Beam Steering Using Active Artificial Magnetic Conductors: A 10-Degree Step Controlled Steering

Abstract

An Active Artificial Magnetic Conductor (AAMC) is presented to steer the radiation pattern of a printed dipole working at 2 GHz. The elements that generates the phase shift are a set of Varactor Diodes, which are characterized using its spice model in order to obtain a phase shift-capacitance mapping. Overall beam steering of +/-40 • with a step size of 10 • is achieved. A circuit model that describes any multilayer substrate AAMC unit cell, which uses fist form of Foster's theorem along with transmission line theory, is proposed. Our work is suitable to be used as low profile antenna; for example, street furniture antennas, which are located on the facades of houses or buildings, so that they can be visually mixed up with signs or advertisements. Simulations have been validated using a prototype consisting of an array of 22x14 AAMC elements; the overall structure measures 1.9λ 0 x1.21λ 0. This reflector will generate a phase gradient in its columns, which will modify the reflection angle of an incident electromagnetic wave in the H-Plane. Beam switching control has been achieved using suitably amplified LPF PWM signals generated by two Arduino modules. A printed dipole with a Fractional Bandwidth of 17% is designed and manufactured to illuminate the structure at a distance λ 0 /4 above the surface. Far-field radiation patterns and reflection coefficients have been measured in an anechoic chamber using a spherical system. These compare favorably with simulations performed using the Time Domain solver in CST Microwave Studio.

Realization and validation of continuous tunable metasurface for high resolution beam steering reflector at K‐band frequency

“…Beam‐steering work based on continuous phase design, at 2 GHz with a resolution of 10° 30 was recently published. Another recent work at X‐band based on discrete phase design using PIN switch, which is inherently limited in terms of resolution, introduced resolution of 10° 31 .…”

Ultra-Wideband Reconfigurable X-Band and Ku-Band Metasurface Beam-Steerable Reflector for Satellite Communications

“…Using a dielectric substrate with ε r = 2 and reducing the unit cell and patch sizes reduces the value of C int [11,[17][18][19]36]. The reduction in the patches prevented the varactor from being placed directly on the adjacent patches' edges (blind pad), as in other works [8,15,28,30]. In this design, the distance between the unit cell patches edges was 1.34 mm, while the varactor length dimension is 0.76 mm [42].…”

“…On the other hand, a large TC allows for a reduction in Q and unit cell losses while maintaining a high dynamic phase reflection range. Several methods add reconfiguring and tuning to MS, such as PIN switches, MEMS switches, liquid crystal materials, piezoelectric materials, and varactor diodes [8,9,[12][13][14][15][16][17][18][19][20][21][22]. The liquid crystal method is used in the K-band and above and can be realized in MS as a tuning dielectric substrate, without any external element in the front, but is more challenging to implement [16].…”

“…A varactor diode allows for a continuous and high-tuning-capacitance ratio and fits the continuous reflection phase method in the proposed MS reflector [8,14,15,[17][18][19][28][29][30]. The varactor diodes allow for high-frequency work up to 70 GHz, a conventional PCB assembly, and extremely low consuming power [31], and thus leads to a focus on the varactor diode in this study.…”

“…A reconfigurable MS reflector based on varactor diodes as a tuning element is well known with many published implementations operating at frequencies of up to 6 GHz [8,15,28,29], with very few at X-band and above [18,30,34], where one of them [34] is categorized as a sparse MS and not as a classic MS. Such implementations in the X-band and above will improve satellite communications' quality of service (QoS) in the X-band and Ku-band [35].…”