pi = ATN(1) * 4
10 CLS : PRINT "ALL DIMENSIONS IN mm."
20 '
30 '
40 DEF FNrj (ta, b, c, d) = (b * c - ta * d) / (c * c + d * d)
50 '
60 '
70 DIM g(200), c(200), rk(200), ak(200), fr(40), aloss(40)
80 DIM a(200), b(200)
90 '
100 INPUT "# of elements"; n
105 INPUT "# p-p ripple in passband"; rip
110 '
120 INPUT "filter center freq (GHz)"; fzgc
121 INPUT "bandwidth (MHz)"; bwmc
122 INPUT "load impedance"; r
130 '
140 INPUT "ground plane spacing"; h: h = h / 25.4
141 INPUT "rod diameter"; d: d = d / 25.4
150 INPUT "distance to center of 1st and last rod"; e: e = e / 25.4
160 '
170 '
180 INPUT "#of freq rej displayed points (max 37)"; nfr
181 INPUT "step size"; stp: PRINT
190 FOR ip = -nfr / 2 TO nfr / 2
200 co = co + 1
210 fr(co) = fzgc + (stp * .001 * ip)
220 NEXT ip
230 idat = 1
240 GOTO 250
250 f1 = fzgc - .0005 * bwmc
260 f2 = fzgc + .0005 * bwmc
270 IF rip > 0 THEN 330
280 bw3gc = f2 - f1
290 bwrgc = 0
300 bw3 = 1
310 GOSUB 1960
320 GOTO 390
330 b = 1 / SQR(10 ^ (.1 * rip) - 1)
340 ca = LOG(b + SQR(b * b - 1)) / n
350 bw3 = (EXP(ca) + EXP(-ca)) / 2
360 GOSUB 1740
370 bwrgc = f2 - f1
380 bw3gc = bwrgc * bw3
390 '
400 w = 2 * (f2 - f1) / (f2 + f1)
410 qf = fzgc / bw3gc
420 nfm = n - 1
430 qwvl = 11.8028 / 4 / fzgc
440 FOR k = 1 TO nfm
450 ak(k) = 1 / (bw3 * SQR(g(k) * g(k + 1)))
460 rk(k) = ak(k) / qf
470 NEXT k
480 ako = g(1) * bw3
490 ak(n) = ako
500 ak(n + 1) = 0
510 qs = g(1) * bw3 * qf
520 canh = (EXP(2 * pi * e / h) - 1) / (EXP(2 * pi * e / h) + 1)
530 zm = 59.9585 * LOG(4 * h / pi / d)
540 ze = 59.9585 * LOG(canh * h * 4 / pi / d)
550 rkm = rk(1) * SQR(zm / ze)
560 z = pi * d / 2 / h
570 coth = (EXP(z) + 1) / (EXP(z) - 1)
580 y = pi * rkm / 4
590 t = coth ^ y
600 c(1) = h / pi * LOG((t + 1) / (t - 1))
610 mfl = n - 2
620 '
630 ON (2 + SGN(n) * 1) GOTO 690, 690, 640
640 FOR k = 2 TO mfl
650 y = pi * rk(k) / 4
660 t = coth ^ y
670 c(k) = h / pi * LOG((t + 1) / (t - 1))
680 NEXT k
690 c(n - 1) = c(1)
700 x = SQR(pi * r / 4 / ze / qs)
710 aq = 2 * qwvl * ATN(x / SQR(1 - x * x)) / pi
720 qu = 2200 * h * SQR(fzgc)
730 sumg = 0
740 FOR j1 = 1 TO n
750 sumg = sumg + g(j1)
760 NEXT j1
770 bloss = 4.34 * fzgc * sumg / qu / (f2 - f1)
780 delay = sumg / 2 / pi / (f2 - f1)
790 IF rip > 0 THEN 820
800 PRINT "DESIGN DATA FOR "; n; " POLES INTERDIGITAL FILTER, BUTTERWORTH RESPONSE"
810 GOTO 830
820 PRINT "DESIGN DATA FOR"; n; "POLES INTERDIGITAL FILTER, BAND PASS RIPPLE"; rip; " dB": PRINT
830 PRINT "center frequency"; fzgc; "Ghz"
840 PRINT "cut off frequency "; FIX(f1 * 1000 + .5) / 1000; " and "; FIX(f2 * 1000 + .5) / 1000; "Ghz"
850 PRINT "ripple bandwidth"; bwrgc; "Ghz"
860 PRINT "3dB bandwidth"; bw3gc; "Ghz"
870 PRINT "fractionnal bandwidth"; w
880 PRINT "filter Q"; qf
890 PRINT "est. Qu"; qu
900 PRINT "loss based on this est. Qu"; bloss; "dB"
910 PRINT "delay at band center"; delay; "nS"
PRINT "print screen then press key": WHILE INKEY$ = "": WEND: CLS
920 FOR jk = 1 TO nfr
930 IF jk = 1 THEN PRINT "FREQUENCY REJECTION INFORMATION": PRINT TAB(65); "F"; TAB(73); "Att": PRINT
940 nfn = ABS(2 * (fr(jk) - fzgc) / (w * fzgc))
950 IF rip > 0 THEN 980
960 aloss(jk) = 10 * LOG(1 + nfn ^ (2 * n)) / LOG(10)
970 GOTO 1020
980 IF nfn < 1 THEN nfn = 1
990 ang = n * LOG(nfn + SQR(nfn * nfn - 1))
1000 yak = .5 * (EXP(ang) + EXP(-ang))
1010 aloss(jk) = 10 * LOG(1 + (10 ^ (.1 * rip) - 1) * yak * yak) / LOG(10)
1020 IF aloss(jk) > 63 THEN aloss = 63 ELSE aloss = aloss(jk)
1030 fr = INT(fr(jk) * 10000) / 10000: alos = INT(aloss(jk))
1040 PRINT TAB(INT(aloss) + 1); "*"; TAB(65); fr; TAB(73); FIX(alos)
1050 NEXT jk
1060 wo = 2 * pi * fzgc * 1E+09
1070 f = d / h
1080 cf = (-.0000422# + .0857397# * f + .0067853# * f * f - 9.092165000000001D-02 * f ^ 3 + .169088 * f ^ 4) * pi * h * 2.54
1090 '
1100 ww = wo * 1E-12
1110 b2 = pi * aq / 2 / qwvl
1120 gg = 1 / r
1130 bb = -COS(b2) / ze / SIN(b2)
1140 el1 = .8 * qwvl
1150 ang = el1 * pi / 2 / qwvl
1160 b1 = ang - b2
1170 yl = -COS(ang) / zm / SIN(ang)
1180 cp = ww * (cf + .17655 * d * d / (qwvl - el1))
1190 y1 = cp + yl
1200 el2 = .87 * qwvl
1210 ang = el2 * pi / 2 / qwvl
1220 b4 = ang - b2
1230 yl = -COS(ang) / zm / SIN(ang)
1240 cd = ww * (cf + .17655 * d * d / (qwvl - el2))
1250 y2 = cd + yl
1260 el3 = .95 * qwvl
1270 ang = el3 * pi / 2 / qwvl
1280 b5 = ang - b2
1290 yl = -COS(ang) / zm / SIN(ang)
1300 cq = ww * (cf + .17655 * d * d / (qwvl - el3))
1310 y3 = cq + yl
1320 elem = y3 * y2 * el1 / ((y1 - y2) * (y1 - y3)) + y1 * y3 * el2 / ((y2 - y1) * (y2 - y3)) + y1 * y2 * el3 / ((y3 - y1) * (y3 - y2))
1330 tann = SIN(b1) / COS(b1)
1340 yl = FNrj(gg, bb + tann / ze, 1 - ze * bb * tann, ze * gg * tann)
1350 y1 = cp + yl
1360 tann = TAN(b4)
1370 yl = FNrj(gg, bb + tann / ze, 1 - ze * bb * tann, ze * gg * tann)
1380 y2 = cd + yl
1390 tann = TAN(b5)
1400 yl = FNrj(gg, bb + tann / ze, 1 - ze * bb * tann, ze * gg * tann)
1410 y3 = cq + yl
1420 eleq = y3 * y2 * el1 / ((y1 - y2) * (y1 - y3)) + y1 * y3 * el2 / ((y2 - y1) * (y2 - y3)) + y1 * y2 * el3 / ((y3 - y1) * (y3 - y2))
1430 '
PRINT "print screen then press key": WHILE INKEY$ = "": WEND: CLS
PRINT "MECHANICAL INFOS"
1440 PRINT "1/4 lambda="; qwvl * 25.4; "mm"
1450 PRINT "lenght of interior elts"; elem * 25.4; "mm"
1460 PRINT "lenght of end elts"; eleq * 25.4; "mm"
1470 PRINT "ground plane spacing"; h * 25.4; "mm"
1480 PRINT "rod diameter"; d * 25.4; "mm"
1490 PRINT "end plates"; e * 25.4; "mm from center of end rods"
1500 PRINT "tap external lines up"; aq * 25.4; "mm from shorted end"
1510 PRINT "line impedances: end rods:"; ze; ",other:"; zm; "Ohms"
1520 PRINT "dimensions:"
1530 PRINT TAB(1); "el N."; TAB(16); "end to C"; TAB(28); "C to C"; TAB(41); "g(k)"; TAB(55); "q/coup"
1540 dom = e
1550 goo = 1
1560 PRINT TAB(1); " 0"; TAB(41); goo; TAB(55); ako
1570 PRINT TAB(1); " 1"; TAB(16); FIX(e * 25.4 + .5); TAB(41); g(1); TAB(55); ak(1)
1580 FOR k = 1 TO nfm
1590 l = k + 1
1600 PRINT TAB(28); FIX(25.4 * c(k) + .5)
1610 dom = dom + c(k)
1620 PRINT TAB(1); l; TAB(16); FIX(dom * 25.4 + .5); TAB(41); g(l); TAB(55); ak(l)
1630 NEXT k
1640 lq = n + 1
1650 PRINT TAB(1); lq; TAB(41); g(lq)
1660 dom = dom + e
1670 PRINT TAB(16); FIX(dom * 25.4 + .5)
1680 IF idat = 1 THEN 2070
1690 '
1700 '
1710 '
1720 'DEF FNrj (ta, b, c, d) = (b * c - ta * d) / (c * c + d * d)
1730 END
1740 'sub cheb
1750 '
1760 c = 2 * rip / 17.37
1770 beta = LOG((EXP(c) + 1) / (EXP(c) - 1))
1780 gamma = .5 * (EXP(beta / (2 * n)) - EXP(-beta / (2 * n)))
1790 FOR k = 1 TO n
1800 a(k) = SIN(.5 * (2 * k - 1) * pi / n)
1810 b(k) = gamma ^ 2 + SIN(k * pi / n) ^ 2
1820 NEXT k
1830 g(1) = 2 * a(1) / gamma
1840 FOR k = 2 TO n
1850 g(k) = 4 * a(k - 1) * a(k) / (b(k - 1) * g(k - 1))
1860 NEXT k
1870 nn = n / 2
1880 nnn = (n + 1) / 2
1890 '
1900 ON (2 + SGN(nnn - nn) * 1) GOTO 1910, 1910, 1930
1910 g(n + 1) = ((EXP(beta / 2) + 1) / (EXP(beta / 2) - 1)) ^ 2
1920 RETURN
1930 g(n + 1) = 1
1940 RETURN
1950 END
1960 'sub for butt
1970 '
1980 '
1990 '
2000 '
2010 pov2 = 1.57079633#
2020 FOR k = 1 TO n
2030 g(k) = 2 * SIN(pov2 * (2 * k - 1) / n)
2040 NEXT k
2050 g(n + 1) = 1
2060 RETURN
2070 END