portable-antennas - Doublet antenna designer

Use the controls on the left-hand side to configure your antenna - set the design frequency, antenna element lengths and angles, wire diameter, wire insulation if required, support height, etc.
When you are happy with your configuration, press the "Show antenna" button to display your antenna in interactive 3D graphics mode in the area on the right-hand side. Each time you change your configuration, you should press the "Show antenna" button to register the changes to the app.
After you have configured your antenna, you can then use the controls further down in the page to generate charts and diagrams to evaluate the antenna's performance - you will need to scroll down in the page to access these controls.
You can choose to view any combination of the available charts and diagrams: these include four radiation pattern types: azimuth, elevation, 3D and polarization patterns; other options include VSWR charts, an antenna currents diagram, and a Smith chart.

Set antenna color: Show person-height plane

Principal band
Band:
Frequency:	kHz
Nominal ½ λ:	m Corrected ½ λ: m
Custom length:	Specify a length: m
Antenna wire
Wire core:	diameter
Material:
Insulation:	thickness
Ins. type:	Corr. factor:
Antenna center height, apex angle
Center height:	m
½ -apex angle:
Balanced feeder line
Line type:
Line length:	m
Conductor ⌀:	mm
Material:	Copper, or copper-clad steel
Spacing:	mm
Line impedance:	Ω ( Calculated or derived )
Velocity factor:	( Estimated or derived )

Antenna overview

Section lengths (m)

Center
height (m)

Apex
angle (°)

Horizontal
span (m)

Length (m)

Doublet antenna designer

Use the controls on the left-hand side to configure your antenna.
When you are happy with your configuration, press the "Show antenna" button to display your antenna in interactive 3D graphics mode in this area.
After you have configured your antenna, you can then use the controls further down in the page to generate charts and diagrams to evaluate the antenna's performance ...

portable-antennas.com

Antenna feed-point: ⬥

Show interactivity hints:

Antenna performance

Here you can generate plots of radiation patterns, VSWR chart, antenna currents diagram and Smith chart for your antenna over a choice of ground types. By changing the physical dimensions of the antenna, and refreshing these plots, you can learn a lot about how such antennas will perform in the field.
Please note that radiation patterns are here modelled over flat ground - when the antenna is erected on a hill-top or mountain summit, the surrounding sloping ground will generally cause angles in the elevation radiation pattern to be lowered in the direction of the slope: the steeper the slope, the lower the effective elevation take-off angle will be, and the better the chances of making long-distance contacts. Read more...

Antenna: Configuration: Frequency: GenID:

Antenna
plane
0° - 180°

Azimuth:
Gain:
Beamwidth:	N/A
(At elevation angle: 133°)

Elevation:
Gain:
Beamwidth:	N/A
(At azimuth angle: 133°)

General parameters (at 7.000 MHz)

Outer ring:	5.23 dBi
VSWR:	2.06 : 1
Unun ratio:	49 : 1
Feed-point Z:	5125 - j1983 Ω
Transformed Z:	xxx

Show selected azimuth/elevation slices in 3D plot

How to use these diagrams » » »

VP2E antenna designer - correction factors reference

Length-correction factor used in this application (applied automatically)

VP2E antenna impedances, plotted against feed-point position
End-effect multiplication factor - dependent on wire diameter and frequency

VP2E antenna impedances

This curve is for a 20-meter VP2E antenna, with apex angle 140°, foot height 0.030 and variable FP position, set up over average ground. This is a typical set-up for this kind of antenna.

As can be seen from the chart, the lowest impedance measured is about 85 Ω, and never reaches the 50 Ω which some claim for the VP2E antenna. The curve closely mirrors the standing-wave current distribution in either of the two arms of the antenna, which varies smoothly along the wire.

VP2E antenna impedances :

End effect multiplication factor

Wavelength / wire diameter ratio, λ/d:

End-effect multiplication factor :

Save antenna configuration

Give your antenna configuration a meaningful title...

Title:

Manage saved antenna configurations

Your saved antenna configurations:

Click on
an antenna
configuration
to select it

Double-click
to load a
configuration

You may choose an example from the list and import it into your "Favourites" list

Title	Band	Freq. kHz	Units	Wire Dia.	Supp. Ht.	Section #1			Section #2
Title	Band	Freq. kHz	Units	Wire Dia.	Supp. Ht.	%	Length	Angle	%	Length	Angle
Some title	40m	7000	m	1	1	1	1	1	1	1	1

Coordinates can be used to model the same antenna in a separate program

Freq. (MHz)	FP pos. (λ)	Apex angle	Foot ht. (λ)	Section #	Section length (m)	Section coordinates (m)
Freq. (MHz)	FP pos. (λ)	Apex angle	Foot ht. (λ)	Section #	Section length (m)	x1	z1	x2	z2
7.000	0.240	140°	0.040	1	3.426	1	1	1	1
				2	6.214	1	1	1	1
				3	10.472	1	1	1	1

Copy this CSV text and paste into your favorite spreadsheet program

Export antenna dimensions to file

Export format:
Antenna diagram:	Use original view Use current view
PDF options: Toggle all	Include radiation patterns Include VSWR chart Include currents diagram Include Smith chart If you include any of these options, make sure you refresh the required radiation patterns, charts and diagrams for your antenna before exporting.
Collecting data:	0 %

Smith chart impedances

Table of selected impedances charted in the Smith chart, listed by frequency.

Show data for: All frequencies Band-center frequencies Info

Band	Frequency MHz	Antenna feed-point			Feed-line tuner-end
Band	Frequency MHz	R Ω	X Ω	VSWR	R Ω	X Ω	VSWR
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-
-	-	-	-	-	-	-	-

VP2E antenna designer

Combined azimuth + elevation patterns

Using combined azimuth + elevation patterns

The new combined azimuth and elevation patterns diagrams are fully interactive, allowing dynamic re-plotting of the patterns. You can choose any one of the following levels of interactivity:

No interaction
- the diagrams remain fixed at their default azimuth and elevation cuts.
Hover the mouse over the circular region in one diagram
- a green radial line and marker pair will appear in the diagram;
- the line and marker will follow the mouse around the diagram;
- angle and gain values at the mouse position are updated in the texts directly below the diagram.
Click within the circular region in one diagram
- the radial axis (the black line with numbers) is re-positioned to the selected angle;
- this new radial-axis position defines a new "slice" through the 3D radiation-patterns data;
- the other diagram is then re-plotted to reflect the new slice through the data;
- if the 3D radiation-pattern diagram is visible, then it too will be re-plotted to reflect the new slice through the data.
Click and drag within the circular region in one diagram
- the radial axis follows the mouse position in that diagram continuously;
- releasing the mouse fixes the radial axis at the selected angle;
- a new slice through the 3D radiation-patterns data is generated;
- the other diagram is then re-plotted to reflect the new slice through the data.
- if the 3D radiation-pattern diagram is visible, then it too will be re-plotted to reflect the new slice through the data.

All these different levels of interactivity are not just for show - they are designed to engage your curiosity about azimuth, elevation and 3D patterns and curves, and to help you learn about them.

By using the different levels of interactivity, you should gain a deeper insight into how each of the patterns and curves are intimately connected. Change one, and the other two are affected.

How deeply you venture into this, is entirely up to you: the tools are provided for you to use.

Choose ground type of land in the vicinity of the antenna:	Conductivity: S/m Dielectric const.: F/m
View radiation patterns:	Azimuth + Elevation Polarization patterns
	3D pattern Choose type: Classic 3D plot
Set ref. elevation angle:	Auto Choose:
Set ref. azimuth angle:	Auto 0° (inline) 90° (broadside)
Radiation patterns for:	Principal band only Choose band:
Impedance transformer:	current balun (at lower end of ladder-line)
View VSWR chart:	VSWR Check on: Chosen band Bands range From: To:
View currents diagram:	Antenna currents diagram
View Smith chart:	Smith chart
Antenna gains at 0° elevation:
Antenna FP impedance:
Tuner-end impedance:
Estimated bandwidth:

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