Multi-band and wide-band metamaterial absorber for radar cross section reduction of an antenna

Metamaterial is a periodically arranged of unit cells with adjustable electric permittivity and magnetic permeability, which is enabled the production of electromagnetic (EM) materials with properties not observed in nature. A few types of metamaterials are used for different applications; High Impedance Surface (HIS), Artificial Magnetic Conductor (AMC), Frequency Selective Surface (FSS) and Metamaterial Absorber (MA). The aim of the MA is to decrease EM wave reflect to source by minimizing the reflection and eliminating the transmission. The transmission is blocked by the ground plane while the reflection is minimized depend on the impedance matching between the surface impedance and free space impedance. The MA is applied in Radar Cross Section (RCS) reduction to be invisibly tracked by the radar. Unfortunately, the recent studies are successfully achieved RCS reduction with either maintained or decreased the gain of the antenna. Therefore, this research is focused on the designed of multi-band MA and wide-band MA with high absorption for RCS reduction at the same time to enhance the gain of the antenna. The multi-band MA is designed based on bar patch, which is printed on Taconic TLY-5 with the thickness of 1.52 mm. The bar patch is rotated anticlockwise from 0o to 90o in 15o increment to understand the structure's absorption spectrum. At rotation of 45o, the bar patch MA is slotted to develop a multi-band MA. The multi-band MA is successfully maintained high absorption at each resonances; 3.98 GHz, 4.81 GHz, and 5.80 GHz with absorption of 99.94%, 99.88%, and 99.66% respectively. Then, the wide-band MA is designed based on double arrow connected with a lump resistor, which is printed on Taconic TLY-3 with the thickness of 0.25 mm. Due to the inherent limitation during fabrication and utilization in real applications, the resistor is replaced by the thin line to connect both arrows to represent the lump element resistance. A wide-band MA is resonated from 3.87 GHz to 11.25 GHz with triple absorption peaks at 4.17 GHz, 6.09 GHz, and 10.30 GHz with absorption capability of more than 99%. Then, the Meandered Dipole Antenna (MDA) is designed at 5.80 GHz to integrate with multi-band MA or wide-band MA to study the RCS reduction and gain enhancement. Both integration are successfully achieved more than -25 dBsm of low RCS apart of enhanced more than 3 dB gain of the antenna. Therefore, the multi-band MA and wide-band MA with high absorption turns out to be suitable for a wide variety of potential applications for Low Observable Technology (LOT) in stealth communication technology

Spectrum Absorbency of Metamaterial Perfect Absorber

A triple-band metamaterial perfect absorber was introduced. The single meta-pattern based on gold-bar shaped was designed on the 0.02λ Taconic TLY-5. The gold-bar shaped was designed horizontal initially was then being rotated anti-clockwise from 0o to 90o to analyse and understand the variation of absorption spectrum. Dual band perfect metamaterial absorber was achieved at 45o. Then, the gold-bar shaped was slotted at both end to develop triple-band metamaterial perfect absorber. The slotted gold-bar shaped was evaluated three absorption peaks: 99.94%, 99.88% and 99.66% at 3.98 GHz, 4.81 GHz and 5.33 GHz, respectively. This however, shifted to the 3.96 GHz, 4.80 GHz and 5.33 GHz with absorbency 99.79%, 99.95% and 99.90% for the measured structure. Both simulated and measure results were achieved absorbency over 99% which was almost perfect absorption (≈100%). These properties are expected to be used in practical applications such as satellite and radar communications transmission. These properties of the metamaterial absorber could increase the functionality of the metamaterial absorber to be used in any application especially in reducing radar cross section for stealth application

IMPROVEMENT OF DIPOLE ANTENNA GAIN USING 8 CBU AMC-EBG AND 8 CBU FSS

This paper investigates the performances of dipole antenna incorporated with and without 8 CBU AMC-EBG and 8 CBU FSS at 5.8 GHz. The designs are simulated on Rogers RO 3010. Due to the flexibility of the material used as a substrate, the effect of a different angle is investigated. Both 8 CBU AMC-EBG and 8 CBU FSS act as reasonably good ground plane for the dipole antenna and help improving the realised gain and improve the radiation patterns by push the front lobe at the same time reduce the side lobes. The maximum improvements led by dipole antenna with 8 CBU AMC-EBG thus 8.543 dB of realised gain achieved and the front lobe is pushed higher and the side lobe is significantly lowered than with 8 CBU FSS. The designs of dipole antenna with 8 CBU AMC-EBG and 8 CBU FSS can be applied as high gain atenna for Intelligent Transport System (ITS)

A Review: The Development Of Metamaterial Absorber

A metamaterial is an artificial resonant structure that is designed to obtain specific characteristics which are not naturally occurring in nature. One of the applications is metamaterial absorber, which offers benefits over conventional absorbers. Metamaterials absorber is a structure that attenuates the energy in electromagnetic waves, soak up the incident energy, convert into heat and reduce the energy reflected back to the source. Various designs on metamaterial absorber have been investigated exhibiting different characteristics; single-band, multi-band, as well as broadband. Starting from thick and rigid substrates, followed by a thin and also flexible substrate materials are being considered. Perfect absorbency is achieved when the surface impedance of the structure equal to the free space impedance. Different methods in introducing the loss in an absorber; lumped resistor, resistive pattern and lossy dielectric. These unique characteristics of metamaterial absorber enable wide applications in various technologies

Dipole Antenna backed by 8-CBU AMC-EBG and 8-CBU FSS at 5.8 GHz

This paper investigates the performances of dipole antenna, incorporated with and without 8-Connected Branches Uniplanar Artificial Magnetic Conductor-Electromagnetic Band Gap (8-CBU AMC-EBG) and 8 Connected Branches Uniplanar Frequency Selective Surface (8-CBU FSS) at 5.8 GHz. The designs are simulated on Arlon AD-350 with permittivity, ɛr = 3.50, thickness, h = 1.016 mm and tangent loss, δ = 0.0026. Due to the flexibility of the material used as a substrate, the effect of different angle is investigated. Both the 8-CBU AMC-EBG and 8 the CBU FSS act as a reasonably good ground plane for the dipole antenna and help to improve the realized gain and the radiation patterns by pushing the front lobe, while at the same time reducing the side lobes. The maximum improvements led by dipole antenna with 8-CBU AMC-EBG are 8.54 dB of realized gain is achieved and approximately 6.53 dBi of the directivity of front lobe is pushed higher than the dipole alone while the side lobe is significantly lower than with 8-CBU FSS. The designs of 8-CBU AMC-EBG and 8-CBU FSS can be applied to dipole antenna application such as Wi-fi and other on-body communication devices

Spectrum absorbency of metamaterial perfect absorber

A triple-band metamaterial perfect absorber was introduced. The single and simple structure based on gold-bar shaped was designed on the 0.018λ Taconic TLY-5. The gold-bar shaped was designed horizontal initially was then being rotated anti-clockwise from0oto 90oto analyze and understand the change of absorption graph. Dual-band perfect metamaterial absorber was achieved at 45o. The fundamental and third harmonic magnetic resonances caused the low and high frequency peaks, respectively. Then, the gold-bar shaped was slotted at both end to create triple-band metamaterial perfect absorber. The slotted gold-bar shaped was evaluated in three absorption peaks: 99.94%, 99.88% and 99.66% at 3.98 GHz, 4.81 GHz and 5.33 GHz, respectively. This, however, moved to the 3.96 GHz, 4.80 GHz and 5.33 GHz with absorbency 99.79%, 99.95% and 99.90% for the measured structure. Both simulated and measure results were achieved absorbency over 99%, which was almost perfect absorption (≈100%). These properties are expected to beused in real-world applications such as satellite and radar communications transmission, particularly in lowering radar cross-section for stealth applications

Improvements Of Trapezoid Antenna Gain Using Artificial Magnetic Conductor And Frequency Selective Surface

This paper presents the performance enhancement of the trapezoid antenna with Artificial Magnetic Conductor (AMC) and Frequency Selective Surface (FSS). The antenna, AMC and FSS structures are printed on 0.254 mm of RT/Duroid 5880 high frequency laminate. The performances of the antenna with and without AMC and FSS were evaluated. Three cases are analyzed; antenna alone, antenna with AMC and antenna with AMC-FSS. The 2x3 arrays of AMC and AMC-FSS were positioned at the back of the antenna with 6 mm air gap. The antenna alone works at 12 GHz, and shifted to 12.35 GHz and 12.33 GHz for case 2 and case 3, respectively. Despite the shift in the resonance, the antenna is still operating well at 12 GHz with a return loss -16.70 dB for case 2 and-16.84 dB for case 3. Case 3 effectively enhanced the antenna gain from 4.43 dB to 6.74 dB and contributed to a directive antenna. Moreover, case 3 also successfully reduced the radiation of the antenna that penetrates into human body as the antenna is applied for on-body applications

Dipole Antenna Backed By 8-CBU AMC-EBG And 8-CBU FSS At 5.8 GHz

This paper investigates the performances of dipole antenna, incorporated with and without 8-Connected Branches Uniplanar Artificial Magnetic Conductor-Electromagnetic Band Gap (8-CBU AMC-EBG) and 8 Connected Branches Uniplanar Frequency Selective Surface (8-CBU FSS) at 5.8 GHz. The designs are simulated on Arlon AD-350 with permittivity, ɛr = 3.50, thickness, h = 1.016 mm and tangent loss, δ = 0.0026. Due to the flexibility of the material used as a substrate, the effect of different angle is investigated. Both the 8-CBU AMC-EBG and 8 the CBU FSS act as a reasonably good ground plane for the dipole antenna and help to improve the realized gain and the radiation patterns by pushing the front lobe, while at the same time reducing the side lobes. The maximum improvements led by dipole antenna with 8-CBU AMC-EBG are 8.54 dB of realized gain is achieved and approximately 6.53 dBi of the directivity of front lobe is pushed higher than the dipole alone while the side lobe is significantly lower than with 8-CBU FSS. The designs of 8-CBU AMC-EBG and 8-CBU FSS can be applied to dipole antenna application such as Wi-fi and other on-body communication devices

ANDROID BASED ANTENNA POSITIONING SYSTEM

To receipt the strongest possible signal, the antenna must be pointed at a precise angle in the direction of transmitter for effective wireless communication. If the movement of the antenna is controlled manually, there is a problem of aligning it at the optimum position to receive the strongest possible signal especially in remotely located areas. To overcome the difficulty of adjusting manually, Android Based Antenna Positioning System is proposed to remotely control the position of antenna by using an android phone. Two 12 V 28BYJ-48 stepper motors and ULN2003 drivers are demonstrated as a rotator to move the antenna in azimuth and elevation directions simultaneously. The commands provided from a web page through android phone are sent to the motors in real time via NodeMCU V3 microcontroller. MPU6050 sensor is mounted on the antenna to determine its position then the data collected is uploaded to Blynk application. When the antenna is positioned at specified direction in the direction of horn antenna (transmitter) based on the angles, speed and direction of motors’ movement, the strongest possible signal strength of antenna at specific frequency of 2.4 GHz can be determined using spectrum analyzer. When the antenna is positioned at X=27.52˚, Y=285.63˚, and Z=171.71˚, it has the strongest signal strength of -36.62 dBm as well as the gain of 1.713 dB. The stronger the signal strength of antenna, the higher the gain and the higher the quality connection

Wide-Band Metamaterial Perfect Absorber Through Double Arrow Shape Printed On A Thin Dielectric

A wide-band metamaterial perfect absorber was introduced. The dual arrow shapes and the ground plane were in between the 0.0035λ TLY-3. Lump element technique was applied to enhance the absorption bandwidth, which was connected between both of the arrow structures. The limitation during fabrication process in using lump element, had seriously restricted its practical applications for microwave absorption. Then, a very thin line was connected between both arrow structures to represent the resistance by lump element which was expected to ease the fabrication process and practical applications as well. Four cases were analyzed: double arrow, double arrow with lump connected, double arrow with lump connected and 9 mm air gap, and thin line connected with 6 mm air gap. The fourth case achieved the highest operational absorbency frequency, which developed about 7.38 GHz (3.87 GHz to 11.25 GHz) approximately to 7.38 GHz. Three resonant frequencies were achieved; 4.17 GHz, 6.09 GHz and 10.30 GHz with perfect absorbency. These properties are expected to be used in practical applications such as satellite and radar communications transmission. These properties of the metamaterial absorber could increase the functionality of the metamaterial absorber to be used in any application especially in reducing radar cross section for stealth applicatio