RU2452063C2 - Broadband vlf-mf range receiving ferrite antenna - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: N -boosting transformers (secondary windings whereof are connected in series) are connected to the broad coil of the broadband receiving ferrite antenna via N>1 of its parallel terminals located along the coil. According to the second version the broad coil is designed to be composed of N>1 more narrow coils each equipped with a boosting transformer, the secondary windings of the N transformers connected in series. The antenna winding inter-coil capacity is reduced both due to the transformers secondary windings designed to be one-layered and to distribution of this capacity between the transformers.

EFFECT: receiving ferrite antenna broadbandness enhancement.

2 cl, 2 dwg

Description

The device relates to radio technology and can be used in the field of radio communications, radio navigation or radio direction finding.

Magnetic antennas (MA) with ferrite cores, which have several advantages over electric type antennas, are often used to receive signals of LED, LW, and MW bands [1, 2, 3]. In particular, due to ferrites, such antennas are small in size, they are less susceptible to the strong electrical component of the interference field from nearby sources. These antennas have a selective radiation pattern in the form of a figure of eight, which determines their use for navigation and direction finding.

However, the broadband MA is small, their effective height is of a pronounced resonance character with a maximum at a certain frequency at which the antenna sensitivity is the best. Therefore, for reception in the entire SDV-SV range, it is necessary to use two antennas designed for reception in each of the ranges, which increases the cost of the antenna system and creates certain inconveniences of operation.

Creating a broadband antenna that continuously covers the entire SDV-SV range is a difficult technical task. The fact is that in order to achieve high sensitivity in the SDD range, especially underwater reception, when using a ferrite rod that is still acceptable along the length (not more than 1 m), the winding on the rod should contain hundreds of turns (up to 500 or more). As a result of a significant increase in the inductance of the winding and inter-turn capacitance, the resonant frequency of the antenna decreases to 100 kHz or less, which leads to a strong suppression of signals with frequencies above the resonant frequency. In addition, the electric length of the winding wire (taking into account the shortening of the wave near the ferrite) at high frequencies becomes comparable with the wavelength. The half-waves of voltages of different polarity induced by the field in the wire begin to be subtracted from each other and lead to a decrease in the total voltage at the output of the winding up to zero at some frequencies, which also reduces the upper operating frequency of the antenna.

The purpose of the invention is the expansion of the working range of the ferrite LED ultra-violet antenna to the microwave range.

Ferrite antennas are known [1, 2], in which, in order to reduce inter-turn capacitance, the winding on a ferrite rod is performed in sections. The disadvantage of this solution is a noticeable increase in the length of the winding with the same number of turns.

Known ferrite MA [1, 3], in which to reduce its own inductance it is proposed to carry out the winding sections, and between the sections include capacitors. As a result of the similarity of a traveling wave line with a wave impedance consistent with the load impedance, the frequency response of the antenna is aligned in the operating frequency range. However, the calculations for the ADD antenna show that due to phase shifts in the sections, the upper boundary frequency of the MA is limited to several hundred kilohertz.

Known ferrite antennas with a variable number of turns of the winding [1, 2]. With an increase in the reception frequency, the number of turns decreases with the switch. The need to control the antenna complicates the receiving path. Such an antenna will work well with only one radio receiver, from which it will receive control signals. An antenna tuned, for example, using a capacitor of variable capacitance [1] will also have the same drawback.

The device closest in technical essence (prototype) is a ferrite antenna [4], containing one wide coil of winding on a ferrite rod and a step-up transformer connected to it on a ferrite ring with a transformation ratio of 1: W. The perimeter of the cross section of the ferrite ring is usually less than the perimeter of the cross section of the rod, which allows for the same number of turns W to reduce the length of the winding and thereby increase the resonant frequency of the antenna. The disadvantage of such an antenna is the difficulty of implementing a transformer with a high transformation ratio (500 and higher), since the inner circumference of the rings is limited by their actual sizes and does not allow a large number of turns to be wound in one layer (more than ≈200). Multilayer winding increases the inter-turn capacity, and its sectioning reduces the coupling coefficient between the transformer windings. All of these factors impair broadband.

To increase the broadband, it is proposed to include N transformers distributed evenly along the wide coil in parallel with a wide coil (width up to 0.7 of the rod length), and turn on the secondary single-layer transformer windings in series.

A positive effect of the proposed technical solution is that even with a limited number of turns on one transformer W ₁ equal to, for example, 200, due to the proposed inclusion of N such transformers (N≈2-5), the total number of turns W ₀ = N · W ₁ can reach 1000. Moreover, the minimum inter-turn capacitance will be ensured both by performing single-layer windings in each transformer and by N-fold sectioning (distribution between N transformers) of the total secondary winding.

Figure 1 shows the appearance of the antenna with three transformers, where are indicated by numbers:

1 - ferrite core;

2 - a wide coil with three parallel leads;

3 - transformers with secondary windings;

4 - conclusions of the secondary windings of transformers.

The antenna works as follows.

Induced on a wide coil 2, the voltage U _{vit is} supplied simultaneously to the inputs N of the transformers connected in parallel 3. The primary winding of the transformer contains one coil, which is structurally made in the form of a metal sleeve closing the output of the wide coil and passing through the inner hole of the ring. The total coil current I _vit is divided between the terminals (between transformers) approximately equally. The voltage at the output of each transformer (its secondary winding) will be equal to U _Tr = U _Vit W ₁ . The total voltage at the output of all N secondary windings will be equal to U _o = U _vit · W ₁ · N.

A wide turn can be made of N parts with overlapping or without overlapping ends, figure 2. Each of the parts is connected to its transformer. This embodiment may be easier to manufacture, but without overlapping ends it has a slightly lower broadband.

We estimate the gain from the proposed technical solution. Let the circumference of the ferrite rod be 10 cm. To obtain the necessary sensitivity of the antenna, it is necessary to wind 600 vit. Windings on the ferrite rod. The length of the wire in this case will be l = 10 × 600 = 6000 cm = 60 m. If you use 3 transformers on rings of size 32 × 16 × 8 mm (section perimeter p = 3.2 cm) with 200 turns each, then the total length of the winding will be l = 20 m, which is 3 times less. This means that the upper cutoff frequency of the antenna can be 3 times higher.

At N> 4-5, the gain will decrease, which is associated with an increase in the frequency division of the current of the wide coil I _vit between the transformers. A decrease in current through each transformer by N times is equivalent to an increase in N times the output resistance of a wide coil for one transformer. For normal operation of the transformer, an increase in the inductance of its primary winding will be required, for example, by superimposing several rings or using rings of greater thickness. All these measures lead to an increase in the perimeter of the cross section of the ring, and hence the length of the winding.

Using the proposed technical solution allows you to expand the working range of the LED VHF antenna in the direction of high frequencies up to and including the CB range and thereby reduce the required number of receiving MAs at the facilities.

LITERATURE

1. Khomich V.I. Ferrite antennas. Mass radio library. Issue 721 - M .: Energy, 1969.96 s.

2. Vershkov M.V. Calculation and design of ship radio communication antennas. - L .: Sea transport, 1963, 148 p.

3. Bobkov A.M. Real selectivity of radio channels in a complex jamming environment. - St. Petersburg, Abris, 2001 .-- 216 p.

4. Patent No. 2256264, H01Q 7/08, 2004

Claims (2)

1. Broadband receiving ferrite antenna, consisting of a ferrite rod with one wide turn, the terminals of which are connected to the primary winding of the step-up transformer, characterized in that N step-up transformers are connected to the wide turn through N> 1 of its parallel leads located along the turn, secondary whose windings are connected in series. 2. Broadband receiving ferrite antenna, consisting of a ferrite rod with one wide coil, the terminals of which are connected to the primary winding of the step-up transformer, characterized in that the wide coil is made up of N parts, each of which is connected to its transformer, and the secondary windings of all transformers connected in series.

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