EDX Antenna Pattern File Format

Here is a description of our pattern file format. The .PAT folder inside the program on the hard drive contains examples. Instructions are alos available in Appendix I of the EDX reference manual.

This file is a tabulation of azimuths and relative field or dB values that describe a directional antenna pattern. Both horizontal and vertical plane pattern values can be listed in the file. The format of this file is as follows:

  • ‘Antenna Type’, GAIN, KYPAT
  • AZR(1), HP(1) AZR(2), HP(2) . . . AZR(NR), HP(NR)
  • 999
  • NUM_SLICES, NELV
  • NELV AZ_SLICE(1)
  • EL(1,1) VP(1,1) EL(1,2), VP(1,2) . . . EL(1,NELV), VP(1,NELV)
  • AZ_SLICE(2)
  • EL(2,1), VP(2,1) EL(2,2), VP(2,2) . . . EL(2,NELV), VP(2,NELV)
  • AZ_SLICE(3) EL(3,1), VP(3,1) EL(3,2), VP(3,2) . . . EL(3,NELV), VP(3,NELV) . . . .
  • AZ_SLICE(NUM_SLICES) EL(NUM_SLICES,1), VP(NUM_SLICES,1) EL(NUM_SLICES,2), VP(NUM_SLICES,2) . . . EL(NUM_SLICES,NELV), VP(NUM_SLICES,NELV)

‘Antenna Type’ is the name of the antenna. It must be no more than 20 characters in length and enclosed in single quotation marks. This name is only used to identify the file; it is not used by the program.
GAIN – the maximum gain of the antenna in dBi. This number is not used by the program for the co-polarized antenna file. Instead, the program normalizes the pattern maximum to the maximum ERP for the transmitter. For cross-polarized antenna patterns this number is the amount of cross-polarization rejection in dB.
KYPAT – the key number which indicates whether the following tabulated pattern data is in relative field or dB. KYPAT=1 for relative field; KYPAT=2 for dB.
AZR – azimuth from 0 to 360 degrees on which the horizontal plane pattern value is specified. These need to be in ascending order in the file. Maximum azimuth increment = 45∞.
HP – horizontal plane pattern value in relative field as a decimal fraction, or dB, depending on the value of KYPAT.
NR – total number of azimuths listed in the file. The maximum number of horizontal plane pattern points which may be listed is 721.
999 – a special code which separates the horizontal plane from the vertical plan antenna data.
NUM_SLICES – number of vertical plane pattern azimuth “slices” or descriptions which follow in the file. Maximum value = 72.
NELV – number of vertical plane pattern values that are specified for each azimuth slice. Maximum value = 181. Each azimuth slice must also use the same set of vertical plane elevation angles.
AZ_SLICE – the azimuth in degrees for which the following vertical plane pattern points is taken. Value must be between 0 and 360 degrees, inclusive.
EL – elevation angle between 180 and -180 degrees on which the vertical plane pattern value is specified. These angles begin above the horizon (positive) and progress to below the horizon (negative).
VP – vertical plane pattern value in relative field as a decimal fraction, or dB, depending on the value of KYPAT.

The structure given above is in generic variable name array notation. In preparing the file, actual, numbers are used in place of the variable names. A comma and/or spaces can be used to separate the fields on each line. So that the program can properly normalize the values for internal use, the azimuth and elevation with the maximum pattern value in each case must be included in the file. The file can take any name desired. For consistency we recommend that .pat be used as the file name extension but this is not absolutely necessary. Pattern information that defines the relative shape of the antenna pattern with regard to a cross-polarized signal should be entered as a separate data file using the above format. The amount of cross-polarization rejection for this pattern should be entered as the GAIN variable. This is a positive number representing rejection (15-20dB is typical). The name of this data file is identical to the name of the co-polarized file except that the extension .xpol is added. For example: if the co-polarized pattern is in a file “sample.pat” the cross-polarized pattern would be in a file called sample.pat.xpol. When an .xpol antenna file exists, the “Cross-polarized Rejection” value found in that transmitter or receiver Antenna Specifications is not used since that value is already in the .xpol file. All values for pattern gain (HP, VP) in the file can either be absolute gain or relative gain. The program normalizes each plane to the maximum value entered and then combines the various relative gains at the appropriate azimuths and elevations to give the relative gain in that direction.