SU871235A1 - Balanced transformer - Google Patents

Description

(54) SYMMETERING TRANSFORMER

one

The invention relates to balancing transformers that can be used in radio circuits for matching and balancing an unbalanced circuit output to a symmetrical one and vice versa, in the RF and microwave bands.

Balun devices are known which contain an unbinding transmission line, a balun transformer-inverter, and a symmetrical load {. The disadvantages of such transformers are the lack of transposition in the direction of unbalanced input, the simplicity of the device. The presence of connecting conductors between the decoupling line and the balancing transformer-inverter significantly reduces the working frequency range of the transformer.

Broadband symmetric transformers are known that allow impedances to be transformed from a symmetrical input to a balanced output 2. The disadvantages of such transformers are the absence of an unbalanced input, device complexity, and large dimensions.

Symmetrical transformers are known, consisting of a ferrite core, symmetric and asymmetrical windings, in which, in order to ensure a constant transformation ratio when matching low-ohmic outputs with high-resistance electrical circuit inputs, the transformer winding is symmetrical in the form of U-shaped

10 metal tubes placed inside hollow ferrite rods, and asymim €: tricky - in the form of two insulated wires laid inside symmetric winding tubes, the number of turns of which is chosen depending on the required transformation ratio 3. The disadvantages of these transformers are low upper limit frequency and complexity

20 devices.

The closest solution to the technical nature of the invention is a strip transformer (4, containing a dielectric board with

25 located on it by the primary (low-resistance) winding, made in the form of one turn of tape on one side of the board, and the secondary (high-resistance) single-layer winding on the other side. our dielectric board. Width and

thirty

The winding pitch of the windings is made varying in the direction of the high potential output of the transformer. This strip transformer can be used as a symmetrical one. Symmetry can only be obtained relative to the midpoint of the turn of the primary winding, which significantly increases the lower cut-off frequency of the transformer.

The disadvantages of this transformer are the increased value of the cutoff frequency and the absence of isolation between the individual symmetrical outputs of the transformer.

The purpose of the invention is to expand the range of frequencies and ensure isolation between the separate symmetrical outputs of the transformer.

The goal is achieved by the fact that an additional one is introduced, the winding in the form of a single turn of tape identical to the turn of the primary winding, located on a dielectric base symmetrically with respect to the secondary one. windings from its free side. The coil of the additional winding is connected in series and in accordance with the coil of the primary winding, the common point of their connection forms the middle terminal of the balun transformer, which, if necessary, is separated, is grounded through a ballast resistor.

The drawing shows a general view of the transformer without isolation.

The transformer contains dielectric bases 1 separating the primary winding, made in the form of symmetrically arranged flat turns 2 and 3. In the gap between the bases 1, the secondary winding 4 is arranged, made in the form of a single-layer flat helix. Coils 2 and 3 are connected to each other in series and according to. Conducting junction 5 forms the common point of a balun transformer. Conducting junction 5 connects to a common point coil 2 and 3 of the end of the inner last turn of winding 4. The free ends of coils 2 and 3 form symmetrical transformer outputs, and the remaining free end of winding 4 forms a high potential input of the transformer.

If it is necessary to isolate between balanced outputs, a common point of turns 2 and 3 is connected to the grounded end of the inner turn of winding 4 via a ballast resistor (not shown).

The operation of the transformer is based on the principle of electromagnetic induction and the division of traveling waves between the lines formed by each turn of winding 4 and flat turns 2 and 3 of the primary winding, forming a bridge (differential) circuit.

The technical effect of the application of the proposed transformer is to significantly expand the range of operating frequencies and the possibility of providing isolation between the output signals.

Claims (4)

1. A symmetrical transformer containing primary and secondary windings in the form of single-layer flat spirals and a dielectric base, characterized in that, in order to expand the range of operating frequencies, the primary winding is made in the form of two symmetrically arranged flat coils, connected consistently and separated by dielectric bases In the space between which the secondary winding is placed, the connection point of the turns of the primary winding forms the middle terminal. 2. A transformer according to claim 1, characterized in that, in order to ensure isolation between symmetrical outputs, the common point of the turns the primary winding is connected to the grounded end of the inner coil of the secondary winding through a ballast resistor. Information sources, taken into account in the examination 1.Avtorsoke certificate of the USSR 632019, cl. H 01 R 5/10, 1976. 2. USSR author's certificate 601765, cl. H 01 F 19/06, 1975. 3. USSR author's certificate No. 461456, cl. H 01 F 19/04, 1972, 4. USSR author's certificate No. 637883, cl. H 01 F 19/00, 1976.