Крехтунов В. М., Русов Ю. С. МГТУ ім. Н. Е. Баумана, вул. 2-а Бауманська, буд 5, Москва 105005, Росія Тел.: (095) 2677596; e-mail: mc_ken@mail333.com

Рис. 4. Діаграми спрямованості рупорнодіелектріческого випромінювача в антеною грат

Fig. 4. Far field patterns of the horn-dielectric radiator in the antenna array

III. Висновок

Розроблено хвилеводно-діелектричні випромінювачі з конічною формою стрижня. Один з випромінювачів призначений для роботи в ФАР Кадіапазона з ширококутним скануванням. Інший випромінювач використовується в елементі ФАР Wдіапазона і забезпечує заданий сектор сканування і придушення побічних головних пелюсток множника антеною решітки.

IV. Список літератури

1. Bounkin В. V., Lemansky A. A. Experience of development and industrial production ofXband passive phased antenna arrays. International Conference on Radar, Paris, 3-6 May, 1994. A.3. Antenna design. P. 20-24.

2.     Вендік О. Г. Антени з немеханическим рухом променя.

М.: Сов. радіо, 1965. -360 С.

3.     Крехтунов В. М., Тюлін В. А. Дифракція електромагнітних хвиль на двумерно-періодичної волноводнодіелектріческой решітці. Радіотехніка та електроніка, 1983, т. 28, № 2, с. 209-216.

4.     Бей Н. А., Хандаміров В. П. Діелектричні стрижневі випромінювачі ФАР. Антени, 2001, Вип.8 (54), с. 6163.

RESEARCH OF DIELECTRIC RADIATORS FOR PHASED ANTENNA ARRAYS

KrekhtunovV. М., RusovYu. S.

Bauman Moscow State University

2-nd Baumanskaya str., Moscow -105005, Russia

Abstract The results of development and experimental research of waveguide-dielectric radiators for flat multi element phased antenna arrays for Ka and W frequency bands are submitted. The Ka-band radiators are intended for phased antenna array with wide sector of beam scanning ±45°. The Wband radiators used in elements of phased antenna array with the cross section sizes less than 1,25X (X is wavelength), have the far field pattern considering mutual coupling of antenna array elements, which allows a ±15° beam scanning.

I.  Introduction

One of the important tasks, solved in phased antenna array (PAA) design, is the development of radiating elements determining the gain of PAA and its change within sector of scanning. In waveguide PAA with ferrite phase shifters as radiators the use of dielectric antennas (waveguide-dielectric radiators (WDR)) is effective [1]. They allow operating with linear and circular polarized waves of an electromagnetic field and provide good matching with free space and with a waveguide. The effects of mutual coupling of elements in the antenna array in a direct and reverse directions are well investigated [2, 3]. In particular, changing the sizes of the dielectric rod it is possible to obtain the required far field radiator pattern.

II.  Main part

The gain of a radiator in an ideal antenna array without material losses can be calculated by the formula:

where S0 an area per one element in the antenna array; Г (9, \ | /) reflectivity factor of a flat homogeneous electromagnetic wave incident upon antenna array from a direction, determined by angles 0,4 / in the spherical coordinates system; X operational wavelength.

Formula shows that when the PAA is matched with free space the far field power pattern of radiator in array is described as cos 9 within the total sector of scanning, where 9 is an angle measured respective to the antenna array normal. This is an ideal pattern of a radiator in the antenna array.

The general recommendations on approximate estimation of the dielectric radiator sizes are given in [4]. It is possible to calculate necessary length WDR from a condition of equality between directivity of single WDR and that of elementary area per one element in the antenna array. For the antenna array with a hexagonal cell this condition results in the following formula:

where L length of a dielectric rod; d4 the antenna array distance; KD parameter, dependent on effective factor of delay of a surface wave, extending along the dielectric rod. Fig. 1 shows the length WDR dependencies on antenna array spacing for different values of parameter KD, and also generalized results of WDR analysis for different values of the antenna array spacing [1].

The methods [3] of WDR calculations are suitable for the dielectric cylindrical and step rods. To provide good WDR matching with free space the dielectric rod is usually manufactured as a cone. The exact calculation of G0(9,i|/) function for conical WDR, considering mutual coupling of elements in the antenna array, represents a difficult electrodynamic problem, so it is expedient to perform experimental selection of sizes for such WDR.

The experimental design of dielectric radiator is performed for Ka-band PAA with elements located in nodes of a triangular array with spacing 0,68 Х. The far field patterns of receive WDR, measured in two orthogonal planes of the antenna array, are represented in the fig. 2. The dielectric rod is made of a material with dielectric permeability sr=2,3 and the length of the dielectric radiator is L=2X.

The experimental design of horn-dielectric radiator is performed for W-band PAA with elements located in nodes of a triangular array with spacing 1,25X. During the research the problem is successfully solved for the suppression of a parasitic interferentional maxima of an array factor arising along the direction 9= -41,5° when the main lobe deviated 15° from antenna array normal. The design of horn-dielectric radiator is shown in fig. 3a, where 1 dielectric rod, 2 horn. The structure of the radiator’s arrangement for investigation the far field patterns is represented in fig. 3 b. The horn-dielectric radiator far field patterns, measured in a plane of the maximal spacing of the structure in a range of operational frequencies fcp±l%, are depicted in fig.4. The dielectric rod is made of a material with dielectric permeability sr=2,5, and the length L of the dielectric rod is equaled to 5X.

III.  Conclusion

The waveguide-dielectric radiators with the conic form of a rod are designed. One of the radiators is intended to operate in a Ka-band PAA within wide scan sector. Another one is used as an element of a W-band PAA and provides the given scan sector and suppression of parasitic interferentional maximums of an array factor in the antenna array pattern.

Джерело: Матеріали Міжнародної Кримської конференції «СВЧ-техніка і телекомунікаційні технології», 2003р.