DRAFT Recommended Practice for Measurements and ...

More documents

Recommendations

Info

1/29/98 102 C95.3-1991 Revision — 2 nd Draft 10/98 Draft V = RMS voltage on each line with respect to the neutral plane midway between the wires (V) Z 0 = Characteristic impedance of the transmission line (Ω) = 120 cosh -1 (d/r) d = Distance from the field point P (midpoint of line) to the center of each wire (m) r = Radius of each wire (m) Fig A3 Parallel Wire Transmission Line for Generating E- and H-Fields Copyright © 1998 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft, subject to change.
1/29/98 103 C95.3-1991 Revision — 2 nd Draft 10/98 Draft Fig A4 Long-wire Antenna Chamber A5. Long-wire Antenna Chamber A standard screen room can be converted into a chamber with calculable E- and H- fields. This provides a large volume with a moderately uniform field distribution for the exposure of objects or for antenna calibrations at frequencies up to about 30 MHz. As shown in Fig A4, a single wire is stretched horizontally between two insulators that are attached at opposite ends of the screen room. For a typical room with a height of 8 ft, the wire height is usually about 6 ft above the floor. This TEM transmission line is usually fed via a coaxial transmission line at one end of the room, using a shunt resistor R 1 to help terminate the coaxial line in its characteristic impedance. Resistor R 2 is used to terminate the single wire line in its characteristic impedance (usually 300 - 600 ohms). Theoretical investigations of the fields in a screen room, when energized by a single-wire transmission line, indicate that the field uniformity is quite poor. The distribution of the E and H fields below the line depends on optimization of the line-terminating impedance. Equations to determine the values of E and H, and the approximate values of R 1 and R 2 are given in the literature [A1, A2, A3, A4]. In the derivation of these equations, it is assumed that a pure resistance is an adequate termination for the wire transmission line. If the line height is greater than 2/3 the room height, the presence of the side walls and floor of the screen room is generally ignored when calculating the characteristic impedance of the line. The field strength at point P, near the center of the screen room, is given approximately by E ≈ 60V ⎛ 1 1 1 1 1 ⎜ − − + + Z Z ⎝ d d + 2a d − 2b d − 2a − 2b d + 2a + 2b ( 0 + g ) and 1 1 1 − − + ⎞ ⎟ d − 2a + 4b d + 4a + 2b d − 4a − 4b⎠ H ≈ E/377 (Eq A3) where: E = Electric field strength at point P midway between the ends of the screen room (V/m) H = Magnetic field strength at the same point (A/m) V = Voltage on the single wire transmission line (V) Z 0 = Characteristic impedance of the line ([W]) ≈ 60 ln (2a/r) Z g = Impedance of the generator (Ω) r = Radius of the wire (m) a = Distance from the wire to the ceiling (m) b = Distance from the wire to the floor (m) Copyright © 1998 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft, subject to change.
Page 1 and 2:
1/29/98 C95.3-1991 Revision—3rd D
Page 3 and 4:
1/29/98 3 C95.3-1991 Revision — 2
Page 5 and 6:
1/29/98 5 C95.3-1991 Revision — 2
Page 7 and 8:
1/29/98 7 C95.3-1991 Revision — 2
Page 9 and 10:
1/29/98 9 C95.3-1991 Revision — 2
Page 11 and 12:
1/29/98 11 C95.3-1991 Revision —
Page 13 and 14:
1/29/98 13 C95.3-1991 Revision —
Page 15 and 16:
1/29/98 15 C95.3-1991 Revision —
Page 17 and 18:
1/29/98 17 C95.3-1991 Revision —
Page 19 and 20:
1/29/98 19 C95.3-1991 Revision —
Page 21 and 22:
1/29/98 21 C95.3-1991 Revision —
Page 23 and 24:
1/29/98 23 C95.3-1991 Revision —
Page 25 and 26:
1/29/98 25 C95.3-1991 Revision —
Page 27 and 28:
1/29/98 27 C95.3-1991 Revision —
Page 29 and 30:
1/29/98 29 C95.3-1991 Revision —
Page 31 and 32:
1/29/98 31 C95.3-1991 Revision —
Page 33 and 34:
1/29/98 33 C95.3-1991 Revision —
Page 35 and 36:
1/29/98 35 C95.3-1991 Revision —
Page 37 and 38:
1/29/98 37 C95.3-1991 Revision —
Page 39 and 40:
1/29/98 39 C95.3-1991 Revision —
Page 41 and 42:
1/29/98 41 C95.3-1991 Revision —
Page 43 and 44:
1/29/98 43 C95.3-1991 Revision —
Page 45 and 46:
1/29/98 45 C95.3-1991 Revision —
Page 47 and 48:
1/29/98 47 C95.3-1991 Revision —
Page 49 and 50:
1/29/98 49 C95.3-1991 Revision —
Page 51 and 52: 1/29/98 51 C95.3-1991 Revision —
Page 101: 1/29/98 101 C95.3-1991 Revision —
show all

DRAFT Recommended Practice for Measurements and ...

Create successful ePaper yourself

Delete template?

Save as template?