Power attenuator

FIELD: radio engineering, communication.

SUBSTANCE: power attenuator comprises N series-connected matched links on identical substrates mounted with equal spacing on a heat-conducting base; each subsequent link, for the same power losses therein, has higher attenuation than the previous link and the power transfer coefficient of the links (K_P<1) is a function of at least two parameters, e.g. K_PM=f(N, M,…), where N is the number of links; M is the index number of a link (M=1, 2, 3,…, N). The attenuator has a terminal connected to the output of the corresponding link, which corresponds to the parameters: number of links to said terminal and power transfer coefficient from the input to said terminal.

EFFECT: broader functional capabilities and high reliability.

4 cl, 1 dwg

The invention relates to the field of radio electronics and can be used as a dummy load for testing a powerful transmitting devices.

Known for a strong attenuator [1], which is used as a load containing three agreed, connected in series one behind the other T-shaped element made by the method of thin-film technology from the resistive absorbers on substrates with equal geometrical dimensions, made of the same material, installed on the heat-conducting base with the same step. Along with such advantages as high manufacturability and the possibility of unification, the attenuator has a fundamental flaw: there are no calibrated outputs (with a given gear ratio), since the coefficients of transmission links were selected based on the lowest possible differences in emitted power, and not by necessity. This limits the functionality of the attenuator load, while reducing its reliability due to the lack of being able to turn off the signal source (transmitter) or switch it to standby load when the emergency situation. This resistive absorbers in the attenuator only briefly be subjected to overload and will not fail.

Most BL is skim to the technical essence and the achieved result for the proposed device is a powerful attenuator [2], containing N connected in series to each other concerted links on identical substrates that are installed with the same step on thermally conductive base, each subsequent link which has a greater attenuation than the previous one, and the coefficient of transmission power of each link is given by the expression:

To_RM=(N-M)/(N-M+1),

where M is the sequence number of the link;

N is the number of links.

Despite such positive qualities as increased reliability due to the same heat dissipation in the substrate, the high stability of its electrical parameters, the attenuator has the same drawback: there are no calibrated outputs, since the coefficients of the transmission links are calculated, and are not selected (the selection ratio of at least one link will lead to mismatching of allocated it capacities with the other links). Again, this limits the functionality of the attenuator, while reducing its reliability.

The aim of the present invention is to provide a powerful attenuator load, having at least one calibrated output that will enhance its functionality and reliability. This objective is achieved in that in a powerful attenuator containing N are connected in series one after another of soglasovan is x units on the same substrate, installed with the same step on thermally conductive base, in which each subsequent link with the same power losses in them has a greater attenuation than the previous one, and the ratio of the capacity of links (K_P<1) is a function of at least two parameters, for example:

To_RM=f(N, M,...),

where N is the number of links;

M is the sequence number of the link (M=1, 2, 3,...,N),

entered terminal connected to the output of the corresponding link, which is set in accordance with parameters N_(K)and K_R(K)where N_(K)the number of links to the specified terminals;_R(K)- the ratio of power from the input to the specified terminals, and the ratio of the transmission capacity of the links is described by the function

$$K_{PM}=f\left(N_{(K)},M,K{P}_{(K)}\right)$$,

moreover, the relation$$\frac{N_{(K)}}{1-K_{P(K)}}$$there are a whole number.

In addition to the, the ratio of the power can be specified by a single parameter attenuator:$$K_{PM}=f\left(K_{P(M-1)}\right)$$or$$K_{P(M-1)}=f\left(K_{PM}\right)$$.

The figure 1 shows the structural diagram of the claimed device,

1 - links attenuator;

R_N- coordinated load;

K_P1To_P2To_P3,..., K_PN- transfer coefficients of the power units;

P₁P₂, R₃,..., R_N- power on the outputs of the units;

P_I- input power.

Considering that under the terms of the equality of the heat dissipation of the power loss at all levels should be the same, i.e. ΔP=P_I/N=P_{The SWEAT.}/N_(K)(R_{The SWEAT.}- power loss in the attenuator on the input to the specified terminals), the designated transmission ratios:

$$K_{P1}=P_1/P_{\mathrm{In}X}=\frac{P_{\mathrm{In}X}}{-}{P}_{\mathrm{In}X}=\frac{N_{(K)}-1\cdot \left(1-K_{P(K)}\right)}{N_{(K)}-0\cdot \left(1-K_{P(K)}\right)}$$

$$K_{P2}=P_2/P_1=\frac{P_{\mathrm{In}X}-2\cdot \Delta P}{P_{\mathrm{In}X}-\Delta P}=\frac{N_{(K)}-2\cdot \left(1-K_{P(K)}\right)}{N_{(K)}-1\cdot \left(1-K_{P(K)}\right)}$$

$$K_{P3}=P_3/P_2=\frac{P_{\mathrm{In}X}-3\cdot \Delta P}{P_{\mathrm{In}X}-2\cdot \Delta P}=\frac{N_{(K)}-3\cdot \left(1-K_{P(K)}\right)}{N_{(K)}-2\cdot \left(1-K_{P(K)}\right)}$$

$$K_{P{N}_{(K)}}=P_{N_{(K)}}/P_{N_{(K)}-1}=\frac{P_{\mathrm{In}X}-N_{(K)}\cdot \Delta P}{P_{\mathrm{In}X}-\left(N_{(K)}-1\right)\cdot \Delta P}=\frac{N_{(K)}-N_{(K)}\cdot \left(1-K_{P(K)}\right)}{N_{(K)}-\left(N_{(K)}-1\right)\cdot \left(1-K_{P(K)}\right)}$$

$$K_{PN}=P_N/P_{N-1}=\frac{P_{\mathrm{In}X}-N\cdot \Delta P}{P_{\mathrm{In}X}-\left(N-1\right)\cdot \Delta P}=\frac{N_{(K)}-N\cdot \left(1-K_{P(K)}\right)}{N_{(}}$$

Then in the General formula is represented as

$$K_{PM}=\frac{N_{(K)}-M\cdot \left(1-K_{P(K)}\right)}{N_{(K)}-\left(M-1\right)\cdot \left(1-K_{P(K)}\right)}$$

From the formula for the determination of losses in the links attenuator follows that

$$N=\frac{N_{(K)}\cdot P_{\mathrm{In}X}}{P_{P\mathrm{About}T.}}=\frac{N_{(K)}\cdot P_{\mathrm{the}X}}{P_{\mathrm{In}X}\cdot \left(1-K_{P(K)}\right)}=\frac{N_{(K)}}{1-K_{P(K)}}$$

It is obvious that the expression must always be an integer (this is achieved by the choice of N_(K)for a given K_R(K)), otherwise there is uncertainty in the calculation of the coefficients of transmission links.

The resulting formula is a function of three parameters attenuator:

1. Set the parameter K_R(K);

2. Select the N_(K);

3. Variable parameter M

Express the ratio of the capacity of the link via the ratio of transmission power of the previous link To_RM=f(K_R(M-1)by substitution in the formula Δ defined as a function of the ratio of transmission power of the previous link:

$$K_{P2}=\frac{2\cdot K_{P1}-1}{K_{P1}}$$

maths num="13"> $$K_{P3}=\frac{2\cdot K_{P2}-1}{K_{P2}}$$

$$K_{P4}=\frac{2\cdot K_{P3}-1}{K_{P3}}$$

$$K_{P{N}_{(K)}}=\frac{2\cdot K_{P\left(N_{{(K)}^{-1}}\right)}-1}{K_{P\left(N_{{(K)}^{-1}}\right)}}$$

$$K_{PN}=\frac{2\cdot K{P}_{(N-1)}-1}{K_{P(N-1)}}$$

Then in the General formula is represented as

$$K_{PM}=\frac{2\cdot K_{P(M-1)}-1}{K_{P(M-1)}}$$

(M=2, 3, 4,...,N),

where K_RM- the ratio of the capacity of the link;

To_R(M-1)- ratio transmission power of the previous link.

Derived formula is a function of one parameter attenuator and can also be used to calculate, but when M≥2, and the coefficient of transmission of the first link should be defined according to claim 2 of the formula (in this case only the results of calculations by both formulas coincide and will be implemented positive effect). If the transfer ratio is defined as the ratio of input power to output, i.e. the$$K_P^{/}>1$$then$$K_{PM}=1/K_{PM}^{/}$$where

$$K_{PM}^{/}=\frac{1}{2-K_{P(M-1)}^{/}}$$

easily obtained from the last formula. It is also possible to obtain an expression of the form K_R(M-1)=f(K_RM), i.e.,

$$K_{P(M-1)}=\frac{1}{2-K_{PM}}$$

or

$$K_{P(M-1)}=\frac{1}{K_{P(M-1)}^{/}}\left(K_P^{/}>1\right)$$

where

$$K_{P(M-1)}^{/}=\frac{2\cdot K_{PM}^{/}-1}{K_{PM}^{/}}$$

and M=N,...,4, 3, 2.

Function$K_{P(M-1)}=f\left(K_{PM}\right)$is also a function of one parameter attenuator and can be used to calculate the ratio of the capacity of the links starting from the penultimate link in the direction to the entrance, and the coefficient of transmission of the last section is equal to zero according to claim 2 of the formula (in this case only the results of calculations by both formulas coincide and will be implemented positive effect). Options one option is convenient that allow you to quickly determine the coefficients of the transmission capacity of the links in direction to the input and output link with a known transfer coefficient calculated by the formula of claim 2. Meanwhile, all the links will dissipate the same power, and the additional presence of terminals will increase the functionality of the attenuator, while increasing its reliability.

As an example of practical implementation of imagine attenuator with a given power dissipation and K_R(K)=0,5. In this case, the number of links will be an integer for any N_(K)in particular, when N_(K)=4 the number of links is N=8. Then the coefficients of transmission units,calculated either according to the formula 2, or by formula, the function of one parameter will be the following:

To_P1=7/8, K_P2=6/7, K_P3=5/6, K_P4=4/5, K_P5=3/4, K_P6=2/3, K_P7=1/2, K_R8=0

or in dB:

To_P1=-0,58 dB, K_P2=-0,67 dB, K_P3=-0,79 dB, K_P4=-0,97 dB, K_P5=-1,25 dB

To_P6=-1,76 dB, K_P7=-3,01 dB, K_R8- accept minus 30 dB.

Such transfer coefficients of the links must be presented to the attenuator, so if you have the same heat dissipation in the substrate it was after the fourth link calibrated output terminal with the specified value To the_R(K).

The application of this invention will allow, while maintaining all the positive qualities similar devices, such as high reliability and manufacturability, the possibility of unification, high stability of electrical parameters, to extend the functionality of the attenuator with a simultaneous increase its reliability.

Sources of information

1. The cake I.A., Winter V.N., Evdokimov M.A. Powerful film resistors on a substrate of AlN and Al₂About₃for RF attenuators great power.

Proceedings of international scientific-technical conference "Reis-2011".

2. Evdokimov M.A. electric calculation powerful attenuator-load thermal criterion // Equipment radio / JSC oiip". - 2012. - VIP. - P.101-104.

2. The attenuator according to claim 1, characterized in that the specified function has the form

3. The attenuator according to claim 1 or 2, characterized in that starting from the second link gain power links can be given as a function of one parameter, and the specified function has the form

or
,
where

and M=2, 3, 4, ..., N;
To_R(M-1),- ratio transmission power of the previous link.

4. The attenuator according to claim 1 or 2, characterized in that starting from the penultimate link in the direction to the entrance of the ratio of the power units can be given as a function of one parameter, and the specified function has the form:

or

Where

a M=N, ..., 4, 3, 2.