θ] * (Cos[k0 * (c * t - r) + ivec[[i, 2]]]/(k0 * r)^2 + Sin[k0 * (c * t - r) + ivec[[i, 2]]]/(k0 * r)^3) ;

etheta[i_, r_, θ_, t_] := Sin[θ] * (Cos[k0 * (c t - r) + ivec[[i, 2]]]/(k0 * r)^2 - (1/(k0 * r) - 1/(k0 * r)^3) * Sin[k0 * (c t - r) + ivec[[i, 2]]]) ;

ex[i_, r_, θ_, \[CurlyPhi]_, t_] := Sin[θ] Cos[\[CurlyPhi]] er[i, r, θ, t] + Cos[θ] Cos[\[CurlyPhi]] etheta[i, r, θ, t] ;

ey[i_, r_, θ_, \[CurlyPhi]_, t_] := Sin[θ] Sin[\[CurlyPhi]] er[i, r, θ, t] + Cos[θ] Sin[\[CurlyPhi]] etheta[i, r, θ, t] ;

ez[i_, r_, θ_, \[CurlyPhi]_, t_] := Cos[θ] er[i, r, θ, t] + Sin[θ] etheta[i, r, θ, t] ;

energy[xo_, yo_, zo_, t_] := Module[{xs = 0, ys = 0, zs = 0, r, θ, \[CurlyPhi], exsum = 0, eysum = 0, ... ] ; ezsum += ivec[[i, 1]] * ez[i, r, θ, \[CurlyPhi], t] , {i, 1, nn} ] ; exsum^2 + eysum^2 + ezsum^2 ]

アニメーション

Table[DensityPlot[energy[0, x, y, t], {x, -2, 2}, {y, -2, 2}, ImageSize -> {200, 200}, Colo ... e, Rectangle[{-h/10., -h}, {h/10., h}]}], {t, 0, (π/(c k0)) - 0.001 * (π/(c k0)), (π/(c k0))/8}]

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{- DensityGraphics -, - DensityGraphics -, - DensityGraphics -, - DensityGraphics -, - DensityGraphics -, - DensityGraphics -, - DensityGraphics -, - DensityGraphics -}

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