Version 4 SHEET 1 1536 920 WIRE 176 32 160 32 WIRE 224 32 176 32 WIRE 320 32 224 32 WIRE 1024 112 816 112 WIRE 160 128 160 32 WIRE 224 128 224 32 WIRE 816 144 816 112 WIRE 320 176 320 112 WIRE 368 176 320 176 WIRE 464 176 368 176 WIRE 608 176 528 176 WIRE 1024 176 1024 112 WIRE 608 208 608 176 WIRE 320 224 320 176 WIRE 816 256 816 224 WIRE 816 272 816 256 WIRE 608 288 608 272 WIRE 160 304 160 192 WIRE 224 304 224 192 WIRE 224 304 160 304 WIRE 320 304 224 304 WIRE 608 320 608 288 WIRE 224 352 224 304 WIRE 816 368 816 352 WIRE 1024 368 1024 256 WIRE 1024 368 816 368 WIRE 1024 416 1024 368 WIRE 608 432 608 400 WIRE 608 480 608 432 WIRE 608 576 608 560 FLAG 224 352 0 FLAG 176 32 mem FLAG 368 176 x FLAG 1024 416 0 FLAG 608 576 0 FLAG 816 256 e FLAG 608 432 a FLAG 608 288 b FLAG 608 176 c FLAG 1024 112 f SYMBOL cap 208 128 R0 SYMATTR InstName C1 SYMATTR Value 1nF SYMBOL cap 144 128 R0 WINDOW 0 -129 12 Left 2 WINDOW 3 -79 52 Left 2 SYMATTR InstName Cmembrane SYMATTR Value 10nF SYMBOL ind2 304 16 R0 SYMATTR InstName L1 SYMATTR Value 0.01mH SYMATTR Type ind SYMBOL ind2 304 208 R0 SYMATTR InstName L2 SYMATTR Value 0.01mH SYMATTR Type ind SYMBOL voltage 1024 160 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName Vant SYMATTR Value SINE(0 100 0.3G) SYMBOL cap 528 160 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName Cplunger SYMATTR Value 10nF SYMBOL ind2 592 464 R0 WINDOW 0 -54 20 Left 2 WINDOW 3 -57 67 Left 2 SYMATTR InstName Lant SYMATTR Value 40mH SYMATTR Type ind SYMBOL ind2 832 128 M0 WINDOW 0 -77 34 Left 2 WINDOW 3 -59 65 Left 2 SYMATTR InstName Levas SYMATTR Value 10H SYMATTR Type ind SYMBOL res 832 368 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R1 SYMATTR Value 1.8K SYMBOL res 592 304 R0 SYMATTR InstName Rant SYMATTR Value 50 SYMBOL cap 592 208 R0 SYMATTR InstName Cant SYMATTR Value 100nF TEXT 24 -56 Left 2 ;Inspired by 'The Thing Great Seal Bug', Crypto Museum. TEXT 456 -24 Left 2 !.tran 0 15u 5u TEXT -928 360 Left 2 ;Try Cmembrane 10nF v.s. 40nF.\n10nF --> natural freq. (w_d/2pi) ~ 340KHz\n40nF --> natural freq. (w_d/2pi) ~ 176KHz. TEXT -944 -16 Left 2 ;Notice that this does not have R. TEXT -936 24 Left 2 ;It is arranged to achieve under-damped with a1 ~ 0, so that the oscillation does not decay, TEXT -928 72 Left 2 ;KVL: -Vc + Vl1 + Vl2 = 0\nL properties: -Vc + L1 di/dt + L2 di/dt = 0\nC properties: -i = (Cmem + C1) dVc/dt # parallel C: Ceff = C1 + C2\n(3) plugs into (2): -Vc - (L1 + L2)(Cmem + C1) d2 Vc/ dt2.\nRe-arrange: LC d2 Vc/dt2 + 0 d Vc/dt + Vc = 0, where L = L1 + L2, C = Cmem + C1\nThat is, a2 = LC, a1 = 0, a0 = 1, f(t) = 0. TEXT -928 624 Left 2 ;(Model A) Only natural response. No antenna modeling.\n(Model B) Classic antenna modeling: RLC + V source, R ~50-75, L and C gets Q factor ~12.\nE.g., L = 40mH, C = 100nF, R = 50.\n(Model C) Simple antenna modeling: V source.\n[.tran 100ms] --> see the difference.\n* To see FFT, right-click > view > FFT.\n(Model D) Inductance coupling modeling. TEXT 456 8 Left 2 !.ic V(mem) = 0.02m TEXT 720 440 Left 2 !K Lant Levas 0.01 TEXT -832 264 Left 2 ;Underdamped, natural frequency, w_d = sqrt(4*a0*a2 - a1^2)/(2*a2).\nTherefore, w_d = 1/sqrt(L*C). TEXT -928 464 Left 2 ;It should be noted that '.ic V(mem) = 0.02m' is crucial in this simulation, \nsince i.c. = 0 results in no natural response (coeff = 0).\n \nIn practice, Cmembrame and C1 have to be at least partially charged. (i.c. is not 0). LINE Normal 640 528 640 528 2 LINE Normal 784 192 640 528 2