Schematic network canvas
Place base stations, head ends, amplifiers, passive components, cable and mobile radios on a canvas and connect them. Built-in templates cover common layouts, and you can save your own designs as templates.
Leaky Feeder Designer
Design and simulate radiating cable networks for mines, tunnels and large buildings on a drag and drop canvas, with multi-carrier signal levels, intermodulation, DC power and uplink budgets.
Included in the 14-day Pro trial on every new account. No credit card.
Walkthrough
See it working
Step 02
Add components
Add base stations, head ends, amplifiers, passive components, test points, donor antennas and mobile radios to the canvas.
Step 03
Connect components with cable
Connect an output to an input to create a cable, then choose the cable from the component catalogue and set its length.
Step 04
Configure each component
Set amplifier gain, noise figure and output limits, optional downlink and uplink passbands, head end settings and the base station carriers.
Step 05
Add mobile radios
Place a mobile radio, set its power, sensitivity, antenna gain, body loss and distance from the cable, and link it over the air to a point on the network.
Step 08
Review the validation messages
Validation flags design problems as you edit, such as unconnected components, unterminated outputs, cables used outside their rated band and amplifier headroom issues.
Step 09
Save your work
The workspace saves automatically in your browser and to your account, and any design can be saved as a template.
Example network with base stations, combiners, a head end and AGC amplifiers.
Overview
What the Leaky Feeder Designer does
Leaky feeder (radiating cable) provides radio coverage in mines, road and rail tunnels and large buildings where antennas cannot reach. The cable leaks signal along its length, but loss builds up over the run, so amplifiers have to be placed and set with care. Each amplifier adds noise and intermodulation, needs DC power fed along the cable, and has to serve both the downlink to the radios and the uplink back to the base station.
Read the full overview
The Leaky Feeder Designer lets you build the network as a schematic. Base stations, head ends, line and AGC amplifiers, attenuators, splitters, couplers, combiners, power inserters, terminations, test points, donor antennas and mobile radios are placed on a canvas and joined with cable. Each component carries its electrical specification, and cable and amplifier data come from the noIM₃ component catalogue.
The simulation runs on every edit. It follows each carrier through the network and reports the power, noise floor and signal to noise ratio at every port, the cascaded noise figure and third order intermodulation at each amplifier, the DC voltage at each powered device, and the uplink and downlink margin for each mobile radio. Validation flags design problems as you work, and the workspace saves in your browser and to your account.
Capabilities 8
Multi-carrier simulation
Every downlink and uplink carrier is tracked through cable loss, splitter and combiner loss, amplifier gain and AGC regulation. Any port shows the composite power, noise floor, signal to noise ratio and each carrier's level.
Cascaded noise figure
Cascaded noise figure is calculated with the Friis formula, with the cable loss between amplifiers included as a stage. This avoids crediting an amplifier with gain that the cable after it has already lost.
Intermodulation with passband filtering
Third order intermodulation products are calculated at each amplifier and head end from the carrier plan and each device's OIP3. Downlink and uplink passbands can be set on a device so that products a duplexer or cavity filter would reject are left out.
DC power feed
The tool follows the DC supply along the cable from each head end or power inserter, using the cable DC resistance and each amplifier's current draw. It shows the voltage at each powered device and flags any that fall below their minimum supply voltage.
Uplink and downlink budgets
Mobile radios link over the air to a point on the network. The uplink budget follows the radio's signal through body loss, the distance falloff to the cable and the cable coupling loss, then back through the amplifiers to the base station receiver, and a summary shows which direction limits each radio.
Off-air repeater checks
For a head end fed off air from a donor site, the tool calculates the donor signal level and the isolation margin between the network gain and the donor antenna. Designs where the gain approaches the isolation are flagged as at risk of oscillation.
Validation and saving
Live validation flags unconnected components, unterminated outputs, cables used outside their rated band, radio and carrier mismatches and amplifier headroom problems. Designs save automatically in your browser and to your account.
Inputs and outputs
What goes in, what comes out
Inputs 9
- Network components placed and connected on the canvas
- Radiating and feeder cable from the component catalogue, with lengths
- Amplifier and AGC amplifier settings, including optional passbands
- Head end and base station carriers with downlink and uplink frequencies
- Splitter, coupler, combiner, attenuator and tap losses
- Power inserters and DC blocks for the DC feed
- Mobile radio power, sensitivity, antenna gain, body loss and distance from the cable
- Donor antenna details for off-air repeater designs
- Global settings for temperature derating, design margin and the noise environment
Outputs 10
- Composite and per-carrier power at every port
- Noise floor and signal to noise ratio at every port
- Cascaded noise figure and network summary
- Intermodulation products and headroom at each amplifier
- DC voltage and current at each powered device
- Uplink and downlink budget for each mobile radio
- Two-way link summary with the limiting direction
- Donor signal level and isolation margin for off-air designs
- Propagation delay through the network for digital systems
- Validation messages
Standards & methodology
- Friis formula for cascaded noise figure, with inter-stage cable loss
- ITU-R SM.1134 intermodulation product levels
- Manufacturer datasheet longitudinal loss and coupling loss for radiating cable
- Coupling loss distance falloff of 20 log₁₀ from the datasheet reference distance for the 95 per cent figure (Eupen radiating cable application note)
Use cases
When to use this tool
- 01Designing leaky feeder networks for underground mines
- 02Designing radiating cable coverage for road and rail tunnels
- 03Planning in-building radiating cable systems for large sites
- 04Checking amplifier headroom and intermodulation for a multi-carrier plan
- 05Checking that remote DC power reaches every amplifier
- 06Confirming uplink and downlink margins for handheld and vehicle radios
- 07Checking an off-air repeater design for donor level and isolation
- 08Training engineers in radiating cable system design
What is leaky feeder and where is it used?
Leaky feeder, or radiating cable, is coaxial cable with slots that let signal leak out along its length, so it works as a long antenna. It is used in underground mines, road and rail tunnels and large buildings where normal antennas cannot give continuous coverage. The trade-off is that loss builds up along the cable, so long runs need amplifiers.
What does the simulation calculate?
It follows every carrier through the network, including cable loss, component losses, amplifier gain and AGC regulation. It calculates the noise floor and signal to noise ratio at each port, cascaded noise figure with the Friis formula, third order intermodulation at each amplifier and head end, the DC power feed and the uplink and downlink budgets for each mobile radio.
How are mobile radios modelled?
A mobile radio connects over the air to a point on the network rather than by cable. The uplink budget takes the radio's transmit power, antenna gain and body loss, the distance falloff to the cable and the cable's coupling loss, then follows the signal back through the amplifiers to the base station receiver. The radio must be on one of the network's carriers and use the same radio system.
How does passband filtering affect intermodulation?
Amplifiers and head ends can be given downlink and uplink passbands. When passbands are set, intermodulation products that fall outside them are left out, as a duplexer or cavity filter would remove them. The reported worst case then reflects only the products that would pass through the device.
Where do the cable and amplifier data come from?
Radiating cables, feeder cables and leaky feeder amplifiers load from the noIM₃ component catalogue, which is built from manufacturer datasheets, alongside a set of generic amplifier presets. Cable loss is fitted to the datasheet curve so it can be read at each carrier frequency. If the catalogue cannot be reached, the tool falls back to a built-in cable set and says so.
Is my design saved?
Yes. The workspace, including all open design tabs, saves automatically in your browser and to your account, so it is available when you return. You can also save a design as a template to reuse later.
Does the tool certify a design?
No. The simulation and validation messages support design decisions, but they do not certify a design or replace site measurement, site approvals or licensing. Results depend on the component data and settings you enter.
Related
Related tools
-
3D Leaky Feeder CoverageLeaky Feeder Design -
Amplifier Spacing CalculatorLeaky Feeder Design -
LCX Cable SelectorLeaky Feeder Design -
Intermodulation CalculatorFrequency Coordination
Further reading
- FDMA vs TDMA Underground: Why Amplifier Group Delay Favours FDMA on Leaky Feeder and DAS Cascades FDMA has margin where TDMA has a budget. Slot timing, delay tolerance and amplifier group delay on leaky feeder and DAS cascades, with the standards' numbers.
- Designing Leaky Feeder Coverage for Underground Mines A working guide to leaky feeder design underground: the two loss numbers behind every layout, amplifier spacing, uplink and downlink budgets, and mine geometry.
Free for 14 days
Included in the 14-day Pro trial on every new account. No credit card.