RU2723983C1 - Frequency meter of microwave signals on delay lines with negative time of group delay - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to measurement equipment and can be used for rapid measurement of frequency of continuous microwave signals in a wide frequency range. Invention is a wideband microwave signal frequency meter consisting of series-connected input amplifier-limiter, band-pass microwave filter, in-phase microwave power divider, N delay lines, N phase correlators, which outputs are connected to a computing device, wherein the meter additionally includes N delay lines with negative group delay time, wherein inputs of delay lines with negative group delay time are connected to outputs of in-phase divider of microwave power, and outputs of delay lines with negative group delay time are connected to inputs of corresponding phase correlators.

EFFECT: technical result is reduction of frequency measurement error.

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Description

A device for measuring the frequency of microwave signals [1]. The microwave frequency meter consists of an input broadband amplifier, a set of delay lines, phase correlators, analog-to-digital converters, a computing device, and a control device.

The disadvantage of this device is the cumbersomeness caused by the need to use several delay lines, the minimum and maximum delay time of which to achieve a given accuracy and range of operating frequencies must differ several times. Another disadvantage of this device is the low sensitivity of the device, limited by linear losses in long delay lines.

The closest in technical essence and the achieved technical result to the claimed invention is a device for measuring the frequency of microwave signals [2]. The microwave signal frequency meter consists of an input broadband limiter amplifier, an input microwave passband filter, a set of delay lines, phase correlators, and a computing device.

The disadvantage of this device is the cumbersomeness caused by the need to use several delay lines, the minimum and maximum delay times of which, in order to achieve a given accuracy and range of operating frequencies, must differ several times. Another disadvantage of this device is the low sensitivity of the device, limited by linear losses in long delay lines.

The technical result of the invention is to reduce the overall dimensions and mass, to reduce the error in measuring the frequency.

The aim of the invention is to reduce the bulkiness of the device and to reduce the error of frequency measurement due to the use of delay lines with negative group delay time.

The claimed result is achieved by the fact that in the device consisting of a series-connected input amplifier-limiter, a pass-band microwave filter, an in-phase microwave power divider, N delay lines, N phase correlators, the outputs of which are connected to a computing device, N delay lines with a negative group delay time, while the inputs of the delay lines with a negative group delay time are connected to the outputs of the in-phase microwave power divider, and the outputs of the delay lines with a negative group delay time are connected to the inputs of the corresponding phase correlators.

The invention is illustrated by the drawing in figure 1. Figure 1 shows a structural diagram of a frequency meter of microwave signals with delay lines with a negative group delay time. The frequency meter of microwave signals contains: input amplifier-limiter 1, bandpass microwave filter 2, microwave power divider 3, delay lines 4.1 ... 4.N, delay lines 5.1 ... 5.N with negative group delay time, phase correlators 6.1 ... 6 .N computing device 7.

Figure 2 presents the discriminatory characteristics of phase correlators.

For convenience, we consider the operation of a broadband frequency meter, the functional diagram of which is shown in Figure 1. A broadband microwave frequency meter operates as follows. The input microwave signal with a frequency of ω _{0 is} fed through an amplifier-limiter 1 to a band-pass filter 2, limiting the input frequency band. Next, the signal is fed to the in-phase microwave power divider 3, where the input signal is divided into N equal parts. The number of delay lines 4.1 ... 4.N, delay lines 5.1 ... 5.NN with negative group delay time, phase correlators 6.1 ... 6.N is determined by the operating band of the device and the required frequency measurement accuracy. Suppose that the delay lines 4.1,4.2, ..., 4.N have a delay time equal to τ _1P , τ _1P , .. τ _NP . Suppose also that delay lines 5.1,5.2, ..., 5.N with a negative group delay time have a delay time of −τ _1M , -τ _2M , ..- τ _NM . The phase incursions acquired by the signals at the outputs of the delay lines 4.1,4.2, ..., 4.N will be: θ ₁ = ω ₀ τ _1P , θ ₂ = ω ₀ τ _2P , ..., θ _n = ω ₀ τ _NP . At the same time, phase raids acquired by the signals at the outputs of the delay lines 5.1,5.2, ..., 5.N with a negative group delay time will be: ϕ ₁ = −ω ₀ τ _1M , ϕ ₂ = −ω ₀ τ _2M , ..., ϕ _n = −ω ₀ τ _NM . The signals from the output of the delay lines 4.1,4.2 ... 4.N and the delay lines 5.1,5.2, ..., 5.N with a negative group delay time are fed to the inputs of the phase correlators 6.1,6.2, ..., 6.N. Phase correlators 6.1,6.2, ..., 6.N form the following discriminatory characteristics, the appearance of which is shown in figure 2 (DFM ₁ - 1, DFM ₂ - 2, ..., DFM _n - 3):

(1) $$\mathrm{<figure-callout\; id="1"\; label="D\; F\; M"\; filenames="00000005.png,00000006.png"\; state="\{\{state\}\}">D\; </figure-callout>}F{M}_{}{}_1=A_1(1+\cos \omega ({\tau }_{1P}+{\tau }_{1M}))$$

(1)

(2) $$DF{\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="00000005.png,00000006.png"\; state="\{\{state\}\}">M</figure-callout>}}_2=A_2(1+\cos \omega ({\tau }_{2P}+{\tau }_{2M}))$$

(2)

(3) $$DF{\mathrm{<figure-callout\; id="3"\; label="M"\; filenames="00000005.png,00000006.png"\; state="\{\{state\}\}">M</figure-callout>}}_3=A_3(1+\cos \omega ({\tau }_{3P}+{\tau }_{3M}))$$

(3)

where A ₁ , A ₂ , ..., A _n are the proportionality coefficients;

τ _1P , τ _2P , ... τ _NP is the delay time of delay lines 4.1,4.2 ... 4.N;

τ _1M , τ _2M , ... τ _NM - delay time of delay lines 5.1,5.2 ... 5.N with negative group delay time;

ω is the circular frequency.

The correlator 6.1 has an unambiguous but relatively flat correlation characteristic in the operating frequency range (2-3 GHz, Fig. 2), for this reason the correlator 6.1 serves for a rough estimate of the frequency of the input signal. At the same time, phase correlators 6.2, ..., 6.N have ambiguous correlation functions, the steepness of which is higher than the steepness of the correlation characteristic of the correlator 6.1. Correlators 6.2,6.3, ... 6.N are used to improve the accuracy of measuring the frequency of the input signal. The computing device 7 is designed to determine the frequency of the input signal from the voltages from the phase correlators 6.1,6.2, ..., 6.N.

It can be seen from expressions 1–3 that introducing delay lines with a negative group delay time in front of phase correlators increases the argument of the cos function, which is equivalent to increasing the length (delay time) of the delay lines 4.1,4.2, ..., 4.N. Thus, the length of the lines 4.1,4.2, ..., 4.N delay and the overall dimensions of the device can be reduced. Delay lines 5.1,5.2, ..., 5.N with negative group delay time can be implemented on passive [3] and active elements [4,5].

List of sources used

1. Schmidt, R.O. Simultaneous signals IFM receiver using plural delay line correlators. U.S. Patent No. 5,440,228.

2. Tsui, J.B.Y., Hedge, J.N. Instantaneous frequency measurement (IFM) receiver with two signals capability. U.S. Patent No. 5,291,125.

3. Chaudhary, G. A design of compact wideband negative group delay network using cross coupling / G. Chaudhary, Y. Jeong // Microwave and optical technology letters. - 2014. - No. 11. - VOL56. - pp. 2495 - 2497.

4. Wu, C.-T.M. A Dual-Purpose Reconfigurable Negative Group Delay Circuit Based on Distributed Amplifiers / C.-T. M. Wu, S. Gharavi, B. Daneshrad, T. Itoh // IEEE Microwave and wireless components letters. - 2013. - pp. 13.

5. Ravelo, B. Investigation on Microwave Negative Group Delay Circuit / B. Ravelo // Electromagnetics. - 2011. - No. 31. - pp. 537 - 549.

Claims (1)

A broadband microwave signal frequency meter, consisting of a series-connected input amplifier-limiter, a band-pass microwave filter, an in-phase microwave power divider, N delay lines, N phase correlators, the outputs of which are connected to a computing device, characterized in that N delay lines with a negative group delay time, while the inputs of the delay lines with a negative group delay time are connected to the outputs of the in-phase microwave power divider, and the outputs of the delay lines with a negative group delay time are connected to the inputs of the corresponding phase correlators.

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