Ad
related to: ladder line j pole calculator
Search results
Results from the WOW.Com Content Network
The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
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 ...
The top-to-top half-wave connecting wire serves as a phasing line that keeps radiation from the two antennas in-phase; even if the system feedpoint is connected elsewhere. Since a quarter-wave monopole's current is highest nearest its feedpoint, the nominal top-feed puts the maximum radiating current up high, at the top of each monopole.
Types of transmission line include parallel line (ladder line, twisted pair), coaxial cable, and planar transmission lines such as stripline and microstrip. [5] [6] The higher the frequency of electromagnetic waves moving through a given cable or medium, the shorter the wavelength of the waves. Transmission lines become necessary when the ...
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!
The folded unipole antenna was first devised for broadcast use by John H. Mullaney, an American radio broadcast pioneer, and consulting engineer. [2] It was designed to solve some difficult problems with existing medium wave (MW), frequency modulation (FM), and amplitude modulation (AM) broadcast antenna installations.
So Z 1 can be realized as an R-C ladder network, in the Cauer manner, [21] and is shown as part of the bridged-T circuit below. Z 2 is the dual of Z 1 , and so is an R-L circuit, as shown. The equivalent lattice circuit is shown on the right–hand side.
Ad
related to: ladder line j pole calculator