Transmission Line Directional Coupler Research Articles

A Proposal for a High-Voltage Transmission Line Directional Coupler

Directional couplers are devices generally used in high-frequency transmission lines and waveguides that respond to forward and reverse traveling waves separately. Hence they can be used to either measure standing-wave ratio in the steady state or to determine the direction of a propagating transient wave. Here, a design is proposed for a directional coupler to be used on multimode high-voltage transmission lines. Its performance is analyzed and several suggestions are made to improve its design.

Transmission-line directional couplers for impedance transforming

Normalized scattering parameters of a two-port circuit terminated in arbitrary impedances are derived and design equations of directional couplers for impedance transforming are derived. To verify the design equations, a microstrip directional coupler is designed at a center frequency of 2GHz, fabricated on a substrate (/spl epsiv//sub r/=3.5,H= 30mil, tan/spl delta/= 0.04) and measured. The measured performance shows good agreement with the simulated one.

Transmission line directional couplers with a generalised sinusoidal coupling coefficient

A generalised asymmetrical tapered sinusoidal coupling coefficient theory is presented. Using the first order approximation equations, the new theory exhibits good electrical coupling performance with reasonable coupler size.

Power Combiners/Dividers for Loop Pickup and Kicker Arrays for FNAL Stochastic Cooling Rings

The anti-proton accumulator and debuncher at FNAL will use stochastic methods to ''cool'' the beam. Pairs of quarter-wavelength directional-coupler loops are used to detect and kick the beam. The loops are copper plates which are flush with the upper and lower wall of a rectangular beam pipe. The plates, when surrounded by a properly sized pocket, form a 100-ohm transmission-line directional coupler. As the beam passes, a signal which gives position and time information, is induced in the plates. But, because the signal levels are low (<.5 picowatts per pair), a power combiner (usually several primary combiners feeding a secondary combiner) is used to combine the outputs of many loops. Subsequently, the combined signal is amplified, filtered and then fed into a divider, (that is, a combiner operating in reverse). The divider distributes the signal into a different set of loops which modify (kick) the beam's position. Since the loop couplers are arranged linearly, in arrays of various lengths, combiners also provide a convenient method of reducing the number of vacuum feedthroughs and preamplifiers and their related costs in performance and dollars. In this note we describe various stripline combiner systems that add the outputs of 4, 8, 16 ormore » 32 loops.« less

A uniformly coupled asymmetric TEM-mode transmission-line directional coupler

An analysis of an asymmetric coupled four-port transmission-line coupler in terms of a two-port transmission line corresponding to two normal modes is presented. This method permits the use of a transmission matrix approach which simplifies considerably the derivation of an expression for coupling and also establishes the mathematical equivalence of such couplers to transmission-line stepped impedance filters. The coupling as well as the terminating impedances required for an impedance match and infinite directivity have been determined in terms of self and mutual immittance parameters, expressions for which have been determined as explicit functions of the line parameters. The method of design of a coupler for specified values of coupling and terminating impedances is also presented.

Tables for Asymmetric Chebyshev High-Pass TEM-Mode Directional Couplers

Tables are presented for the design of asymmetric nonuniform-coupled transmission-line directional couplers, having a high-pass Chebyshev equal-ripple coupling response. The coefficients of the continuously tapered coupling factor represented as a polynomial of sixth order are tabulated for mean couplings of -3, -6, -8.34, -10, and -20 dB and for a given ripple of the high-pass coupling response.

A Note on Transmission-Line Directional Coupler

A Note on Transmission-Line Directional Coupler

On High-Pass Transmission-Line Directional Couplers (Correspondence)

On High-Pass Transmission-Line Directional Couplers (Correspondence)

Coupled linearly tapered transmission line directional coupler†

A coupled linearly tapered transmission line directional coupler has been analysed and an asymmetrical directional coupler is shown to possess high pass characteristics.

Directional Couplers with Hyperbolic Variation of Coupling Coefficient

Symmetrical and asymmetrical directional couplers employing hyperbolic variation of coupling coefficients have been studied and their results compared with coupled uniform transmission line directional couplers.

High-Pass Transmission-Line Directional Coupler (Correspondence)

High-Pass Transmission-Line Directional Coupler (Correspondence)

Directional Couplers with Exponential Variation of Coupling Coefficients

Asymmetrical and symmetrical form of strip line directional couplers having exponentially tapered coupling coefficient have been developed so that operation over a broad bandwidth is possible. The expression for the coupling of such directional couplers have been derived and the characteristics of these directional couplers are compared with the corresponding stepped transmission line directional couplers.

An Equivalence Principle for Nonuniform Transmission-Line Directional Couplers

The analysis of transmission-line directional couplers is formulated in terms of a pair of first-order matrix differential equations. It is shown that for every nonuniform directional coupler that is electrically symmetric, there exists an equivalent pair of dual nonuniform transmission lines. It is also shown that a matched, transmission-line directional coupler having an absolutely continuous characteristic impedance matrix must be symmetric. Restrictions on the terminating impedances and the implications of these restrictions on the realizability of transmission-line couplers are investigated. Finally, the tapered-line magic T is treated as an example.

Coupled Nonuniform Transmission Line and Its Applications

Theory and applications of coupled nonuniform transmission lines are described. Matrix representations of a general coupled nonuniform transmission line are presented, by means of which the behavior of any coupled nonuniform transmission line maybe completely described. Among a wide variety of applications of coupled nonuniform transmission lines, two typical networks, one the coupled nonuniform transmission-line folded all-pass network and the other the coupled nonuniform transmission-line directional coupler, are treated in detail. Equivalent circuit representatious of these two networks are presented, which enable the designer to synthesize them in a greatly simplified manner by making use of the theories now available for more conventional single nonuniform transmission lines. In addition, the properties of these two networks using coupled exponential line are investigated. Design procedure is also given for asymmetrical coupled exponential-line directional couplers having excellent characteristics.

A self-compensating lumped element broadband HF directional coupler

A novel design criterion for the lumped element coaxial transmission line directional coupler is discussed for HF band operation (2 to 30 MHz). This technique utilizes the inherent self-compensating low-pass equalizing characteristic of a high reactance secondary transformer winding. Experimental results of a representative coupler design are shown.

Transmission-line directional couplers for very broad-band operation

The development of coupled-transmission-line theory and applications has extended the bandwidth of certain microwave components to one decade or more. A review of the theory is presented in the most simple general form, which enables the effects of tolerances and perturbations to be calculated. A survey of available coupled-line configurations is presented, including a new printed re-entrant type, with, in some instances, more accurate formulas than those available in the literature. The theoretical aspects of this work are substantially complete, but there are practical difficulties associated with obtaining good directivity and higher-frequency devices.

Further Analysis of Transmission-Line Directional Couplers

The conditions of infinite directivity for transmissionline directional couplers are derived in a general and rigorous way. Exact expressions valid for any degree of coupling are found. The case of small coupling and the case of a matched primary line are considered as particular cases of this general analysis. In the case of small coupling, the condition Z11Z44 = 1 and Z22Z33 = 1 given by W. L. Firestone in a recent paper are found to be correct; it is shown also that these simple conditions do not apply anymore when the coupling becomes large.

Analysis of Transmission Line Directional Couplers

Five different types of transmission line systems are analyzed and are shown to possess directional properties at the lower radio frequencies. The conditions of mismatch on either transmission line or on both transmission lines have been taken into account, as well as lengths of coupling greater than a fractional wavelength. A new and more general scatter matrix for directional couplers which includes the condition of mismatch is developed. In addition, lumped circuit directional couplers have been developed as a consequence of the general transmission line theory.

Über die Behandlung von Mehrleitersystemen mit transversal elektromagnetischen Wellen bei hohen Frequenzen

The paper deals with problems of wave-propagation on multiconductor transmission lines at very high frequencies. The transmission line equations for current and voltage on each conductor are given in a generalized form using matrix symbols. Two examples show how these equations are to be applied to practical problems and how proper boundary conditions are to be introduced. The first example concerns the theory of a transmission line directional coupler, the second example a simplified theory of the folded dipole antenna.