RU199124U1 - Microwave protective device - Google Patents

Abstract

The utility model relates to microwave technology, in particular, to microwave protection devices. The microwave protection device contains a band-pass filter based on half-wave U-shaped hairpin resonators, in one or more resonators of which a limiting p-i-n diode is included. This diode is connected between the areas opposite to the middle of the center conductor of the resonator. The technical result is a decrease in weight and size parameters. 1 wp f-ly, 1 dwg

Description

The utility model relates to microwave technology and can be used as a protective device at the input of receiving channels of electronic equipment to protect against high-level microwave power signals, as well as signals with frequencies outside the operating bandwidth (out-of-band interference).

One of the main elements of the input part of microwave receivers are protection devices (UZ) against a high power level of the input signal and a bandpass filter (BPF), which provides protection against out-of-band interference (see, for example, L.G. Gassanov and other Solid-state devices Microwave in Communication Technology - M .: "Radio and Communication", 1988, pp. 51, 142). There are numerous design options for such devices, including ultrasound based on semiconductor control elements, mainly diodes, and PPFs made on coupled resonators in the form of sections of quasi-symmetric (symmetric) transmission lines. In the complex, both of these devices, connected in series in the receiving path, have rather large dimensions, which is a significant drawback with modern stringent requirements for the weight and size parameters of electronic devices for various purposes.

This drawback is partially eliminated in devices that combine the functions of ultrasound and PPF (see RF Pat. No. 2395872 "Microstrip protective device"; RF Pat. No. 2258278 "Diode microwave power limiter"; RF Pat. No. 2456719 "Selective protection device for counter rods ").

Such devices include the closest to the claimed protective device, known from the publication Lee W. Cross Design of microwave Front-End Narrowband Filter and Limiter Components // A dissertation submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Engineering, 2013, p. 102.

The above-mentioned device is made in the form of a microstrip filter on three hairpin half-wave U-shaped resonators, the free ends in one or all resonators are connected through a gas-discharge limiting element (plasma limited element).

The main disadvantage of the known device is its large dimensions due to the use of a gas-discharge limiting element with dimensions (4.6 × 4.6 × 2) mm, developed for use at frequencies of ~ 870 MHz. Obviously, with an increase in the operating frequency, the dimensions of the restricting element will become decisive for the dimensions of the protective device as a whole, which at a microwave wavelength of less than 9 mm will be impossible to implement.

In addition, the known device can perform its main function only conditionally, since the triggering threshold of the limiting mode begins with an input power of the microwave signal of 28-29 dbm, which is significantly higher than the allowable level for known input low-noise amplifiers (receivers). It should also be noted a significant increase in filter losses when a gas-discharge device is installed on it (~ 1.7 dB) and a rather long time for switching on / off states. (on the order of a few microseconds).

The technical effect to achieve which the patented utility model is aimed at is to reduce the weight and dimensions of the device.

This effect is achieved by the fact that in a microwave protective device, made in the form of a microstrip bandpass filter on half-wave U-shaped hairpin resonators, in one or more resonators of which between the sections of the central conductor opposite to its middle, a limiting element is installed as a limiting element used pin diode.

The control element is installed mainly in the output resonator (resonators) of the filter.

The proposed solution is illustrated by drawings. FIG. 1a shows a schematic representation of one of the possible implementations of the input protective device, where 1 is the central conductor of one of the hairpin resonators of the band-pass filter, D1 is a control element, mainly a p-i-n diode.

The device works as follows. In the absence of a powerful signal, diode D1 is a large resistance and does not affect the characteristics of the filter. When a high-power signal arrives, diode D2 opens (direct current is closed through the central conductor 1) and short-circuits part of the resonator, due to which the natural (resonant) frequency of the latter is re-tuned, and the signal passing through it at the operating frequency (receiving frequency) sharply decreases.

Obviously, the maximum amount of suppression of the signal power in the proposed device when using one diode in one resonator has a finite value. It has been experimentally established that in this case it can reach 40 dB. An additional diode can be used to increase suppression (D2 in Fig. 1b). In this case, the maximum allowable power level of the input signal is automatically increased.

An additional diode (D3 in Fig. 1c) can also be installed in another resonator of the filter. If necessary, you can use both options for switching on additional diodes at the same time.

Since a diode is a non-linear element, in the presence of out-of-band interference on it, parasitic harmonics can occur that fall into the operating frequency range. Therefore, it is preferable to install diodes in the output resonators of the filter using the selection of signals by its input resonators.

Examples of implementation.

1. Designed and manufactured a band-pass hairpin filter, consisting of five resonators on a polycor substrate, intended for operation in the 3 GHz range, with a bandwidth of 400 MHz. In its fourth resonator from the input, the MA4L032-134 diode is connected between the opposite sections of the central conductor at a distance of ~ λ / 6 from its middle. (Fig. 1a).

At an input signal level of ~ 200 W (τ≈30 μs, Q = 10), the signal suppression increased by 32 dB from the initial filter loss level with a weak signal (~ 1 dB).

2. Designed and manufactured a band-pass filter similar to that described in example 1. In the same resonator as in example 1, two MA4L032-134 diodes are installed between points at a distance λ / 6 and λ / 8 from the middle of the resonator (Fig. 1b). At the same input signal power, the suppression increased to ~ 37 dB.

3. Designed and manufactured a band-pass filter similar to that described in examples 1, 2. In the adjacent, fourth and fifth resonators of the filter, MA4L032-134 diodes are installed between the points located at a distance of ~ λ / 8 from the middle of the resonator (Fig. 1c) ... The suppression at the same input signal power increased to ~ 47 dB. The output signal power was ~ 4 mW.

Therefore, in the claimed device, two diodes are enough (instead of three gas-discharge elements in the prototype) to provide a suppression level of up to 50 dB or more (with the corresponding position of the diodes in the resonators). In this case, the output signal level is ~ 4 mW, which is significantly lower than that of the prototype device, with a comparable input signal power.

Thus, the proposed protection device is a power limiter - a preselector that effectively performs the functions of the latter, incl. providing increased protection against out-of-band interference. Obviously, when a gas-discharge restricting element is used in the claimed design, the dimensions of the protective device will increase significantly.

Claims (2)

1. The protective device of the microwave signal receiver, made in the form of a microstrip band-pass filter on half-wave U-shaped hairpin resonators, in one or more resonators of which a limiting element is included between the sections of the central conductor opposite to its middle, characterized in that the limiting element is a semiconductor pin diode. 2. The microwave protective device according to claim 1, characterized in that the p-i-n diode is installed in the output resonator.

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