Variants of the zigzag antenna Kharchenko. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / VHF antennas

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At the very beginning of the 60s of the last century, our compatriot Kharchenko K.P. proposed a simple flat zigzag (Z) antenna with good characteristics. Its possible modifications are considered below, including variants with a tuned active reflector.

Author's certificate No. 138277 for an invention called "Band Directional Antenna" was issued to Konstantin Pavlovich Kharchenko in 1961 (according to his application of June 16, 1960). In the same year, materials were published in the journal "Radio" for repetition by radio amateurs [1, 2]. And subsequently, for more than 50 years, the editors repeatedly recalled these publications. Kharchenko's zigzag (Z) antenna has become a milestone among the best developments. It turned out to be not critical to materials and dimensions during manufacture, it has a good agreement with the outgoing cable. It successfully combines multiple elements of an in-phase antenna array with a single feed point.

Despite the excellent electrical and operational characteristics, organized widespread use of zigzag antennas did not occur. In our country at that time, the extended and voluminous directorial Uda-Yaga antennas recognized throughout the world (they are also called the "wave channel") were already massively used, since they

mastered in the production of industrial enterprises. They, as they say now, provided the market. However, the simplicity of manufacturing zigzag antennas and their attractive characteristics, with the information support of the Radio magazine and amateur radio communications, made this antenna accessible even to untrained users.

In the preface of the book "VHF Antennas" [3], published in 1969, K. P. Kharchenko reported that many radio amateurs, using zigzag antennas, received television transmissions in the MV band, including from television centers located 80 120, 200 and even 300 km. Indeed, from the history of technology of that time, one can learn that in areas remote from television centers, zigzag antennas replaced "wave channel" antennas and other structures. In addition, Kharchenko's Z-antennas were also awarded the attention of the military, who took advantage of their positive qualities in radio relay communications in the UHF range.

In recent years, the authors have carried out extensive computer simulation of Z-antennas, including using the MMANA program proposed in the Radio journal. Their constructive execution showed good results. The antennas are adapted to sub-band IV of broadcasting on the UHF. It is at frequencies of 470 ... 582 MHz that analog television broadcasting is most widely conducted and digital television is being deployed.

The most common [3] original zigzag antenna, made with a single-wire fabric with side λ_Wed/4 is shown in Fig. 1a. In the indicated television range (with an average frequency of 525 MHz adopted for simplicity), it has radiation patterns in the horizontal and vertical planes shown in Fig. 2a. The results correspond to the placement of the antenna at a height of 15 m above ground level. The antenna gain is 10,9 dBi and the standing wave ratio is 2,4. Their change in the subrange is shown in Fig. 3a. Elevation, i.e., the elevation of the maximum radiation pattern above ground level, is 6 °.

Fig. 1

Rice. 2 (click to enlarge)

Rice. 3 (click to enlarge)

The efficiency of a zigzag antenna can be increased by improving the directivity by using a reflector screen [3] spaced from the main web by λ_Wed/4, as shown in Fig. 1b. This results in an increase in gain of up to 14,6 dBi. For comparison, similar diagrams and characteristics of the upgraded design are shown in fig. 2b and 3b.

A later version of the original zigzag antenna can be called a double triangular zigzag antenna shown in Fig. 1c. It is one of the best Z-shaped antennas [4], although it has slightly worse characteristics, shown in Fig. 2, c and fig. 3, in. However, the decrease in antenna gain by only 1,4 dBi is compensated in practice by the simplicity and compactness of the design.

The desire to further improve the classical versions of the antenna prompted us to turn to the designs of other frequency intervals, especially to the use of an active reflector. In complex shortwave tuned antennas with linear in-phase horizontal components, identical active reflectors are used, located at λ_Wed/4 from the main canvas. They are connected through phasing circuits, which provide them with a leading shift of currents in phase by 90^о [5]. The direct transfer of such a method to zigzag antennas only leads to a deterioration in performance compared to a passive reflector.

More interesting was the use of a double triangular zigzag antenna with doubled arm sizes for a classical antenna as an active reflector, as shown in Fig. 1d. This solution provided an increase in the antenna gain to 14,83 dBi, a decrease in the level of side lobes, as shown in Fig. 2d, and a significant equalization and improvement of the SWR, which can be seen in Fig. 3, g.

Due to the additional modernization of the active reflector, as shown in Fig. 1e, it is possible to further improve the characteristics of the proposed solution, as shown in Fig. 2d and 3d. This is especially true for increasing the gain and its equalization at the upper frequencies of the interval. In addition, the antenna in the entire subband has an SWR of less than two. Self-production of an innovative sample does not involve difficulties, since its components have been described many times before.

Literature

1. Kharchenko K. Zigzag antenna. - Radio, 1961, No. 3, p. 47, 48.
2. Kharchenko K. Antenna for long-range television reception. - Radio, 1961, No. 4, p. 28, 29, 32.
3. Kharchenko K. P. VHF antennas. - M.: DOSAAF, 1969, p. 77-96.
4. Sidorov I. N. Ideal TV reception in a country house, in a garden plot, far outside the city. - S.-Pb.: Lenizdat, 1998, p. 87-95.
5. Markov G. T. Antennas. - M.: Gosenergoizdat, 1960, p. 455-460.

Authors: V. Milkin, N. Kalitenkov, V. Lebedev, A. Shulzhenko

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