Rapid Test Method for Multi-Beam Profile of Phased Array Antennas

The measurement of the phased array antenna (PAA) is completely different from the traditional antenna, due to its multi beam patterns. Usually, each beam pattern of the PAA needs a separate measurement, which makes the overall time extremely long. Thus, the traditional method can no longer meet the efficiency and cost requirements of new PAA measurement. In this paper, a pattern reconstruction method is proposed which significantly reduce the measurement time of multi-beam PAAs. With the known array element patterns (AEP) and theoretical weighted port excitation of the beams, any beam pattern can be predicted by measuring only a certain beam pattern, due to the element excitation coefficient (including the matching, mutual coupling, and manufacturing factors, etc.) of the specific PAA being calculated. The approach has low reconstruction error in term of beam pointing accuracy, side lobe, and co-polar and cross-polar patterns while being validated for large scanning range. Through theoretical derivation and experiments, the effectiveness of the method is verified, and the testing efficiency of the phased array antenna can be improved by 10 times or even more.

INCREASE IN ACCURACY OF MEASURING AIR OBJECTS ANGULAR COORDINATES DURING MULTICHANNEL RECEPTION OF RADIO-LOCATION SIGNAL

Radars with a phased array antenna (PAA) which performs multi-channel radar signal reception are effective means of obtaining radar information about air objects in difficult conditions of air and jamming environment. Radar surveillance for radars with PAA is accompanied by a significant negative effect of tropospheric inhomogeneity, which causes a decrease in the accuracy of measurements of azimuth angles and air object‟s position due to fluctuations of the phase front of the received wave reflected from an air object. According to the results of research, the hypothesis of a normal distribution law of these fluctuations is accepted. The paper presents the results of estimating the root mean square errors of measuring the angular coordinates of the air object, which occur if the fluctuations of the phase front of the received signal‟s wave are not taken into account and analyzes the possibility of reducing such errors when the fluctuations are considered. The possibility of optimizing the angular measurements of air objects in digital radars with PAA is shown, which consists in taking into account the fluctuations of the phase front of the received signal in the algorithm of discrete (fast) Fourier transform, which is widely used to provide spatial measurements in modern digital radar stations. The results of previous studies were generalized, which makes it possible to evaluate the possibility of increasing the accuracy of angular measurements of air objects during multichannel reception of a radar signal in difficult conditions of radar operation.

Eight-element liquid crystal based 32 GHz phased array antenna with improved time response

Phased array radar systems are used for a wide variety of applications including the precise tracking of airborne craft for air traffic control and providing accurate atmospheric condition information important in weather forecasting. Reducing the cost and size of these radar systems will open new fields to the use of this technology. Using phase control implemented through liquid crystal materials we have created a compact, phased array radar system operating in the microwave range. We report on the construction and testing of a linear, eight element phased array antenna system operating at 32 GHz with element phase controlled by a dual frequency nematic liquid crystal media used as a tunable dielectric. The system was designed using CST Design Studios and Ansys HFSS software. Dual frequency liquid crystals are used to improve beam steering response times. We demonstrate 42 millisecond beam switching times, defined as the time to change the beam focus from one point to another point, controllable beam formation, and beam steering profiles consistent with analytical results and simulation models. The device footprint is a square with sides 9.5 cm long and a thickness less than 2.5 mm. Such a module is easily stackable to create an 8 × 8 phased array system. Our design incorporates a modular construction using PCB for the antennas and input circuitry and a liquid crystal phase control cell with microwave glass substrates. This design simplifies design, construction, and testing as compared to on-glass designs. The device shows an improvement in point-to-point scanning speeds by a factor of 3 as compared to similar liquid crystal based devices and provides continuously variable tuning. Such a device can be used in a system for reduced visibility, directional range finding suitable for automobile collision avoidance systems and rotary wing aircraft landing aids.