HFAnt Utility

The purpose of HFAnt is to create, modify and save antenna data files to be used by the ITS HF Propagation prediction models; this of course includes VOACAP.

HFAnt is included in this install for user convenience.

HFAnt is reasonably easy to use and is ideal for adapting the antenna files used for predictions more closely match those used by a particular station.

The user should refer to the help file included with HFAnt for best success. However, we will attempt to step you through one antenna modification using the software. We will prefer the antennas of type ITSA-1 IONCAP. Pictures of these antenna structures are included in this help file for your convenience; see the list below.

HFAnt - Quick Start

Start the HFAnt software included in the "full install" of WinCAP Wizard as follows:

Click the windows start button, move the mouse cursor to the "WinCAP" group (the default group where WinCAP Wizard is installed), then click the HFAnt icon.

Click the "File" menu and then move to "New Type" move to the sub-menu item "ITSA-1 IONCAP" and click the item "Type23: Horizontal Dipole". Next time, the HFAnt software will open with the last antenna type with which you worked.

HFAnt provides seven buttons on the left, for the Horizontal Dipole.

1. For the "Description" item we recommend you leave as the default, at least until you are familiar with the HFAnt software.
2. The "File name" item is as you would expect, but it only assigns the actual name and does not save anything. Click the file name button. A standard windows file save dialog open and "points" into a special "parent folder" named "antennas". Do not move "up" in this folder structure. The VOACAP prediction engine expects antenna files to be somewhere under the antennas folder. You are free to "create" your own folder in the antennas parent folder, but we have provided one for your convenience named "station". Double click the folder icon named "station" to open. Now move to the edit box labeled "File name" and type a name for your custom dipole. We suggest you keep the name short, for example "dipole1.ant". Click the "save" button. Please note - the file still isn't saved. You must click the "Save as" button to the right of the file name button and answer yes to the prompt. No need to do this yet.
3. Click the "Change" button to the left of "Ground Dielectric Constant". A dialog window opens providing you with a list of ground types and look for the one that best describes your location - note the number to the right, in the column labeled "Dielectric". In the edit box, just below the "Accept" button, type the number you just noted and click the Accept button.
4. Change Ground Conductivity the same way you did above for dielectric, except use the number from the column labeled "Conductivity".
5. Change your Antenna Length if necessary. Note you can enter length using "wavelengths" by entering a "negative" number. This is the preferred way to begin.
6. Change Antenna Height as you did length above. Note actual height in meters is preferred.
7. If your dipole provides "gain above a 1/2 wave" dipole enter that gain.
8. Now click the "Save as" button and answer yes at the prompt.
9. Lets look at the antennas radiation pattern. From the menu, click "Plot pattern" and then click "Vertical". A dialog window appears requesting two items. Leave the first item as is and change the frequency in Megahertz to your favorite frequency. Click the Accept button.
10. Change some of the parameters of your dipole, probably one at a time, and look at the pattern again.
11. Lets try our new dipole in a prediction. Start WinCAP Wizard. This exercise expects you have already set up your geographic location. Click the "Circuits" button. In the Circuit-Configuration Manager, click the button labeled "Xmtr Antennas" to go to the transmit antennas page.
12. Lets create a new "antenna group" for our dipole. Recall, you can have as many antenna "groups" as you wish and select between them for predictions. Click the "+" button near the bottom of the Circuit-Configuration Manager - Xmtr Antennas page to create the new antenna group. Note - antenna "groups" are selected using the left and right "arrows".
13. Click the "Select" button to access the WinCAP Wizard Antenna Selector. In the left windowpane you will see the list of folders in the "antennas - parent folder" discussed above. Click the name of the folder where you saved your new dipole - "station" by default. Your dipole antenna file name and description will appear in the right windowpane. Double click the line in the right windowpane that represents your dipole - the Antenna Selector changes to the "Viewer" so you can see exactly what HFAnt wrote to the antenna file. The files are fairly simple, but the format needs to be precise.
14. Click the Antenna Selector "Done" button. You now have a circuit setup with a transmit antenna configured to more closely match yours.
15. Now you can create predictions that use your new antenna file. You might create two predictions to the same location to start, one using your new dipole and a second using the default Isotrope antenna. You can the compare the two predictions by switching back and forth. Hint, to change antennas, on the Xmtr Antennas page of the Circuit-Configuration Manager, use the "navigator" buttons near the bottom that look like left and right arrows to select between the two antennas.
16. Getting deeper, create a prediction batch with two identical circuits except for the transmit antenna. See the section "Things to Try With a Prediction Batch" for more ideas.

Antenna Selection or Design

For the frequency or frequencies under consideration, make predictions covering the required time period of operation using the Isotrope type antenna with a typical gain; perhaps 6 to 10 dB depending on the frequency. Determine the time or times the circuit reliability is the lowest. Using these times, repeat the computation for the antennas under consideration to select an antenna. Caution: the calculated vertical angle for the "most reliable mode" provides some guidance in determining the antennas to be considered, but this angle alone should never be used as the sole criterion for antenna selection. To select an antenna, repeat the computations for available antennas. To design an antenna, repeat computations for variables in the antenna design; for example antenna height, etc. Note -these parameters must be part of a "well designed" antenna.

The Antenna Patterns

The "antennas parent folder" includes two sub-folders by default. The standard antenna folders are named "samples" and "default". We have added a third folder, "station", for your convenience. Ignore the fourth folder named "windows.dat" - the HFAnt software uses it internally.

We begin our brief description with the "samples" folder. The first 12 patterns (samples 00-11) are derived from the CCIR Recommendation 705 (Rec705). Samples 21 through 30 are taken from the ITSA-1 program (Lucas and Haydon 1966), and are briefly described below. Samples 31 through 47 are pattern calculations from ITS-78 (also in HFMUFES) (Barghausen et al. 1969). There are some antennas in common in these last two groups, and some variations in computed gain. These "samples" may all be modified by using the HFAnt software and saving a new pattern, or file.

The second antennas folder, named "default", also contains a number of antenna pattern files. Only two may be of interest, "const17.voa" and "swwhip.voa".

The "const17.voa" pattern, in the defaults folder, is a hypothetical pattern for a typical horizontal dipole. The pattern has a 17-dBi gain at all angles from the zenith down to 3 degrees above the horizon. At angles from 3 degrees down to 0.1 degrees, the gain is reduced based on the reflection loss for a horizontally polarized antenna mounted at a height of one-half wavelength above perfect earth. The pattern is used for new circuits when the required take-off and arrival angle are unknown. This nearly perfect pattern allows the user to discover the angles required for best performance on a circuit.

The other antenna pattern included in the default is named "swwhip.voa". This is the pattern of a typical short whip antenna found on a portable HF receiver. This pattern has been validated with actual measurements - see the VOACAP documentation for more information.

The "ITSA-1 IONCAP" Antenna Structures -

Horizontal Rhombic structure (#21)

Vertical Monopole structure (#22)

Horizontal Dipole structure (#23)

Horizontal Yagi structure (#24)

Vertical Log Periodic structure (#25)

Curtain structure (#26)

Sloping Vee structure (#27)

Inverted L structure (#28)

Sloping Rhombic structure (#29)

Interlaced Rhombic structure (#30)

See the Basic Definitions & Standards section for additional information.