Difference between revisions of "Antennas"

From SatNOGS
(Update names/design file/assembly instruction links for helical antenna to reflect new URLs)
(Expanded page to include non rotator ground stations)
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Antennas developed and used by SatNOGS rotators
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<p><strong>Antennas for your ground station</strong></p>
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<p>The type of antenna largely depends on the type of ground station. A no rotator ground station will benefit from a different type of antenna to a rotator based ground station. The two different approaches are explored below. In addition to the choice of antenna the choice of location for the ground station will have an effect on the quality of observations.</p>
  
==SatNOGS antennas==
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<p>&nbsp;</p>
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<p><strong>Non-Rotator Ground Station</strong></p>
  
To cover the needs of the SatNOGS community the SatNOGS team has developed a number of antennas.
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<p>This type of ground station will require an antenna that will give a broad coverage from its fixed position. It is therefore not just the antenna that needs to be considered but also the proximity of buildings, geography or metallic structures that might be in the path of a line of sight between the ground station and satellite.</p>
  
===Yagi===
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<p>Typical ground stations have had success with simple wire antennas that can be commercially bought or made at home. Colinear or &lsquo;white stick&rsquo; antennas are vertically polarised omnidirectional antennas. These have anecdotally been used for successful satellite work but should be avoided. The following are considered suitable choices:</p>
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<p>&nbsp;</p>
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<ul>
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<li>[https://en.wikipedia.org/wiki/Turnstile_antenna Turnstile Antenna]. The SatNOGS design is [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/Turnstile here].
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</li>
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<li>[http://www.g4ilo.com/qfh.html Quadrafila Helix Antenna (QFH) ]</li>
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<li>[http://www.amsat.org/articles/w6shp/lindy.html Lindenblad]</li>
  
A Yagi antenna is the simplest antenna for the novice maker.
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</ul>
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<p>&nbsp;</p>
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<p><strong>Rotator Ground Station</strong></p>
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<p>A rotator based ground station is able to make use of directional antennas. These will have a directional gain, meaning that you will need to point them in the direction of the satellite but the signal you receive will be stronger and for longer. They will allow much lower to the horizon passes to be received and more successful observations. These are not complex antennas but the choice will depend on the type of satellite and there are variations on the main types. Yagi, helical and quad.</p>
 +
<ul>
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<li>Yagi antennas. &ndash; A common type of antenna that is either horizontally or vertically polarised. Simple to construct and suitable for a large number of satellites. Designs for the SatNOGS versions for VHF and UHF are here [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/Yagi here].</li>
 +
<li>Helical antennas &ndash; A less common type that are &lsquo;handed&rsquo;. The antenna looks a bit like a corkscrew and can be either LHCP (Left hand circular polarisation) or RHCP (right hand circular polarisation). The SatNOGS designs are [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/Helical here].</li>
 +
<li>Quad antennas &ndash; This type of antenna has a square appearance and have electrically switchable polarisation, some types will be horizontal, vertical or circularly polarised. No SatNOGS designs currently exist for this type of antenna.</li>
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</ul>
  
===Cross Yagi UHF v1===
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<p>For reference the NEC files for modelling of the antennas is also available from [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/NEC The Git Repository].
  
A cross Yagi UHF antenna.
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<p>&nbsp;</p>
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<p><strong>Constructing the SatNOGS antennas.</strong></p>
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<p>Guides are available for construction the SatNOGS designs. The Yagi antennas are simpler and require no specialist tools whilst the helical antenna will need access to milling and turning equipment.</p>
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<ul>
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<li>Yagi construction guide (Construction guide required)</li>
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<li>UHF helical antenna construction guide &ndash; [https://ohai.satnogs.org/project/helical-antenna-v5/hardware/ V5 Design]</li>
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</ul>
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<p>&nbsp;</p>
  
* [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/Yagi/Cross-Yagi-UHF-v1 v1 Design files]
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<p><strong>SatNOGS Radome</strong></p>
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<p>A radome design is available from SatNOGS. This will protect the ground station from the elements in all but extra ordinary conditions. The design can be found [https://gitlab.com/librespacefoundation/satnogs/satnogs-radome/blob/master/satnogs-radome-v1-bom.ods here] and construction guide [https://ohai.satnogs.org/project/satnogs-radome-v1/hardware/ here].&nbsp;</p>
  
===Helical v1===
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<p>&nbsp;</p>
 
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<p><strong>Commercial Antennas</strong></p>
The first iteration of our helical UHF antenna allows users to create their own helical antenna design using only 3D printed parts.  It is tuned for 437 MHz.
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<p>An alternative to home made antennas is to buy a commercial type. These can be expensive and will, in general, not offer significant improvements over well constructed homebrew antenna. Bothe the Arrow [http://www.arrowantennas.com/arrowii/146-437.html Arrow II Satellite Antenna] and Elk antennas [https://elkantennas.com/product/dual-band-2m440l5-log-periodic-antenna/ Log Periodic] are commonly used for ground stations as well as the [http://www.wimo.com/xquad-antennas_e.html Wimo X Quad Antenna's]</p>
 
 
* [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/Helical/UHF%20lhcp-version_1 Design files]
 
 
 
* [https://ohai.satnogs.org/workflow/helical-antenna-v1/hardware/ Assembly instructions]
 
 
 
===Helical v4===
 
 
 
This iteration is more rigid, but you need to have access to CNCed parts.
 
 
 
* [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/Helical/UHF-434-8-version_4 Design files]
 
 
 
* [https://satnogs.dozuki.com/Guide/Helical+Antenna+v4/11 Assembly instructions]
 
 
 
===Helical v5===
 
 
 
This iteration is our latest version of the Helical antenna design; it comes in RHCP configuration.  The supports are made from aluminum, and will require a drill press.
 
 
 
* [https://gitlab.com/librespacefoundation/satnogs/satnogs-antennas/tree/master/Helical/UHF-435-8-version_5 Design files]
 
 
 
* [https://ohai.satnogs.org/project/helical-antenna-v5/hardware/ Assembly instructions]
 
 
 
==Commercial Antennas==
 
 
 
===[http://www.arrowantennas.com/arrowii/146-437.html Arrow II Satellite Antenna]===
 
 
 
==DIY Antenna designs==
 

Revision as of 15:23, 4 December 2017

Antennas for your ground station

The type of antenna largely depends on the type of ground station. A no rotator ground station will benefit from a different type of antenna to a rotator based ground station. The two different approaches are explored below. In addition to the choice of antenna the choice of location for the ground station will have an effect on the quality of observations.

 

Non-Rotator Ground Station

This type of ground station will require an antenna that will give a broad coverage from its fixed position. It is therefore not just the antenna that needs to be considered but also the proximity of buildings, geography or metallic structures that might be in the path of a line of sight between the ground station and satellite.

Typical ground stations have had success with simple wire antennas that can be commercially bought or made at home. Colinear or ‘white stick’ antennas are vertically polarised omnidirectional antennas. These have anecdotally been used for successful satellite work but should be avoided. The following are considered suitable choices:

 

 

Rotator Ground Station

A rotator based ground station is able to make use of directional antennas. These will have a directional gain, meaning that you will need to point them in the direction of the satellite but the signal you receive will be stronger and for longer. They will allow much lower to the horizon passes to be received and more successful observations. These are not complex antennas but the choice will depend on the type of satellite and there are variations on the main types. Yagi, helical and quad.

  • Yagi antennas. – A common type of antenna that is either horizontally or vertically polarised. Simple to construct and suitable for a large number of satellites. Designs for the SatNOGS versions for VHF and UHF are here here.
  • Helical antennas – A less common type that are ‘handed’. The antenna looks a bit like a corkscrew and can be either LHCP (Left hand circular polarisation) or RHCP (right hand circular polarisation). The SatNOGS designs are here.
  • Quad antennas – This type of antenna has a square appearance and have electrically switchable polarisation, some types will be horizontal, vertical or circularly polarised. No SatNOGS designs currently exist for this type of antenna.

For reference the NEC files for modelling of the antennas is also available from The Git Repository.

 

Constructing the SatNOGS antennas.

Guides are available for construction the SatNOGS designs. The Yagi antennas are simpler and require no specialist tools whilst the helical antenna will need access to milling and turning equipment.

  • Yagi construction guide (Construction guide required)
  • UHF helical antenna construction guide – V5 Design

 

SatNOGS Radome

A radome design is available from SatNOGS. This will protect the ground station from the elements in all but extra ordinary conditions. The design can be found here and construction guide here

 

Commercial Antennas

An alternative to home made antennas is to buy a commercial type. These can be expensive and will, in general, not offer significant improvements over well constructed homebrew antenna. Bothe the Arrow Arrow II Satellite Antenna and Elk antennas Log Periodic are commonly used for ground stations as well as the Wimo X Quad Antenna's