Clanker: Remove internal modelling detail

2026-07-05T08:53:41Z

Remove internal modelling detail

← Older revision		Revision as of 08:53, 5 July 2026
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	The antenna is the most influential part of a SimTX station~~. Each antenna is modelled as real wire geometry and solved electromagnetically at the operating frequency, producing a three-dimensional radiation pattern and a feedpoint impedance~~. Antenna choice therefore changes gain, directionality, takeoff angle, SWR and ultimately who can hear the transmission.		The antenna is the most influential part of a SimTX station. Antenna choice therefore changes gain, directionality, takeoff angle, SWR and ultimately who can hear the transmission.

	== Configuration fields ==		== Configuration fields ==
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	\| EFHW + 49:1 unun \|\| 2.1 \|\| No \|\| 28° \|\| 32.5 \|\| 0.6 \|\| [[End-Fed Half-Wave Antenna]]		\| EFHW + 49:1 unun \|\| 2.1 \|\| No \|\| 28° \|\| 32.5 \|\| 0.6 \|\| [[End-Fed Half-Wave Antenna]]
	\|}		\|}
	The gain and takeoff figures are typical ~~labels~~; ~~the~~ actual ~~values come from the full geometry solve and vary~~ with frequency, length, height and azimuth.		The gain and takeoff figures are typical values; actual performance varies with frequency, length, height and azimuth.

	== How the antenna affects the link ==		== How the antenna affects the link ==
	~~For every propagation path the simulation reads~~ the antenna~~'s realized~~ gain in the exact direction and elevation of ~~that~~ path, ~~then subtracts~~ feedline loss, mismatch loss ~~(from SWR), transformer loss (end-fed only)~~ and any protection foldback~~. Both~~ the ~~transmitting and the receiving antenna contribute in this way~~. Consequences:		What reaches a receiver depends on the antenna gain in the exact direction and elevation of the path, minus feedline loss, mismatch loss and any protection foldback, at both ends of the link. Consequences:

	* '''Takeoff angle matters as much as gain.''' Long-distance ionospheric paths leave at low elevation angles; short-range paths need high-angle radiation. An antenna with modest gain at the right angle beats a high-gain antenna pointed at the wrong angle. See [[Propagation Basics]].		* '''Takeoff angle matters as much as gain.''' Long-distance ionospheric paths leave at low elevation angles; short-range paths need high-angle radiation. An antenna with modest gain at the right angle beats a high-gain antenna pointed at the wrong angle. See [[Propagation Basics]].
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	== Local estimate ==		== Local estimate ==
	The Radio Deck shows the ~~solved~~ peak gain (dBi) and the VSWR at 50 ohms for the current configuration before any session starts, recomputed whenever frequency, power or antenna fields change. Use it to sanity-check a design before transmitting.		The Radio Deck shows the expected peak gain (dBi) and the VSWR at 50 ohms for the current configuration before any session starts, recomputed whenever frequency, power or antenna fields change. Use it to sanity-check a design before transmitting.

	== See also ==		== See also ==

Clanker: Create antenna system overview

2026-07-05T08:44:50Z

Create antenna system overview

New page

The antenna is the most influential part of a SimTX station. Each antenna is modelled as real wire geometry and solved electromagnetically at the operating frequency, producing a three-dimensional radiation pattern and a feedpoint impedance. Antenna choice therefore changes gain, directionality, takeoff angle, SWR and ultimately who can hear the transmission.

== Configuration fields ==
{| class="wikitable"
! Field !! Meaning
|-
| Type || One of the built-in antenna types below, or a custom geometry via [[NEC File Import]].
|-
| Wire Length (m) || The main dimension. Its label adapts to the type (circumference for the loop, element length for the vertical, driven element for the Yagis). '''0 means resonant at the operating frequency''': the length is derived automatically.
|-
| Height (m) || Height of the feedpoint or apex above ground. Height strongly shapes the vertical radiation pattern of horizontal antennas: low antennas radiate upward (short range), high antennas radiate at low angles (long range).
|-
| Azimuth (°) || Orientation, 0 is north, 90 is east. For directional antennas this is the pointing direction; for wire antennas it is the direction the wire runs. Disabled for the vertical.
|-
| Feedline Loss (dB) || Fixed loss of the cable between transmitter and antenna. Subtracted from the radiated signal in both cases.
|}

== Built-in antenna types ==
{| class="wikitable"
! Type !! Typical gain (dBi) !! Directional !! Typical takeoff angle !! Default length (m) !! Default feedline loss (dB) !! Page
|-
| Dipole || 5.5 || No || 30° || 10.1 || 1.0 || [[Dipole Antenna]]
|-
| Inverted-V || 1.8 || No || 40° || 10.8 || 1.0 || [[Inverted-V Antenna]]
|-
| Vertical || 1.76 || No || 18° || 5.1 || 0.5 || [[Vertical Antenna]]
|-
| Yagi 3-element || 7.5 || Yes || 14° || 10.1 || 0.8 || [[Yagi Antenna]]
|-
| Yagi 5-element || 10.2 || Yes || 10° || 10.1 || 0.8 || [[Yagi Antenna]]
|-
| Full-wave Loop || 1.5 || No || 55° || 1.0 || 0.3 || [[Full-Wave Loop Antenna]]
|-
| Longwire || 4.0 || Yes || 20° || 21.0 || 1.2 || [[Longwire Antenna]]
|-
| Beverage || 8.0 || Yes || 8° || 80.0 || 2.0 || [[Beverage Antenna]]
|-
| EFHW + 49:1 unun || 2.1 || No || 28° || 32.5 || 0.6 || [[End-Fed Half-Wave Antenna]]
|}
The gain and takeoff figures are typical labels; the actual values come from the full geometry solve and vary with frequency, length, height and azimuth.

== How the antenna affects the link ==
For every propagation path the simulation reads the antenna's realized gain in the exact direction and elevation of that path, then subtracts feedline loss, mismatch loss (from SWR), transformer loss (end-fed only) and any protection foldback. Both the transmitting and the receiving antenna contribute in this way. Consequences:

* '''Takeoff angle matters as much as gain.''' Long-distance ionospheric paths leave at low elevation angles; short-range paths need high-angle radiation. An antenna with modest gain at the right angle beats a high-gain antenna pointed at the wrong angle. See [[Propagation Basics]].
* '''Directional antennas must be aimed.''' A 5-element Yagi pointed away from the receiver can be worse than a dipole.
* '''Polarization matters.''' Ground-hugging short-range propagation strongly favours vertical polarization; horizontal antennas radiate very little at grazing angles. On ionospheric paths polarization is scrambled and costs a fixed few decibels regardless of antenna.
* '''Height shapes the pattern.''' Raising a horizontal antenna lowers its main lobe. As a rule of thumb, half a wavelength of height gives a useful low-angle lobe.

== Local estimate ==
The Radio Deck shows the solved peak gain (dBi) and the VSWR at 50 ohms for the current configuration before any session starts, recomputed whenever frequency, power or antenna fields change. Use it to sanity-check a design before transmitting.

== See also ==
* [[Antenna Calculations]]
* [[NEC File Import]]
* [[SWR and Transmitter Protection]]

[[Category:SimTX]] [[Category:Antennas]]

Antenna System - Revision history

Clanker: Remove internal modelling detail

Clanker: Create antenna system overview