Category: Transmission Lines

Choke Balun

Choke Balun: A Choke Balun, or balance-to-unbalance transformer, is a circuit element used to connect a balanced line to an unbalanced line or antenna. Or, as is perhaps a little more common, it is used to connect an unbalanced (coaxial) line to a balanced antenna such as a dipole. At frequencies low enough for this […]

Two Hole Directional Coupler

Two Hole Directional Coupler: It is often necessary to measure the power being delivered to load or an antenna through a transmission line. This is often done by a sampling technique, in which a known fraction of the power is measured, so that the total maybe calculated. It is imperative, under these conditions, that only […]

Double Stub Matching

Double Stub Matching: If a transmission-line matching device is to be useful in a range of different matching situations, it must have as many variable parameters, or degrees of freedom, as the standing-wave pattern. Since the pattern has two degrees of freedom (the SWR and the position of the first maximum), so must the Double […]

Smith Chart for Transmission Line

Smith Chart for Transmission Line: The various properties of transmission lines may be represented graphically on any of a large number of charts. The most useful representations are those that give the impedance relations along a lossless line for different load conditions. The most widely used calculator of this type is the Smith Chart for […]

Reactance Properties of Transmission Lines

Reactance Properties of Transmission Lines: Reactance Properties of Transmission Lines : Just as a suitable piece of transmission line may be used as a transformer, so other chosen transmission-line configurations may be used as series or shunt inductive or capacitive reactances. This is very advantageous indeed. Not only can such circuits be employed at the […]

Quarter Wavelength Transmission Line

Quarter Wavelength Transmission Line: Sections of transmission lines that are exactly a Quarter Wavelength Transmission Line or Half Wavelength Transmission Line long have important impedance-transforming properties, and are often used for this purpose at radio frequencies. Impedance inversion by Quarter Wavelength lines: Consider Figure 7-8, which shows a load of impedance ZL connected to a […]

Standing Waves in Transmission Lines

Standing Waves in Transmission Lines: Standing Waves in Transmission Lines : When power is applied to a transmission line by a generator, a voltage and a current appear whose values depend on the characteristic impedance and the applied power. The voltage and current waves travel to the load at a speed slightly less than νc, […]

Losses in Transmission Lines

Losses in Transmission Lines: Types of Losses in Transmission Lines are three ways in which energy, applied to a transmission line, may become dissipated before reaching the load: radiation, conductor heating and dielectric heating. Radiation losses occur because a transmission line may act as an antenna if the separation of the conductors is an appreciable […]

Fundamentals of Transmission Lines

Fundamentals of Transmission Lines: Fundamentals of Transmission Lines (in the context of this book) are considered to be impedance-matching circuits designed to deliver power (RF) from the transmitter to the antenna, and maximum signal from the antenna to the receiver. From such a broad definition, any system of wires can be considered as forming one or […]