Beam‐reconfigurable crescent array antenna with AMC plane

A beam‐reconfigurable crescent array antenna with AMC plane is presented for application at 9.41 GHz. The unit cell of the AMC plane is modeled based on a square patch integrated with rectangular ring slot with mirrored C‐shaped structures, placed between two layers of Taconic TLY‐5 substrate and located near to the main radiating element. The presented AMC design is achieved an operating bandwidth of 2.82 GHz (30%) with a center frequency of 9.41 GHz. It is found that the AMC plane can reduce the thickness of the structure in comparison to the use of a conventional ground plane, which leads to the overall compactness size of the proposed antenna of 1.1λ × 2.57λ. Moreover, through the implementation of 12 × 4 AMC unit cell, the proposed antenna improved its performance with a maximum gain and total efficiency of 10.5 dB and 97%, respectively. Meanwhile, the antenna reconfigurability is realized by integrating RF MEMS switches on its right and left arm symmetrically. The presence of a T‐shaped Yagi‐Uda‐like parasitic further widened the beam steering angle to ±63° via mutual coupling. The obtained results demonstrate a good agreement between the simulation and measurement and have a huge potential for development of X‐band radar

A Wideband Reconfigurable Folded Planar Dipole Using MEMS And Hybrid Polymeric Substrates

A wideband reconfigurable folded planar dipole using hybrid polymeric substrates is proposed. Artificial Magnetic Conductor (AMC) is a periodic structure composed of rectangular patches integrated with Jerusalem Cross (JSC) slots and being located in between two substrates. The Perfect Magnetic Conductor (PMC)-like behaviour of the AMC structure enabled the printed folded dipole to be placed near to the proposed structure, resulting in a low-profile antenna with 5.11 dB gain operating at 9.41 GHz. The combined use of the polymeric substrate and the proposed AMC resulted in a 1 GHz of bandwidth. The proposed antenna is capable in beam steering on the xz-plane via the integration of radio frequency (RF) MEMS switches placed on the antenna feeding transmission line. Simulations and measurements show a satisfactory agreement, with a beam steering capability at least 30, bandwidth of 1 GHz and maximum gain of 5.11 dB

A low profile, dual-band, dual polarized antenna for indoor/outdoor wearable application

A planar, low-profile, dual-band and dual-polarized antenna on a semi-flex substrate is proposed in this paper. The antenna is fabricated on Rogers substrate with a thickness of 3.04 mm and sized at 70.4×76.14×3.11 mm3 (0.37λ0 ×0.40λ0 ×0.016λ0) only. The circular polarization property is enabled in the global navigation satellite system (GNSS) L1/E1 (lower) band by introducing a complementary split ring resonator on the antenna patch. Meanwhile, the antenna operates in the second (upper) 2.45 GHz WLAN band is enabled by etching a U-shaped slot on its ground plane. This simultaneous, dual-band and dual-polarized operation enables the proposed antenna to be applied in the indoor/outdoor wearable application. To isolate the antenna against the influence of the human body, a multiband artificial magnetic conductor (AMC) plane is added on the reverse side of the dual-band radiator. Comparison of the antenna without AMC in free space and when evaluated on the chest of a human body backed by AMC showed improved gain; from 3–5.1 dBi in the lower band, and from 1.53–5.03 dBi in the upper band. Besides that, the front-to-back ratio of the AMC backed monopole antenna also improved from 11–21.88 dB and from 2.5–24.5 dB in the GNSS and WLAN bands, respectively. Next, the specific absorption rate (SAR) of the monopole antenna with and without the AMC plane is assessed. Evaluation results indicate that the maximum SAR value decreased by up to 89.45 % in comparison with the antenna without AMC in the lower band. This indicates the effectiveness of the AMC array in increasing gain and FBR, besides reducing EM absorption in the human body

Performance evaluation of 2-port MIMO LTE-U terminal antenna with user’s hand effect

This paper presents the performance evaluation of 2-port MIMO antenna for LTE-U sub 6 GHz band. The evaluation focuses on the effect of user’s hand in a uniform environment and the analysis were carried out on simulation and measurement data of antenna ports. Results show that the highest performance of the design is on the frequency range from 4.5 GHz to 5.5 GHz, and the ports have low envelope correlation coefficient (ECC) less than 0.16 in both cases of without and with user’s hand. However, the presence of the user’s hand reduces mean effective gain (MEG) of ports and diversity combining gain by more than 1.6 dB compared with no-hand case. The multiplexing efficiency is around 81% and reduced by the presence of the user’s hand to 55%. Despite this reduction; the design shows high spatial multiplexing capability in both cases. The capacity carried by the second transmission eigenmode is about 39% from the total capacity under water-filling algorithm transmit power allocation

Study of multiple antennas with defected ground slot for low-band LTE application

This study is focused on highly coupled multiple antennas with defected ground slot techniques. Two Printed Inverted-F Antenna (PIFA) are positioned at the top edge of chassis symmetrically. Both antennas are operating at low-band Long-Term Evolution (LTE) with center frequency, 829MHz. Rectangular defected ground slot is implemented to reduce the coupling effect between the antennas on the ground plane of the small chassis. Parameter study of the rectangular defected ground slot is studied with different width, W and length, L. Furthermore, the optimized dimensions of rectangular defected ground slot, W and L are simulated and presented. The optimized defected ground slot reduced the mutual coupling up to -4.5 dB. The envelope correlation coefficient (ECC) achieved less than 0.5. The ground plane of the multiple antenna structure has been further investigated by introducing another slot with a gap of 1mm between them. The achieved result is not significant in term of S-parameter and ECC compared to single defected ground slot

Bandwidth and gain enhancement of a circular microstrip antenna using a DNG split ring resonator radome

This paper present the design of a circular patch microstrip antenna with enhancement in terms of bandwidth and gain using a dielectric double negative (DNG) split ring metamaterial radome. This radome is positioned on top of the CP antenna operating from 5.2 GHz to 6.4 GHz. The metamaterial radome comprises of two alternate split rings of negative permittivity, permeability and refractive index. The circular microstrip antenna bandwidth of 430 MHz has been realized by the presence of DNG metamaterial radome compared to 220 MHz without the radome. The gain has been increased as well from 1.84 dBi to 3.87 dBi

Miniaturized dual-band antenna array with double-negative (DNG) metamaterial for wireless applications

A miniaturized dual-band antenna array using a negative index metamaterial is presented for WiMAX, LTE, and WLAN applications. This left-handed metamaterial plane is located behind the antenna array, and its unit cell is a combination of split-ring resonator, square electric ring resonator, and rectangular electrical coupled resonator. This enables the achievement of a metamaterial structure exhibiting both negative permittivity and permeability, which results in antenna size miniaturization, efficiency, and gain enhancement. Moreover, the proposed metamaterial antenna has realized dual-band operating frequencies compared to a single frequency for normal antenna. The measured reflection coefficient (S11) shows a 50.25% bandwidth in the lower band (from 2.119 to 3.058 GHz) and 4.27% in the upper band (from 5.058 to 5.276 GHz). Radiation efficiency obtained in the lower and upper band are \u3e95 and 80%, respectively

Textile-based flexible linear-to-circular polarizing surface for s-band pico-satellites

This paper presents a single layered textile-based flexible linear-to-circular polarizing surface. The proposed structure is designed based on a rectangular ring structure for CubeSat application in the S-band. Each unit cell is sized at 0.35λ×0.33λ×0.2λ for operation centered at 2.2 GHz. This unit cell is then multiplied into a 9x10 array to form the polarizing surface. It features a 3 dB axial ratio bandwidth (ARBW) of 34.73%, with a minimum AR of 0.28 dB. Besides that, it also offers a 90 % conversion efficiency bandwidth of up to 47.34%. The proposed structure’s performance is validated by placing it in front of a patch antenna operating at 2.2 GHz. The antenna performance indicated an increase in terms of gain from 3.14 dBi to 7.33 dBi when integrated with the polarizing surface, besides successfully converting linearly-polarized waves to circularly-polarized