SWL Antenna Distribution System Copywrite 1997 - Alan R. Klase - All rights reserved.

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    I have developed a methodology for connecting multiple LF/MF/HF  receivers to a single antenna via readily available and inexpensive 75-ohm TV cable.  Custom made baluns and splitters provide impedance matching and prevent interaction between receivers.  The following drawing shows a representative system.  Construction details are given below.      
 4:1 Balun

• Provides matching from random wire antenna to coax.
• Also allows separation of antenna ground from building ground to prevent noise pickup.

 Grounding Block

• Installed at entry point to building to head off lightning.
• Standard CATV device
• Electrical code calls for connection to an 8-foot ground rod.

3-dB Hybrid Splitter

• Divides signal between two outputs and maintains 75-ohm impedance.
• Provides 30dB isolation between outputs.
• Broadband:  30KHz to 30MHz.
• CATV splitters don't work well below 10MHz.

A/B Switch

• In this case, allows comparison of the new antenna to the old "reference" antenna.
• Standard CATV device.

4:1 Balun

• Matches 75-ohm cable to old fashioned A-A-G inputs which are usually 300-400 ohms.
• Same component as above.

Loop Coupler

• Couples 75-ohm coax to receivers with internal loop antennas, e.g. table radios.
  
  
  

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