Focal Region Ray Tracing of Conventional and Shaped Lens Antenna

Multibeam lens antennas are useful for 5G mobile communication systems. For multibeam design, feed position determination of specified lens becomes an important subject. The feed position data can be obtained from focal region ray tracing. In this paper, a simple and convenient ray tracing method by using the MATLAB function of “polyxpoly” is proposed. To evaluate the program, focal region ray tracing on conventional hyperbolic planar, spherical convex, and Abbe’s sine condition lens are presented in this paper. For focal region ray tracing, parallel incident ray is considered. The incident ray’s angle is changed from 0 degree to 30 degrees with an interval of 10 degrees. On hyperbolic planar and spherical convex lenses, ray concentration at the focal region is distorted at incident angle of 10 degrees and above. On Abbe’s sine condition lens, good concentration is maintained until 20 degrees. Concentration points agree well with the theoretical value. Therefore, the correctness of the program is ensured

Focal Region Ray Tracing of Conventional and Shaped Lens Antenna

Multibeam lens antennas are useful for 5G mobile communication systems. For multibeam design, feed position determination of specified lens becomes an important subject. The feed position data can be obtained from focal region ray tracing. In this paper, a simple and convenient ray tracing method by using the MATLAB function of “polyxpoly” is proposed. To evaluate the program, focal region ray tracing on conventional hyperbolic planar, spherical convex, and Abbe’s sine condition lens are presented in this paper. For focal region ray tracing, parallel incident ray is considered. The incident ray’s angle is changed from 0 degree to 30 degrees with an interval of 10 degrees. On hyperbolic planar and spherical convex lenses, ray concentration at the focal region is distorted at incident angle of 10 degrees and above. On Abbe’s sine condition lens, good concentration is maintained until 20 degrees. Concentration points agree well with the theoretical value. Therefore, the correctness of the program is ensured

Simulation and Measurement Methods for RCS Estimations of a Scale Model Airplane

In a military context, the radar cross section (RCS) of an airplane is a very important subject. For an RCS estimation object, a scaled-down model is often employed for ease of measurements. Recently, electromagnetic simulations of the RCS has become very convenient because of developments in high-speed calculation methods such as MLFMM and HOBF in electromagnetic simulators employing the MoM algorithm. As for the measurements, high-resolution measurements via the time domain analysis are promising. In this paper, important estimation expressions for use with a scale model are briefly explained. In terms of calculations, comparisons are drawn between the actual calculation abilities of MoM, MLFMM, and HOBF at 18 GHz for a 1/48-scale model. In terms of measurement, a high-resolution measurement system employing a compact range and time domain analysis that is used in this study is explained. Next, the calculated and measured results are compared in order to show the accuracy of the obtained results. The results in vertical and horizontal planes of a scale model are shown at vertical and horizontal polarizations. Moreover, using the calculation method to determine estimates at higher frequencies is also investigated in order to obtain the practical RCS value of a real-sized airplan

Multibeam Array Antenna with Compact Size Butler Matrix for Millimeter-Wave Application

New radio wave technologies of millimeter-wave (mmWave), compact cell size, and multi beam base station are introduced with the recent development of the 5G mobile system. The Butler Matrix (BM) feed circuit is the most preferable candidate for the 5G mobile system since it can achieve multi beam radiation patterns at the array antenna, provide structural compactness and produce good multi beams. The BM circuit is typically built on a single dielectric substrate. However, in this single-substrate structure, the micro strip line connecting several circuit elements in the BM spans over a large area, resulting in significant feeding loss in the millimeter frequency band. In this study, a compact size circuit configuration of BM is proposed, where the original single-substrate structure is modified into a two-substrate stacking structure. The via-hole is designed to connect the two substrates with minimal path loss. The BM is built for the 28 GHz band with four inputs and four outputs. The phase delay is optimized using via-hole to produce the phase difference of ±45º and ±135º. The coupling for the hybrid is -3 dB, while the transmission coefficient of -6 ± 3 is achieved from the BM structure and, the return loss (Sii) for both input and output ports are less than -10 dB. The two-substrate BM is combined with the rectangular patch antenna and the via-hole patch antenna in a planar configuration of 0.5 λ0 spacing to obtain the radiation patterns. When the Port 1 through Port 4 of the BM are fed, four beams are created, with peak gains of 11.2 dBi, 9.87 dBi, 10.2 dBi, and 11.7 dBi, respectively, towards +16°, -35°, +39°, and -12°. The analysis includes the radiation performance from the ideal value and from the BM input. Three-dimensional representations of good multibeam radiation patterns are obtained after each input signal of the BM is fed

Dual-band frequency reconfigurable 5G microstrip antenna

Microstrip Antenna is widely developed and used in modern telecommunications equipment because of its advantages. Microstrip antenna is also used in 5G development which is expected to increase communication capacity and also be able to provide very large data rates. The frequency used in 5G is 28, 38, and 78 GHz. However, the 5G network with high frequency has a weakness: transmitted waves are vulnerable to weather because of their dense waveform. Therefore, the multiband is used to support different frequencies in one antenna. Furthermore, antenna reconfiguration is used to set the antenna to work on a different frequency and adjust different radiation patterns depending on the needs without changing the form of the antenna. This paper proposes the dual-band frequency reconfigurable antenna with RT Duroid 5880 as its substrate using PIN diodes placed between the main patch and secondary patch element and simulated on CST software for 28 GHz and 38 GHz with two conditions, ON and OFF. Both simulated and measured results show that the antenna can work well as intended. During the OFF condition, the antenna only works at 38 GHz, while in the ON condition, the antenna works at 28 GHz and 38 GHz, respectively

Multibeam Array Antenna with Compact Size Butler Matrix for Millimeter-Wave Application

New radio wave technologies of millimeter-wave (mmWave), compact cell size, and multi beam base station are introduced with the recent development of the 5G mobile system. The Butler Matrix (BM) feed circuit is the most preferable candidate for the 5G mobile system since it can achieve multi beam radiation patterns at the array antenna, provide structural compactness and produce good multi beams. The BM circuit is typically built on a single dielectric substrate. However, in this single-substrate structure, the micro strip line connecting several circuit elements in the BM spans over a large area, resulting in significant feeding loss in the millimeter frequency band. In this study, a compact size circuit configuration of BM is proposed, where the original single-substrate structure is modified into a two-substrate stacking structure. The via-hole is designed to connect the two substrates with minimal path loss. The BM is built for the 28 GHz band with four inputs and four outputs. The phase delay is optimized using via-hole to produce the phase difference of ±45º and ±135º. The coupling for the hybrid is -3 dB, while the transmission coefficient of -6 ± 3 is achieved from the BM structure and, the return loss (Sii) for both input and output ports are less than -10 dB. The two-substrate BM is combined with the rectangular patch antenna and the via-hole patch antenna in a planar configuration of 0.5 λ0 spacing to obtain the radiation patterns. When the Port 1 through Port 4 of the BM are fed, four beams are created, with peak gains of 11.2 dBi, 9.87 dBi, 10.2 dBi, and 11.7 dBi, respectively, towards +16°, -35°, +39°, and -12°. The analysis includes the radiation performance from the ideal value and from the BM input. Three-dimensional representations of good multibeam radiation patterns are obtained after each input signal of the BM is fed

Dual-band frequency reconfigurable 5G microstrip antenna

Microstrip Antenna is widely developed and used in modern telecommunications equipment because of its advantages. Microstrip antenna is also used in 5G development which is expected to increase communication capacity and also be able to provide very large data rates. The frequency used in 5G is 28, 38, and 78 GHz. However, the 5G network with high frequency has a weakness: transmitted waves are vulnerable to weather because of their dense waveform. Therefore, the multiband is used to support different frequencies in one antenna. Furthermore, antenna reconfiguration is used to set the antenna to work on a different frequency and adjust different radiation patterns depending on the needs without changing the form of the antenna. This paper proposes the dual-band frequency reconfigurable antenna with RT Duroid 5880 as its substrate using PIN diodes placed between the main patch and secondary patch element and simulated on CST software for 28 GHz and 38 GHz with two conditions, ON and OFF. Both simulated and measured results show that the antenna can work well as intended. During the OFF condition, the antenna only works at 38 GHz, while in the ON condition, the antenna works at 28 GHz and 38 GHz, respectively

Wideband characteristics of density tapered array antennas

In this paper, wideband characteristics of density tapered arrays are clarified by comparing directly the array factors and radiation patterns of 3 tapered arrays structures with array factors and radiation patterns of equally spaced arrays. Calculated results for a density tapered distribution array consisting of 30 elements claims that the array can perform within a bandwidth of 2.5:1 with grating lobe levels lower than -7.8 dB. Additionally, this paper shows a method of determining the effectiveness of unequal spacing arrays in the design of actual antennas. The method is based on calculation and analysis of input impedance of array elements caused by mutual coupling effects among array elements