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Ladder line is an older, simpler form of parallel-wire line, often called open wire line. The configuration looks like a rope ladder , hence the name. It can either be purchased already made by a cable company, or home-made ; the construction is easy, though tedious, and originally all radio amateurs made their own open wire line.
With no matching unit, Varney specified 75 Ω cable be used at the junction of the ladder line and coax (not 50 Ω); the higher 75 Ω impedance makes a closer match the end of the ladder line. An earth-grounded 4:1 voltage balun may be used to connect the coax to the ladder line, and 1:1 current balun should be used between the coax and the ...
For example, transformation of 300-Ω twin-lead or 450-Ω ladder line (balanced) to 75-Ω coaxial cable (unbalanced), or to directly connect a balanced antenna to unbalanced coaxial cable. To avoid feed line radiation, baluns are typically used as a form of common mode choke attached at the antenna feed point to prevent the coaxial cable from ...
The most widely used types of feed line are coaxial cable, twin-lead, ladder line, and at microwave frequencies, waveguide. Particularly with a transmitting antenna, the feed line is a critical component that must be adjusted to work correctly with the antenna and transmitter. Each type of transmission line has a specific characteristic impedance.
The simplest example this method is the quarter-wave impedance transformer formed by a section of mismatched transmission line. If a quarter-wavelength of 75 Ohm coaxial cable is linked to a 50 Ohm load, the SWR in the 75 Ohm quarter wavelength of line can be calculated as 75Ω / 50Ω = 1.5; the quarter-wavelength of line transforms the ...
To match the impedances, both cables must be connected to a matching transformer with a turns ratio of 2:1. In this example, the 300-ohm line is connected to the transformer side with more turns; the 75-ohm cable is connected to the transformer side with fewer turns. The formula for calculating the transformer turns ratio for this example is:
Examples include 75-ohm resistors often used to terminate 75-ohm video transmission coaxial cables. Types of transmission line cables include balanced line such as ladder line , and twisted pairs ( Cat-6 Ethernet , Parallel SCSI , ADSL , Landline Phone , XLR audio , USB , Firewire , Serial ); and unbalanced lines such as coaxial cable (Radio ...
A resistor ladder is an electrical circuit made from repeating units of resistors, in specific configurations. An R–2R ladder configuration is a simple and inexpensive way to perform digital-to-analog conversion (DAC), using repetitive arrangements of precise resistor networks in a ladder -like configuration.