Output data file formats
This manual page describes the output formats of the files created by the Yagi-Uda project's output program. The files are ASCII file, so can be analysed with any graph plotting program.
Below is a typical .dat file, for a 4ele 144-146MHz beam, optimised for a huge (and useless) FB.
# Driven=1 parasitic=3 total-elements=4 design=145.000MHz # Checked from 144.000MHz to 146.000MHz. f(MHz) E(deg) H(deg) R jX VSWR Gain(dBi) FB(dB) SideLobes(dB) 144.000 54.7 71.5 44.47 -2.35 1.136 9.386 21.944 16.650 144.500 54.0 70.1 41.34 -0.75 1.210 9.553 27.244 17.153 145.000 53.2 68.4 37.55 1.61 1.335 9.742 103.055 17.777 145.500 52.3 66.6 33.26 5.00 1.530 9.947 25.734 18.547 146.000 51.3 64.6 28.77 9.63 1.832 10.149 18.919 18.919
The f(MHz) column is the frequency (MHz) at which the data is evaluated at.
The E(deg) column is the approximate 3dB E-plane bandwidth calculated to the nearest 0.1 degree.
The H(deg) column is the approximate 3dB H-plane bandwidth calculated to the nearest 0.1 degree.
The (R) column is the input resistance in Ohms.
The (jX) column is the input reactance in Ohms.
The (VSWR) column is the input VSWR, usually refered to a 50 Ohm input, but this may be changed.
The Gain (dBi) column is the gain at theta=90 degrees, which is the forward direction of the beam. It is possible that a higher gain occurs at other than 90 degrees, but this is not taken into account. The antenna is seriously at fault if this occurs.
The FB(dB) column is the front to back ratio in dB.
The Sidelobes(dB) column is the minimum level in dB down from the peak gain of any sidelobe. This is not calculated unless the '-c' option is used, and then only on some optimisation techniques.
The following is a small section of the .gai file.
f(MHz) theta gain-E(dBi) G(E)-peak phi gain-H(dBi) G(H)-peak 144.0000 -90.0000 -12.5584 -21.9444 -180.0000 -12.5584 -21.9444 144.0000 -45.0000 -7.3507 -16.7367 -135.0000 -3.5971 -12.9830 144.0000 0.0000 -999.0000 -1008.3860 -90.0000 -0.9010 -10.2870 144.0000 45.0000 0.1848 -9.2012 -45.0000 4.0261 -5.3599 144.0000 90.0000 9.3860 0.0000 0.0000 9.3860 0.0000 144.0000 135.0000 0.1848 -9.2012 45.0000 4.0261 -5.3599 144.0000 180.0000 -999.0000 -1008.3860 90.0000 -0.9010 -10.2870 144.0000 225.0000 -7.3507 -16.7367 135.0000 -3.5971 -12.9830 144.0000 270.0000 -12.5584 -21.9444 180.0000 -12.5584 -21.9444
The f(MHz) column is the frequency in MHz.
The theta column is the angle theta, for which the next two columns refer.
The gain-E(dBi) is the gain at theta, relative to an isotropic radiator. This is the E-plane gain. Hence at the peak (theta), this gives the peak forward gain.
The G(E)-peak is the gain at theta, relative to the peak gain. Hence at the peak (theta=90 degrees), this is zero.
The phi column has nothing to do with the previous 3 columns. It is the angle for which the next two columns refer.
The gain-H(dBi) is the gain at phi, relative to an isotropic radiator. This is the H-plane gain. Hence at the peak (phi=0), this gives the peak forward gain.
The G(H)-peak is the gain at phi, relative to the peak gain. Hence at the peak (phi=0 degrees), this is zero.
The .up file list the improvements made by optimise to an antenna design. Starting from the original design, the file is appended each time a new better design is found. Here is an example, where the final line is the performance of the 4ele beam with the .dat file shown earlier.
1 7.57dBi, 16.93dB F/B, Z=(31.77-56.34j) Ohms, VSWR=3.95, SL=16.95 dB 84 7.58dBi, 16.93dB F/B, Z=(31.78-56.32j) Ohms, VSWR=3.95, SL=16.95 dB 623 7.58dBi, 16.93dB F/B, Z=(31.78-56.28j) Ohms, VSWR=3.95, SL=16.95 dB 89345 9.74dBi, 103.06dB F/B, Z=(37.55 +1.61j) Ohms, VSWR=1.33, SL=17.78 dB
The first column is an integer specifying the iteration. The other columns, going from left to right are gain(dBi), FB, input impedance, VSWR and level of the most significant sidelobe, in dB down on the peak gain.