Antenna array with switching scanning in elevation plane

It is known that the most reliable communication in hard-to-reach places such as the Arctic, Tundra, Taiga is satellite communication [1-5]. Therefore, for satellite communications, it is necessary to develop your own antenna arrays. This article discusses a waveguide-slot antenna array with a Luneburg lens for a mobile satellite communications terminal, which provides a continuous and stable signal. This antenna operates in the 10.9 to 14.5 GHz frequency range. Possesses vertical polarization. The overall dimensions of the antenna array are: diameter of the diagram-forming lens 256 mm (thickness 5 mm, material FLAN 2.8 (epsilon 2.8, tangent delta 0.0015)); waveguide length 600 mm (internal section 10.5 mm by 5 mm, filling FLAN 2.8). Slotted waveguide antennas and lens are made of standard FLAN 2.8 material (epsilon 2.8, tangent delta 0.0015) 5mm thick, foiled on both sides. There are 17 coaxial cables to the HF switch (equal lengths are not required), the scanning step in elevation is 5 degrees. When using 54 waveguide-slot antennas and 18 switch inputs, a scanning sector in elevation of 90 degrees is provided. All the nodes were pre-modeled separately a cylindrical Luneburg lens with suitable waveguides, excited by slits; slotted waveguide antennas; coaxial-waveguide transitions.

Waveguide Slot Feed Section for Antennas with Circular Polarization

Modern information systems use circularly polarized signals. Among them are tracking systems, remote sensing systems, satellite television systems. The use of circularly polarized signals in satellite communication systems allows to combat multipath propagation of signals in the environment, which reduces interference. By reflecting signals from different objects, they transform their polarization. This makes it possible to reduce signal distortions in the receiving device, which increases the information capacity of wireless data transmission channels. In satellite communications, multi-band horn antennas are widely used. The use of such devices allows transmission of signals with high power and reception of signals with low noise level. Such systems are used as powering a reflector antenna with a wide bandwidth. For such applications, a horn antenna device has been proposed in which signals can be excited that produce left-hand circularly polarized signals and right-hand circularly polarized signals. The proposed horn antenna was powered through a slot that was cut in a rectangular waveguide. Due to the 45º angle of the slot, the antenna can generate signals with double circular polarization. The proposed design can be used without polarizing devices, which must be developed separately. The developed design of the horn antenna at the operating frequency of 16 GHz provides a peak antenna gain of 24 dB for signals with right circular polarization and a peak value of a gain of 18 dB for signals with left circular polarization. The polarization isolation is greater than 12 dB. Moreover, at the operating frequency, the maximum value of the reflection coefficient takes on a value of –17 dB. Thus, the developed waveguide slot feed section for antennas with circular polarization provide rather good characteristics in a narrow frequency band.

A Review on Improved Design Techniques for High Performance Planar Waveguide Slot Arrays

Planar waveguide slot arrays (WSAs) have been used since 1940 and are currently used as performing antennas for high frequencies, especially in applications such as communication and RADAR systems. We present in this work a review of the most typical waveguide slot array configurations proposed in the literature, describing their main limitations and drawbacks along with possible effective countermeasures. Our attention has been focused mainly on the improved available design techniques to obtain high performance WSAs. In particular, the addressed topics have been reported in the following. Partially filled WSAs, or WSAs covered with single or multilayer dielectric slabs, are discussed. The most prominent second-order effects in the planar array feeding network are introduced and accurately modeled. The attention is focused on the T-junction feeding the array, on the effect of interaction between each slot coupler of the feeding network and the radiating slots nearest to this coupler, and on the waveguide bends. All these effects can critically increase the first sidelobes if compared to the ideal case, causing a sensible worsening in the performance of the array.