Antennas and siting - Revision history

ScotMesh: Drop the 433 MHz profile: it has been scrapped, ScotMesh is 868 MHz only

2026-09-17T12:36:35Z

Drop the 433 MHz profile: it has been scrapped, ScotMesh is 868 MHz only

← Older revision		Revision as of 13:36, 17 September 2026
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	== The antenna must match the band ==		== The antenna must match the band ==

	An antenna is tuned for a frequency range. ~~A 433 MHz~~ antenna on an 868 MHz board ~~(or the other way round)~~ reflects most of the transmitter's power back into it: range collapses, and at 22 dBm the radio can be damaged. Check the band printed on the antenna, and '''never transmit with no antenna connected'''.		An antenna is tuned for a frequency range. An antenna made for another band on an 868 MHz board reflects most of the transmitter's power back into it: range collapses, and at 22 dBm the radio can be damaged. Check the band printed on the antenna, and '''never transmit with no antenna connected'''.

	Cheap boards often ship with a generic stub that is not tuned for ~~either band~~. Replacing it is the single best upgrade.		Cheap boards often ship with a generic stub that is not tuned for 868 MHz at all. Replacing it is the single best upgrade.

	{\| class="wikitable"		{\| class="wikitable"
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	\| Stub or “rubber duck” \|\| 0 to 2 dBi \|\| Handhelds and testing on a desk		\| Stub or “rubber duck” \|\| 0 to 2 dBi \|\| Handhelds and testing on a desk
	\|-		\|-
	\| Quarter-wave whip (~~433: about 16.5 cm; 868:~~ about 8.2 cm) \|\| about 2 dBi \|\| Cheap, easy, works well with a ground plane (a metal box lid or a few radials)		\| Quarter-wave whip (about 8.2 cm at 868 MHz) \|\| about 2 dBi \|\| Cheap, easy, works well with a ground plane (a metal box lid or a few radials)
	\|-		\|-
	\| Half-wave dipole \|\| about 2 dBi \|\| Needs no ground plane; a good indoor or window antenna		\| Half-wave dipole \|\| about 2 dBi \|\| Needs no ground plane; a good indoor or window antenna
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	== Cable and connectors ==		== Cable and connectors ==

	Coaxial cable loses signal, more at ~~868 MHz than at 433~~, and thin cable loses most. Ten metres of RG174 at 868 MHz throws away roughly half the power; ten metres of LMR-400 loses almost nothing. Keep the run short, use decent cable (LMR-240 or better for anything over a few metres), and put the radio near the antenna if you can: a [[ScotMesh firmware\|standalone node]] in a box at the top of the pole with a short tail to the antenna beats a long feeder to a radio indoors.		Coaxial cable loses signal, more at higher frequencies, and thin cable loses most. Ten metres of RG174 at 868 MHz throws away roughly half the power; ten metres of LMR-400 loses almost nothing. Keep the run short, use decent cable (LMR-240 or better for anything over a few metres), and put the radio near the antenna if you can: a [[ScotMesh firmware\|standalone node]] in a box at the top of the pole with a short tail to the antenna beats a long feeder to a radio indoors.

	Connectors: most boards have a u.FL or IPEX socket; most antennas have an SMA plug. Check whether you need SMA or '''RP-SMA''' (reverse polarity; common on Wi-Fi kit); they look alike and do not mate. Every adapter is a small loss and a place for water to get in.		Connectors: most boards have a u.FL or IPEX socket; most antennas have an SMA plug. Check whether you need SMA or '''RP-SMA''' (reverse polarity; common on Wi-Fi kit); they look alike and do not mate. Every adapter is a small loss and a place for water to get in.
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	== Two power notes ==		== Two power notes ==

	* The licence-free bands limit both transmit power and how much of the time you may transmit. The ScotMesh ~~profiles are~~ within those limits; adding a high-gain antenna raises your effective radiated power, so do not pair the 22 dBm profile with a high-gain directional antenna without checking the rules for the band.		* The licence-free bands limit both transmit power and how much of the time you may transmit. The ScotMesh profile is within those limits; adding a high-gain antenna raises your effective radiated power, so do not pair the 22 dBm profile with a high-gain directional antenna without checking the rules for the band.
	* Transmit power is the least effective knob. If a link is marginal, raise the antenna, shorten the cable or move the node before raising the power.		* Transmit power is the least effective knob. If a link is marginal, raise the antenna, shorten the cable or move the node before raising the power.

ScotMesh: Point people at the ScotMesh Discord first

2026-09-11T15:00:31Z

Point people at the ScotMesh Discord first

← Older revision		Revision as of 16:00, 11 September 2026
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	== Share what you find ==		== Share what you find ==

	Real results from real sites in Scotland are worth more than any of the above. When you measure a link, note the two sites, antennas, heights and the RSSI and SNR reported by <code>rnstatus</code> or the node's page, and put them on the [https://~~scotmesh~~.~~uk forum~~] or add them here.		Real results from real sites in Scotland are worth more than any of the above. When you measure a link, note the two sites, antennas, heights and the RSSI and SNR reported by <code>rnstatus</code> or the node's page, and put them on the [https://discord.gg/ytxfyuDmSt ScotMesh Discord] or add them here.

	[[Category:Hardware]]		[[Category:Hardware]]

ScotMesh: Added after the move to MediaWiki

2026-09-11T14:49:49Z

Added after the move to MediaWiki

@@ Line 1: / Line 1: @@
-''Outline — the shape of the page, not the page. Expand or replace freely.''
+The antenna and where you put it make more difference to range than the radio does. A good antenna on a roof with a poor board will outperform the best board on a desk with the stub antenna it came with, every time. This page is the practical version for ScotMesh's two bands.
-The part that makes more difference than the radio does.
+== The antenna must match the band ==
-== To cover ==
+An antenna is tuned for a frequency range. A 433 MHz antenna on an 868 MHz board (or the other way round) reflects most of the transmitter's power back into it: range collapses, and at 22 dBm the radio can be damaged. Check the band printed on the antenna, and '''never transmit with no antenna connected'''.
-* Matching the antenna to the band
+Cheap boards often ship with a generic stub that is not tuned for either band. Replacing it is the single best upgrade.
-* Height, line of sight, and what actually limits range
-* Feeder loss and connectors
+{| class="wikitable"
-* Practical results from around Scotland — real figures beat theory
+! Type !! Gain !! Good for
 [[Category:Hardware]]

ScotMesh: Imported from the BookStack wiki (backup 2026-09-11)

2026-09-11T14:49:08Z

Imported from the BookStack wiki (backup 2026-09-11)

New page

''Outline — the shape of the page, not the page. Expand or replace freely.''

The part that makes more difference than the radio does.

== To cover ==

* Matching the antenna to the band
* Height, line of sight, and what actually limits range
* Feeder loss and connectors
* Practical results from around Scotland — real figures beat theory

[[Category:Hardware]]