Search results
Results from the WOW.Com Content Network
500–600 Ω open wire line or ladder line feeding a high wire antenna. The "ladder rung" spacers can be made out of any convenient insulating material – at present, usually short pieces cut from plastic plumbing pipe – formerly either long, thin ceramic insulators or dowel stubs of water-proofed wood were used.
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 ...
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 category of simple antennas consists of dipoles, monopoles, and loop antennas. Nearly all can be made with a single segment of wire (ignoring the break made in the wire for the feedline connection). [citation needed] Dipoles and monopoles called linear antennas (or straight wire antennas) since their radiating parts lie along a single ...
At shortwave frequencies, a dipole cut for the longest used wavelength, fed with ladder line and matched with an antenna tuner, would make better use of the applied power than the T²FD. [7] Many ready-made commercial versions of the T²FD are available for the professional, military, amateur radio, and hobby listening markets. [6] [7] [8]
A type of transmission line called a cage line, used for high power, low frequency applications. It functions similarly to a large coaxial cable. This example is the antenna feed line for a longwave radio transmitter in Poland, which operates at a frequency of 225 kHz and a power of 1200 kW.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
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 ...