Metamaterial Inspired Frequency Reconfigurable Antenna for Sub 6GHz Applications

In this paper, we propose a compact frequency reconfigurable (FR) multiple-inputmultiple-output (MIMO) antenna in a overall size of 51 × 53 × 0.8 mms. The MIMO antenna consists of two symmetrical FR ones using two PIN diodes on ground plane and has a simple bias circuit without capacitor. By switching the PIN diodes, the FR MIMO antenna can operates in the three states covering bands of tte universal mobile telecommunication system (UMTS), of the long-term-evolution (LTE) at 2.3 GHz, and 2.6 GHz with peak gains of 1.55, 1.81, and 0.87 dBi, respectively. A slot is added on the ground plane to achieve a low mutual coupling between antenna elements of less than −20 dB in all operating bands. The process of antenna design as well as calculating desired frequency bands are presented in detail. The antenna is fabricated on FR4 substrate and the simulated S-parameter results of the antenna are in good agreement with measurement results.

Small printed antennas suffer from low efficiency. Low profile efficient antennas are crucial in the development of commercial compact 5G communication and Internet of things (IOT) systems. The communication, IOT and biomedical industries have been in rapid growth in recent years. It is important to develop efficient high gain compact antennas for 5G communication and IOT systems. Metamaterials and fractal structures may be used to improve the efficiency of compact printed antennas. In this chapter metamaterial antennas will be presented. Metamaterial technology is used to design small wideband wearable antennas with high efficiency. Design considerations and the computed and measured results of printed metamaterial antennas with high efficiency are presented in this chapter. The proposed antenna may be used in communication and medical systems. The antennas’ S11 results for different positions on the human body are presented in this chapter. The gain and directivity of the patch antenna with split ring resonator (SRR) is higher by 2.5 dB than the patch antenna without SRR. The resonant frequency of the antenna with SRR on human body is shifted by 3%.

A highly compact (volume of only 8 × 8 × 1.6 = 102mm3) metamaterial antenna operating at 26 GHz (5G) and 33.2 GHz (higher satellite band) is presented. The structure of antenna is embedded with a symmetrical rectangular radiator and a metamaterial Rectangular Split Ring Resonator (RSRR). The symmetrical rectangular radiator controls the band at 26 GHz and metamaterial RSRR controls the band at 33.2 GHz. The antenna has S 11 <-10dB bandwidth of 1600 MHz, centered at 26 GHz and 600 MHz centered at 33.2 GHz. Highly compact size, good gain and radiation efficiency are obtained at the targeted 5G and higher satellite band frequencies.

PurposeIn wireless communication system, use of multiple antennas for different requirements of system will increase the system complexity. However, reconfigurable antenna is maximizing the connectivity to cover different wireless services that operate different frequency range. Pattern reconfigurable antenna can improve security, avoid noise and save energy. Due to their compactness and better performance at different applications, reconfigurable antennas are very popular among the researchers. The purpose of this work, is to propose a novel design of S-shaped antenna with frequency and pattern diversity. The pattern and frequency reconfiguration are controlled via ON/OFF states of the PIN diode.Design/methodology/approachThe geometrical structure of the proposed antenna dimension is 18 × 18 × 0.787 mm3 with εr = 2.2 dielectric constant. Three S-shaped patches are connected to a ring patch through PIN diodes. The approximate circumference of ring patch is 18.84 mm and length of patch is 5 mm, so approximate length of radiating patch is 14.42 mm and effective dielectric constant is 1.93. Conductor backed coplanar waveguide (CPW) is used for feeding. The proposed antenna is designed and simulated on CST microwave studio and fabricated using photolithography process. Measurements have been done in anechoic chamber.FindingsAntenna shows the dual band operation at 2.1 and 3.4 GHz frequency. The first band remains constant at 2.1 GHz resonant frequency and 200–400 MHz impedance bandwidth. Second band is switched at seven different resonant frequencies as 3.14, 3.45, 3.46, 3.68, 3.69, 3.83 and 3.86 GHz with switching of the diodes. The −10 dB bandwidth is more than 1.4 GHz.Research limitations/implicationsPattern reconfigurability can be achieved using mechanical movement of antenna easily but it is not a reliable approach for planar antennas. Electronic switching method is used in proposed antenna. Antenna size is very small so fabrication is very crucial task. Measured results are deviated from simulation results due to fabrication error and effect of leads of diodes, connecting wires and battery.Practical implicationsThe reconfiguration of the proposed antenna is controlled via ON/OFF states of the three PIN diodes. The lower band of 2.1 GHz is fixed, while second band is switched at five different resonant frequencies as 3.27, 3.41, 3.45, 3.55 and 3.88 GHz, with switching of the PIN diodes with all state of diodes and exhibit pattern reconfigurability at 2.1 GHz frequency. At second band center frequency is significantly changed with state of diodes and at 3.4 GHz pattern is also changed with state of diodes, hence antenna exhibits frequency and pattern reconfigurability.Originality/valueA novel design of pattern and frequency reconfigurable antenna is proposed. Here, work is divided into two parts: first is frequency reconfiguration and second is radiation pattern reconfiguration. PIN diodes as switch are used to select the frequency band and reconfigure the radiation pattern. This proposed antenna design is novel dual band frequency and pattern reconfigurable antenna. It resonates at two distinct frequencies, i.e. 2.1 and 3.4 GHz, and has a pattern tilt from 0° to 355°. The conductor backed CPW feed technique is used for impedance matching.

This paper presents the design and analysis of a reconfigurable microstrip slot antenna using RF PIN diodes as switching device for S and C band. Here pattern and frequency reconfigurable microstrip antenna is designed by changing the slot length on ground plane through six MPP4203 PIN Diodes. These six PIN diodes are used to electrically connect and disconnect the slot to alter the total slot length 76 mm in x axis and 56 mm in y axis. Here three switches are positioned in slot which is cut along the x-axis and another three switches are positioned in the slot along the y-axis. The analysis of reconfigurable antenna using PIN diode is done using the simulation performed on Ansys HFSS. The pattern and frequency reconfigurability of proposed antenna is analyzed for S (2–4 GHz) and C band (4–6 GHz) in terms of return loss and radiation pattern. The microstrip antenna design shows the pattern and frequency reconfigurability at 11 resonating frequencies. The proposed reconfigurable antenna is capable to resonate at three resonating frequencies (2.2, 2.3, and 2.4 GHz) in S band and 8 resonating frequencies (5.7, 5.8, 5.9, 6, 6.1, 6.3, 6.4, and 6.5 GHz) in C band. The simulated radiation patterns at various resonating frequencies shows pattern reconfigurability with acceptable gain in xz and yz plane of microstrip patch antenna. Furthermore the re-configurable antenna reduced the front end system's size and offers pre-filtering at the receiver. The proposed microstrip patch slot antenna is quite suited to be integrated with WLAN and Bluetooth devices with less structure complexity.

Nowadays, a novel compact frequency and polarization reconfigurable microstrip antenna is an engaging alternative to fit CR (cognitive radio) system engrossment. In this chapter, the proposed design has a straightforward and effortless construction. A simple rectangular microstrip patch cut by slot and the patch interconnect with four L-shaped strip lines. By enabling/disabling (ON/OFF) the (HPND4005) PIN diodes, the antenna operates at different frequency bands like 7.4, 9.1, 10.5, 10.9, and 11.4 GHz. The antenna performance parameters, such as VSWR, gain, radiation pattern, return loss, and surface current, are also presented. The proposed antenna design used FR4 substrate with dielectric constant εr = 4.4. Antenna dimensions are (35.9×58.94×1.6) mm. The designed antenna structure can be used for applications such as satellite communications and cognitive radio.KeywordsAxial ratioCognitive radioFrequency reconfigurationMicrostrip patchPolarization reconfiguration

Sensors such as phased array radars play a crucial role in public safety. They are unavoidable for surveillance, threat identification and post-disaster management. However, different scenarios impose immensely diverse requirements for these systems. Phased array systems occupy a large space. In addition, if different antenna systems are needed for each function, the space required can be considerably large. For transportable platforms, such as ships and aircrafts, space and weight are critical parameters. Therefore, reconfigurable multi-band antennas are very attractive solutions for future multi-function sensor systems. Within this research work three different approaches are investigated to realize antennas for reconfigurable phased arrays. Wideband antenna designs constitute the first approach. Integrating this type of antennas with frequency selective filters provide the opportunity for fine tuning within one radar band. The wideband operation of the antenna is achieved by the blind-via feeding section and the quasi electric-magnetic radiating structure. The second approach involves the design of an antenna element with p-I-n diode switches. The switches are used to alter the antenna structure and thereby the operating frequency. Measured results verified the frequency reconfigurable capability of the antenna within L/S radar bands with frequency ratio more than 2:1. The planar structure, the back feeding mechanism, the compact size and the simple bias network made the proposed antenna suitable for array applications. The large frequency ratio and its usability in phased array applications made the design novel. Furthermore, for these frequency reconfigurable elements, a unique multi-scale array structure is introduced which can assure wide angle scanning for both frequency bands. The advantage of this novel array configuration is twofold: reduce the mutual couplings in the lower band, and increase the scanning volume for the higher band. A planar array demonstrator validated the proposed concept. In the third approach the operational band of an antenna is tuned by variable-impedance matching. In this study, the standard 50 ? matching is avoided and many advantages of variable-impedance matching are demonstrated. First, the principle is verified by tuning the frequency band of a microstrip antenna by an input-impedance tuneable CMOS RF-frontend. In the second design a novel dual-band E-slot antenna, with 2.5:1 frequency ratio, was designed. By changing the input-impedance the operating frequency of the antenna can be switched from L- to S-band. Variable-impedance matching provides few other advantages to phased array antennas. A scan-angle dependent impedance matching will assure low reflection coefficients for the entire scanning volume. On the other hand, it will reduce interfering and jamming signals coming from adjacent angles. The outcomes of this research work have led to solid understanding of how we can realize frequency reconfigurable antennas for adaptive phased arrays. The results will be particularly valuable in developing future narrow or wide beam radar systems with frequency reconfiguration and angular filtering capabilities.

In this paper, the design of compact, wideband and tunable antenna is presented. The proposed antenna is consisting of a U-slot, stacked, shorted rectangular patch and complementary split ring resonator on ground plane. The antenna utilizes the shorted wall, stacked structure and complementary split ring resonator for size reduction and wideband characteristics. The antenna tuning is realized by using PIN diode. By making PIN diode ON and OFF, antenna may be configured to wideband or dual band mode. Both the simulated and experimental results are presented. The proposed antenna provides a good radiation pattern and a relatively constant gain over entire band of frequency. The proposed antenna achieves a 15.38 % size reduction with wideband characteristics.

This paper highlights the proposed design for a dual band Frequency Reconfigurable Monopole antenna fed through a 50Ω line feed over the Rogers substrate for GSM 900 and Wi- Max applications. The novelty of the proposed work lies in using two perpendicular strips loaded with Rectangular Complementary Split Ring Resonator in the Ground plane. The Monopole antenna is proposed to tune between two frequencies of 0.9GHz and 3.5GHz.The structure has been proposed on a Rogers's substrate of permittivity 2.2 with a thickness of 1.6mm.The radiating structure resulted in a Gain of 6.7dBi,8.429dBi,a Bandwidth of 80.5MHz, 144MHz for the lower and the upper frequency bands respectively. The structure resulted in a omnidirectional radiation pattern in the Wi-Max band.

This paper presents the design of a rectangular patch antenna with compound reconfigurability in terms of operating frequency and radiation pattern using only four PIN diodes. Two PIN diodes namely, PD1 and PD2, are implanted on a rectangular slot of the driven patch for frequency reconfiguration. While other two PIN diodes PD3 and PD4, are uniquely arranged with shorting posts between parasitic elements and ground, perform the pattern reconfiguration operation. Switching of PD1 and PD2 changes the effective electrical length of driven patch for four different measured resonant frequencies at 3.35, 4.02, 4.12 and 5.12 GHz. Moreover, ON/OFF states of PD3 and PD4 alter the function of parasitic elements between director and reflector to achieve H-plane pattern reconfiguration in all reconfigurable operating frequencies. Measured tilt angles at 3.35, 4.02, 4.12 and 5.12 GHz bands are (−40°, 0°) (+30°, −42°, 0°) (+40°, −40°, 0°) and (+36°, −43°) respectively. Measured results of reflection coefficient and radiation pattern are in good agreement with the simulated results, which validates the frequency and pattern reconfigurable performances of the antenna. The proposed antenna can be used for various C band wireless applications such as sub-6-GHz 5G (3.3 GHz, 4 GHz), and WLAN (5.2 GHz).

A frequency reconfigurable ultra-wide band antenna with dual notch bands is proposed in this paper. PIN diodes are located on ultra-wide band monopole antenna and are investigated for frequency reconfigurable characteristic of the proposed antenna. Multi-bands and narrow bands have been achieved by different combinations. Proposed antenna is fabricated on FR-4 substrate of dimensions 37 x 40 x 0.8mm3. For the successful combinations, antenna performance parameters like S11 characteristics, surface current distribution, peak gain, radiation efficiency and 2D radiation patterns are analyzed and illustrated in the paper. Peak gain of 4.83dB is obtained in operating band for D1, D2= 0, 1 combination. Radiation efficiency is not less than 70% in the entire operating bands. Results are analyzed experimentally for validating proposed antenna. Simulation based results and measured results are in good agreement.

In this paper, metamaterial superstrate is proposed to enhance the performance parameters of conventional rectangular microstrip patch antenna. The metamaterial is designed using proposed diagonally connected square split ring resonator (DC SSRR). The designed DCS SRR shows the negative values of refractive index for broadband frequency band, 5.0 GHz to 12 GHz. Use of metamaterial superstrate on conventional rectangular microstrip antenna improves the return loss by 18 dB and enhances the gain, bandwidth and radiation efficiency by 1.2 dBi, 28 MHz and 17.5% respectively. The permittivity, permeability and refractive index of metamaterial are numerically computed using MATLAB. All performance parameters of antenna and S-parameters of DC SSRR are obtained using commercially available full wave electromagnetic simulator HFSS based on finite element method and verified by measured results. Good agreement is found between simulated and measured results.

This paper introduces the design of a new frequency-reconfigurable ultra-high frequency radio frequency identification (UHF RFID) antenna, demonstrating an innovative approach that enables dynamic adjustment of its resonance frequency. The proposed antenna design features a central dipole structure, enhanced by two hexagonal split-ring resonators (H-SRR) at each end. A T-match network is integrated into the center of the dipole, which is essential for achieving impedance matching between the antenna and the Alien Gen2 H4 RFID microchip. The antenna is designed using a Rogers 4350B substrate, a high-performance dielectric material ideal for RFID applications. With dimensions of 68×32.6×1.524 mm3, the compact antenna maintains full UHF band (860 MHz to 930 MHz) coverage compliant with International Telecommunications Union (ITU) RFID standards. This ensures that the antenna can be used in different regions around the world, offering broad compatibility with various RFID systems. The antenna's frequency reconfigurability is achieved through the integration of localized capacitors with variable values, which plays a key role in enabling precise adjustments to the antenna's center frequency across the entire UHF band. Extensive simulation results validate the effectiveness of this reconfigurable design, demonstrating that the antenna can dynamically adjust its frequency while maintaining excellent performance metrics, including impedance matching, radiation efficiency, and bandwidth. This makes the proposed antenna an ideal choice for modern RFID applications.

A triangular patch frequency reconfigurable an-tenna is designed for wireless and UWB applications. Frequency reconfigurability is achieved by inserting PIN diodes between the radiating patch and the three parasitic stubs. The gained frequencies at 2.1 – 2.6 GHz and 2.7 – 7.3 GHz are propagated by incorporating patches around the radiating patch and placing the diodes in between the PIN patches. The multi-band operation is accomplished using the parasitic patches and PIN diodes. The designed antenna can strain the frequency from ultra-wideband to multi-band. Gain and Radiation Efficiency are improved in the perspective design. Along with the wireless applications, the designed antenna is covering the lower frequencies of C- band. Co and cross polarizations are refined in both E and H plane.

A compact wideband and high gain GRIN metamaterial lens antenna system suitable for C, X, Ku band application