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 […]

Directional Coupler

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 the forward […]

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 […]

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 […]