Program listings for The Feedback Rhombic

http://home.comcast.net/~ross_anderson/FBRhombic.htm

 

CM  Figure 1  Rhombic with 3 wavelength legs and 850 ohm terminating resistor

CM  from "The Feedback Rhombic" from W1HBQ

CE  This program is written in 4nec2

SY x2 = 9093.1 'All dimensons are in inches

SY y2 = 4435   'Leg length is sqr(x2^2 + y2^2) = 10117 inches = 3 wavelengths

SY x3 = 2*x2

SY h = 3372.3  'Height is one wavelength

SY res = 425   'Termination resistance is 2*425 = 850 ohms

SY rad = .08   'Wire radius

SY freq = 3.5  'Frequency in MHz

GW      1          60        0          0          h          x2        y2        h          rad

GW      2          60        0          0          h          x2        -y2       h          rad

GW      3          60        x3        0          h          x2        y2        h          rad

GW      4          60        x3        0          h          x2        -y2       h          rad

GS       0          0          0.0254             ' All in in.

GE       0

LD       1          3          1          1          res        0

LD       1          4          1          1          res        0

EX       0          1          1          0          1          0

EX       0          2          1          0          -1         0

GN      2          0          0          0          13        0.005   'Average ground

FR       0          1          0          0          freq      0

EN

This model of the rhombic with a 3 wavelength leg length is from

"Long-Wire Antennas  Part 4: Rhombic Arrays and Beams",

by L. B. Cebik, W4RNL, available on the internet.

 

CM  Figure 2  Feedback Rhombic with 3 1/8 wavelength legs

CM  from "The Feedback Rhombic" from W1HBQ

CE  This program is written in 4nec2

SY x2 = 9590  'All dimensions are in inches.

SY x1 = 170   'x1, x2, x3, x4, y1, y2 set up the rhombic.

SY y2 = 4679  'The ends are blunted so that the transmission line can be inserted.

SY y1 = 83

SY x3 = 2*x2

SY x4 = x3 - x1

SY lambda = 3372.3 

SY h = lambda      'Height is one lambda (or one wavelength).

SY rad = .08

SY len = 19395     'Transmission line length in inches.    

SY ln = 0.0254*len 'This allows the transmission line length to be in inches.

SY freq = 3.5      'Frequency in MHz.

SY z0 = 1345 'This transmission line impedance gives antenna gain in the forward direction.

'SY z0 = 730 'This transmission line impedance gives antenna gain in the reverse direction.

GW      1          63        x1        y1        h          x2        y2        h          rad

GW      2          63        x1        -y1       h          x2        -y2       h          rad

GW      3          1          x1        -y1       h          x1        y1        h          rad

GW      4          63        x4        y1        h          x2        y2        h          rad

GW      5          63        x4        -y1       h          x2        -y2       h          rad

GW      6          1          x4        -y1       h          x4        y1        h          rad

GS       0          0          0.0254             ' All in in.

GE       0

EX       0          3          1          0          1          0

GN      2          0          0          0          13        0.005

TL        3          1          6          1          z0         ln          0          0          0          0

FR       0          1          0          0          freq      0

EN

The length of one side of the antenna (two times the leg length) is 10564 inches

which is about 6.25*lambda.

The length of the transmission line is 19395 inches, about 5.75*lambda.