L-Band Antenna

Specifications

All parts 3D printed from PETG material, UV resistent and water proof.

 LHCP VariantRHCP Variant
Radiating Element3 turn left handed helix,
3.5mm copper wire
7 turn right handed helix,
3.5mm copper wire
Reception configurationConsumer type satellite dishDirect reception
Mounting OptionMounts in standard 40mm LNB clamp
(for offset dishes)
Universal mounting via 3 M4 bolts
(for prime focus dishes)
Universal mounting via 3 M4 bolts
DimensionsLength: 186mm, Diameter: 180mmLength: 374mm, Diameter: 180mm
ConnectorN-typeN-type
ApplicationsReception of geostationary satellite services, e.g.
Inmarsat, Iridium, digital telephony / data, digital weather pictures
Reception of geostationary and LEO satellites when mounted to el/az-rotor
Availabilitynolle.engineering (webshop)nolle.engineering (webshop)


RF Performance

LHCP, 3 windings

RHCP, 7 windings

Concept Renderings

LHCP vs RHCP mounting configurations

 

RHCP 7-turn variant. Helix wire is internally supported for stability. Radome can be removed (3D printed thread).

LHCP 3-turn variant. The reflector can be cut out to make space for the LNB arm depending on the antenna forward position.

RHCP Prototype

Individual solution for mast mounting (utilizing 40mm mounting option)

LHCP Prototype

Use Case

Architecture

See below an example on how to setup your L-Band receiver station. Signal is filter, amplified and digitized by software defined radio then provided to software receiver running on your local PC.

Filtering is optional, it might be necessary depending on your local RF environment (Wifi, LTE presense).

L-Band Receiver Architecture

Components

ComponentsDescriptionSource
(incl. 3rd party and affiliate links)
L-Band AntennaLHCP or RHCP as per your preferencesnolle.engineering (coming soon)
N-Type to SMA adapterAdapter from antenna to filter / LNA (N male to SMA male)
Bandpass FilterBlocking any interference from Wifi, LTE etc. improving signal strengthGPIO LABS 1525 to 1559 MHz Bandpass Filter
LNA (bias tee)

Low Noise Amplifier (LNA) and Saw Filter Module

1542MHz centre frequency

Powered via SMA output, requires SDR with bias-T.

 
LNA

Low Noise Amplifier (LNA) and Saw Filter Module

1542MHz centre frequency

Powered via micro USB 5V

 
SDR (bias tee)Software Defined Radio, including bias-T required to power LNA 
SMA InterconnectsSMA male to SMA male connecting between components 
SDR#SDR Softwarehttps://airspy.com/download/

Left: 3-turn LHCP on 1.5m prime focus dish (click to enlarge) vs. Right: 7-turn RHCP (direct reception)

Decoder Software

A list of popular INMARSAT and others deconding software packages:

  • https://tekmanoid.com/egc
  • https://github.com/jontio/JAERO/releases

Web SDR Demo

23.10.2022: I am operating a live web SDR with the LHCP version on a 80cm offset dish. It is located at JN58UA and currently pointed towards Alphasat tuned to 1541.1 MHz with 2MHz bandwidth.

Click on the image to test the receiver. It is fully interactive: