SELF-OSCILLATING MIXER EHF OF THE MEZA-PLANAR GUNN DIODES

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Votoropin S. D. Joint-Stock Company «Research institute of semiconductor devices» Tomsk, Russia e-mail: votoropin@mail. tomsknet. ru

Abstract-Tbe design simplicity, high sensitivity and low cost of self-oscillating mixer (SOM, autodyne) Gunn diode modules result in their preferable use in widely employed radio devices compared to modules with homodyne circuit designs. These advantages of autodyne modules are particularly appreciated in a millimeter-wave Band and are also implemented in their integral circuit designs [1-5].

I.                                      Introduction

Autodyne gauges of UHF range of wave-lengths (30- 300 GHz) on low-current Gunn diodes have a wide application in various devices [1-7]. Simultaneous use of Gunn diodes in function of the transmitter and the converter with amplification of the useful signal reflected from object allows simplifying a circuit and a design of short-range radar devices. At creation of concrete autodynes elements and devices on their basis as a whole it is required to take into account radio physical aspects of radiation, propagation, reflection and reception of UHF signals.

II.                                     Main Part

In autodyne gauges of UHF range, the resonant system is more expedient for carrying out on a slot-hole transfer line and to apply Gunn diodes with planar electrodes [8]. For increase of a connecting factor the design of a Gunn diodes crystal has the form of a square, and cathodes and anode contacts are located on the different sides from the crystal center symmetrically relatively its diagonals. Anode contact has in section the form of the isosceles triangle inverted by the basis to the crystal center, thus the relation of the areas of anodes contact Sa to the area of cathodes contact Sk satisfies to a condition: Sa/Sk > 20-50. Distance L on a diagonal from anodic contact up to cathodes is equal L = КгОпЕг, where Dn is a thickness of an active layer of a diode crystal, Fr is a working frequency of the diode, Кг= 1/(0,7-2,4) GHz at dimension of Dp and L in microns, and F,- in GHz. The similar design, due to reduction of reactive parameters and to increase of connection factor of Gunn diodes has allowed to provide a direct generation of UHF radiation on frequencies up to 70 GHz.

Fig. 1.1- cathodes contact, Sfc 2 – anodes contact, Sa 3 – substrate GaAs

This paper presents the design description and the results of studying a microstrip receiving-transmitting FM module intended for application in autodyne systems with a wavelength of 8 mm.

The module Tigel-8 is built on a polycore base 24x10x0.5 mm, it is designed as a waveguide flange measuring 24x10x10 nun (the waveguide has dimensions 7.2×3.4 mm) and joins waveguides with a square cross-section or a round one. There are tuning screws in the module for the desired frequency tuning and autodyne sensitivity adjustment of the oscillator. The autodyne oscillator resonance system is a half-wave slot resonator with embedded Gunn diode crystals having planar anode and cathode terminals [3-5] and a gallium arsenide varicap 3A631.

The module output power reaches 2 mW, the power potential is as a rule not less than 60 dB when the sig- nal-to-noise ratio is 2 (the typical values are 80-90 dB). The working frequency range 33,4 -36 GHz is overlapped by 3 sub-ranges. The Gunn diode supply voltage can lie between the limits 2.5-4.5 V, the consumed current can be up to 120 mA. The electric frequency change band reaches 1.0 GHz when the control voltage across the varicap changes up to 15 V. Besides the output power change over the whole range of frequency modulation does not exceed 2 dB, and the power potential change is not more than 5 dB. The terminals of the module active elements are completely insulated from the case and this facilitates optimization of the circuits for parametric control and low emitting an autodyne system sianal [5-71.

Fig. 2. The module Tigel-8 (topology):

1 – diode Gunn; 2 – varicap; 3 – resonator; 4 – isolation of the d. c.; 5, 6- circuitry power supply and output.

The study of a climatic effect on the experimental

16   of modules showed that they maintain the above- mentioned performance (data) in the temperature range from – 45°to + 70°C when the relative humidity of the atmosphere is 98 % (at the temperature of 25 C) and they also withstand the exposure to the following mechanical actions 1000 solitary impacts with an acceleration 40 g and vibration in the range of 20-2000 Hz with an acceleration 15 g.

Due to the radiation frequency electric change (at a comparatively low level of spurious amplitude modulation) the developed module provides wider functional facilities or improvement of performance (data) of different radio system in comparison with the systems without modulation [1], which lets them enjoy broad application in radar sensors and meters on transport and in industry, in protecting and monitoring systems in systems of communication and control.

Due to wireless, proximity and high quality of different measurement performance radar sensors take wide application at the monitoring of technological processes, spectroscopy, metrology, robototechnic and R&D, transport.

Usage of low mm-wave and autodyne sensors for creation diagnostic complexes allows to increase accuracy, to decrease transmit- time of measurement, to provide application of digital devices for control equipment systems which has as unmobile as mobile and rotative details. It is in principle impossible by using other sensors, without contact with object. Low level of using UHF power provides ecological clearance of devices.

Autodyne sensor is transmitter- receiver. Parameters of this system is changed by reflected from object signal. Systems, made according autodyne principle, have more simple construction of transmitting – receiving microwave module, which include oscillator based on Gunn diode. It provides simultaneously performance functions of transmitter and converter of reflected from object desired signal. Multifunctional using of Gunn diodes allows significantly to simplify construction of devices. Registration of autodyne signal is carried out in power supply circuit of oscillator. Different regimes of UHF signal transmission and corresponding treatment of autodyne signal allow to get information about sizes, quality of surface, volume electro- physical features of object, parameters of movement (distance, speed and etc.). Application of microwave sensors based on Gunn diodes and subsystems, created on their base has perspectives for systems of production monitoring.

Fig. 3. Sensor 5 mm range M-55314-(1-3) tias dimensions of 15x15x6 mm, weightiess then 3.5 grams (бш2.000.138 ТУ)

III.                                    Conclusion

On the base of desired and producing autodyne sensors the following apparatus may be desired:

1.          For auto industry: radar systems for preventing accidents; speed measure enters; systems of non- slipping; systems for breaking monitoring; guarding systems.

2.          Monitoring Systems: distance measure meter; consumer and industry guarding systems; medical Equipment; non- contact tachometer; tomography.

In the machine industry applying of digital tachometers allows to create a new generation of products for the commercial and industry markets.

Industrial Tomography Systems give an opportunity for monitoring the processing in a real time scale. It is really very good for such systems because of dimension and possibility not to contact the object while investigation.

Table 1. Base Electrical Characteristics:

Parameter

scale

Tigel-8

M55314

Frequency

GHz

33.4-36

55-63

Bias, no less

dB

63

63

Power output

mkW

30-2000

30-600

Supply voltage

V

3-4.5

2.0-3.5

Current, no more

mA

120

60

IV.                                    References

[1]  Buzykin V. Т., Noskov V. Ya. Autodynes. Application fields and development prospects. /Collected volume of scientific works. Radio systems of millimeters and sub-millimeters wave-lengths. – Harkov: the Ukraine Academy of Sciences Radio-physics and Electronics Institute, 1991. P. 38-47.

[2]  Noskov V. Ya., Vesnin V. A., Votoropin S. D., Krasilnikov Y. L. Autodyne microwave sensors for non-contact measuring and monitoring./Materials of the 2nd Cremia conference «Microwave engineering and satellite reception» Sevastopol.-1992.-P. p. 159-164.

[3]  Votoropin S. D. and Noskov V. Ya. Aniysis of operating regimes of EHF hybrid-integrated autodynes based on the Gunn micro power mesa planar diodes. Russian Physics Journal, Vol. 45, No. 2, 2002.

[4]  Buzykin V. Т., Votoropin S. D., Noskov V. Ya. Low-noise microwave oscillators. Development condition and application prospects in metrology. Theses of a report.- Irkutsk, 1991, 44-49.

[5]  Votoropin S. D., Noskov V. Ya. Electronic engineering. Ser. Microwave engineering. 1993. 4(458). C. 70-72.

[6]  Votoropin S. D., Yurchakov V. P. Application of Autodyne EHF-Dand Sensor for Transport Electronics// lEEE-RUSSIA Conference: MIA-ME-1999. – Novosibirsk. – oktober 1999. – P. III.55-III-56.

[7]  Votoropin S. D. and Noskov V. Ya. General model and basic equations for an EHF autodyne HMC based on the Gunn planar mesas. Russian Physics Journal, Vol. 44, No. 12, 2001.

[8]  Votoropin S. D., Yurchenko V. I., Kozhemyakin A. M. Gann Diole. Patent RF № 2064718, MPK HOI L 47/00, 47/02, publ. В.1. № 21, 1996.

Источник: Материалы Международной Крымской конференции «СВЧ-техника и телекоммуникационные технологии», 2006г. 

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