Antenna Design
Learn to model your own antenna designs.

MMANA Antenna Modeling Program Tutorial, Part 5

A Quick Halfwave-Dipole Modeling Example

A Quick Halfwave-Dipole Modeling Example
To see how the geometry screen is used, check the lambda box in theupper-right-hand corner of the program window. That will change the element-length unit-of-measure from the meters program default to wavelength, so we can quickly model a halfwave dipole without having to calculate its length in meters. Notice when you check that box that the spreadsheet column labels change from containing (m) to containing (wl) as a reminder that element dimensions are to be specified in wavelength, rather than in meters, as shown below:

MMANA geometry screen with lambda selected
MMANA geometry screen with the lambda element length option selected

Antenna Frequency
We could model a halfwave dipole for any frequency, but the purpose of this demonstration leave the frequency set to the 14.050 MHz MMANA default frequency.

X and Y Element Directions
Antenna elements can be described in terms of Y and Y directions. X and Y are any two arbitrary directions in azimuth that are orthogonal (at right angles) to each other. For example, we could arbitrarily decide that the X direction runs east and west and that the Y direction runs north and south. However, it isn't necessary that an antenna description be aligned with compass points. We could decide that the X direction is the direction between two oak trees that are going to support an antenna wire and that the Y direction is the azimuth direction that will be at right-angles to that wire.

Z Element Direction
The Z element direction is always the direction that is normal to earth (in other words, orthogonal to a line that is tangent to earth or vertical to the local earth surface).

Describe the Halfwave Dipole Numerically
The No, X1, Y1, Z1, X2, Y2, Z2, R and Seg labels across top of the empty spreadsheet fields have the following meanings:

Geometry-Screen Column Labels
LabelLabel Meaning
NoThe "No" column will contain antenna element numbers. MMANA automatically numbers each antenna element described to provide a means of element identification.
X1One end of an antenna element that runs in the X direction
Y1One end of an antenna element that runs in the Y direction
Z1One end of an antenna element that runs in the Z direction
X2The other end of an antenna element that runs in the X direction
Y2The other end of an antenna element that runs in the Y direction
Z2The other end of an antenna element that runs in the Z direction
RThe radius of an antenna element.
SegA code number that specifies how the antenna element is to be segmented when calculating antenna characteristics (more about this later).

Search other ham radio sites with Ham Radio Search