Written by Dr. David Kirkby, G8WRB. email drkirkby@kirkbymicrowave.co.uk
The programme input allows one to specify the dimensions and location of all the antenna elements interactively. You would use this when you have a design you wish to evaluate.
The manual page input.1
describes all the options of input. The manual page input.5
describes the file format for input. However, it is better to read
this page before looking at the man pages.
In the following example, we will create a 2 element antenna for 14.2 MHz. The data will now be written to the file name 'example2'
parrot /export/home/drkirkby/yagiuda-1.18/src % input
Yagi-Uda antenna analysis programs, version 1.18
Written by Dr. David Kirkby Ph.D. (G8WRB, email:drkirkby@kirkbymicrowave.co.uk)
This program asks for length, diameter and position of antenna elements
then
writes them to a file you specify. Data is written in m (metres)
Enter any notes on this design (up to 400 characters): 2 ele beam
Enter a filename to write data to example2
Enter the centre frequency in MHz 14.1
Enter the minimum frequency in MHz 13.8
Enter the maximum frequency in MHz 14.6
Enter the frequency steps in MHz 0.05
Data can be entered in imperial (inches) metric (mm) or wavelengths
(lambda)
Please enter i (for imperial), m (for metric) or w (for wavelengths).
w
Enter the number of elements for the antenna 2
Enter the angular step size in degrees for the gain to be plotted
5
Are all the elements of the same diameter ? y
Enter the diameter of the elements (in lambda) 0.00526
Enter location of the driven element in lambda (wrt. reflector at
x=0) 0.1
Enter length of the driven element (in lambda) 0.48167
Enter length of the reflector (in lambda) .49
Now we will inspect the file example 2. Note that the dimensions of the elements are written in metres, not wavelengths. This always happens, no matter what units you use to input data. We will see that the programme input just writes the data to the text file in the same format as the programme first.
parrot /export/home/drkirkby/yagiuda-1.18/src % cat example2
NOTES 2 ele beam
FREQUENCY 14.100000
MIN_FREQUENCY 13.800000
MAX_FREQUENCY 14.600000
STEP_FREQUENCY 0.050000
ELEMENTS 2
DRIVEN 1
PARASITIC 1
ANGULAR_STEP 5.000000
#DATA_DRIVEN x
y length diameter
voltage(r) voltage(i)
DATA_DRIVEN 2.12766 0.00000
10.24830 0.11191 1.00000
0.00000
#DATA_PARASITIC x
y length diameter
DATA_PARASITIC
0.00000 0.00000 10.42553
0.11191 reflector
We will now calculate the elements currents using yagi.
To avoid the programming printing to stdout things like
yagi completed 0.0% f=13800000.000000 MHz
yagi completed 6.2% f=13850000.000000 MHz
etc., we will use the -s flag to yagi and suppress the
output.
parrot /export/home/drkirkby/yagiuda-1.18/src % yagi -s example2
The we use output to calculate the performance, but again
use the -s option to suppress diagnostic output.
parrot /export/home/drkirkby/yagiuda-1.18/src % output -s example2
Numerical Recipes run-time error...
Root must be bracketed in ZBRENT - try the -e or -h options to
output
...now exiting to system...
This has shown a problem. One of the numerical routines has failed. This is because the programme tries to find the 3 dB E and H plane beamwidths, but has failed to do this.
We will first try to suppress the calculation of the E field 3 dB beamwidth to see if that stops the problem.
parrot /export/home/drkirkby/yagiuda-1.18/src % output -s -e example2
Numerical Recipes run-time error...
Root must be bracketed in ZBRENT - try the -e or -h options to
output
...now exiting to system...
That did not work, so now try the -h option to suppress calculation of the 3 dB H-plane beamwidth.
parrot /export/home/drkirkby/yagiuda-1.18/src % output -s -h example2
That worked fine, so we can inspect the performance of the antenna.
parrot /export/home/drkirkby/yagiuda-1.18 % cat example2.dat
# Driven=1 parasitic=1 total-elements=2 design=14.100MHz
# Checked from 13.800MHz to 14.600MHz.
f(MHz) E(deg) H(deg) R jX
VSWR Gain(dBi) FB(dB)
SideLobes(dB)
13.800 63.3 0.0 9.51
0.95 5.262 6.840
2.836 0.000
13.850 63.9 0.0 10.11 5.20
4.999 7.006
3.768 0.000
13.900 64.4 0.0 10.83 9.39
4.786 7.105
4.667 0.000
13.950 64.9 0.0 11.65 13.51
4.621 7.152
5.531 0.000
14.000 65.3 0.0 12.56 17.57
4.502 7.161
6.355 0.000
14.050 65.6 0.0 13.54 21.54
4.424 7.140
7.135 0.000
14.100 65.9 0.0 14.58 25.44
4.380 7.099
7.863 0.000
14.150 66.3 0.0 15.67 29.26
4.367 7.043
8.532 0.000
14.200 66.5 0.0 16.81 33.01
4.379 6.978
9.132 0.000
14.250 66.8 0.0 17.98 36.68
4.411 6.908
9.658 0.000
14.300 67.0 0.0 19.17 40.29
4.461 6.833 10.103
0.000
14.350 67.3 0.0 20.38 43.83
4.524 6.757 10.463
0.000
14.400 67.5 0.0 21.61 47.31
4.600 6.681 10.740
0.000
14.450 67.6 0.0 22.84 50.73
4.686 6.606 10.935
0.000
14.500 67.8 0.0 24.08 54.10
4.780 6.532 11.056
0.000
14.550 68.0 0.0 25.32 57.43
4.881 6.460 11.112
0.000
14.600 68.1 0.0 26.56 60.71
4.989 6.390 11.113
0.000
Note the H-field beamwidth is not shown, although it is
for the E-field, as we needed to suppress the H-field data to stop the
numerical error.
At the design frequency (14.1 MHz) our antenna has a gain of 7.024 dBi and an input Z of 11.06 + j18.45 Ohms.
Note the column marked SideLobes(dB) shows only zeros. The calculation of the most significant sidelobe, wherever it is, can be found, if the -c option to output is added. This can take quite a bit longer, so is not selected by default.
parrot /export/home/drkirkby/yagiuda-1.18 % output -s -h -c example2
parrot /export/home/drkirkby/yagiuda-1.18 % cat example2.dat
# Driven=1 parasitic=1 total-elements=2 design=14.100MHz
# Checked from 13.800MHz to 14.600MHz.
f(MHz) E(deg) H(deg) R jX
VSWR Gain(dBi) FB(dB)
SideLobes(dB)
13.800 63.3 0.0 9.51
0.95 5.262 6.840
2.836 2.836
13.850 63.9 0.0 10.11 5.20
4.999 7.006
3.768 3.768
13.900 64.4 0.0 10.83 9.39
4.786 7.105
4.667 4.667
13.950 64.9 0.0 11.65 13.51
4.621 7.152
5.531 5.531
14.000 65.3 0.0 12.56 17.57
4.502 7.161
6.355 6.355
14.050 65.6 0.0 13.54 21.54
4.424 7.140
7.135 7.135
14.100 65.9 0.0 14.58 25.44
4.380 7.099
7.863 7.863
14.150 66.3 0.0 15.67 29.26
4.367 7.043
8.532 8.532
14.200 66.5 0.0 16.81 33.01
4.379 6.978
9.132 9.132
14.250 66.8 0.0 17.98 36.68
4.411 6.908
9.658 9.658
14.300 67.0 0.0 19.17 40.29
4.461 6.833 10.103
10.103
14.350 67.3 0.0 20.38 43.83
4.524 6.757 10.463
10.463
14.400 67.5 0.0 21.61 47.31
4.600 6.681 10.740
10.740
14.450 67.6 0.0 22.84 50.73
4.686 6.606 10.935
10.935
14.500 67.8 0.0 24.08 54.10
4.780 6.532 11.056
11.056
14.550 68.0 0.0 25.32 57.43
4.881 6.460 11.112
11.112
14.600 68.1 0.0 26.56 60.71
4.989 6.390 11.113
11.113
parrot /export/home/drkirkby/yagiuda-1.18 %
The rather poor 2-element can be optimised like any other design with optimise.