High Isolation by Small Dual‐Polarized Antenna With Dual Vertical Split‐Ring Resonators

A wideband highly isolated multiple-input-multiple-output patch antenna with an artificial magnetic conductor (AMC) ground plane is proposed in this letter. The antenna, which is rotationally symmetrical, is constructed by V-shaped patches coupled by a bowtie dipole. The bowtie dipole and the V-shaped parasitic patches produce two resonant modes that are coupled together. Therefore, a wide impedance bandwidth is obtained. Thanks to the orthogonal feeding and the rotationally symmetrical geometry, the antenna exhibits high port isolation as well as symmetrical radiation patterns with a compact size of 40 × 40 × 1.524 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . By placing an AMC ground plane with a distance of 10.5 mm below the radiating element, the antenna can achieve a unidirectional high gain with a lower height of the profile compared to that with perfect electrical conductor ground. Measured results show the antenna has an impedance bandwidth of 31.0% (3.0-4.1 GHz) with port isolation better than 25 dB. The peak gain can reach 7.1 dBi with stable and symmetrical radiation patterns.

We propose a low-cost, dual band (2.4–5.2 GHz) and dual band (2.4–5.8 GHz) MIMO antennas by using two identical T shaped antenna with high isolation. MIMO is a technique that is used a multiple number of antennas as a transmitter and a receiver. Using artificial magnetic conductor as a reflector made our antenna low profile and high isolated. A dual-band MIMO antenna with high isolation by using artificial magnetic conductor (AMC) is proposed.

A metamaterial approach to wideband radar cross section reduction that is thin, low-cost and doesn't dictate object shaping is presented in work from Iran. The approach uses principles potentially applicable to infrared and visible light as well as radar. The wideband RCS reducing surface is produced on a commercial high-frequency circuit substrate using conventional printed circuit manufacturing techniques Reducing an object's detectability to radar systems is now a well established priority for military applications, most famously in aircraft applications. ‘Stealth’ aircraft that were once well kept secrets are now a familiar concept to the general public and even fly in air shows. The radar cross section (RCS) of an object is essentially a measure of how detectable an object is to radar systems and so reducing an object's RCS is the basic goal of radar focused ‘stealth’ technologies. There are three main approaches to reducing RCS; radar absorbing material (RAM), object shaping and reflected wave cancelling by object coating. RAM materials, as the name suggests, are designed to reduce radar reflections back to the detector by absorbing the electromagnetic energy transmitted by the radar system, converting it into heat. However, they can be bulky and high maintenance. Object shaping works by shaping the surface of the object to minimise reflections of the radar waves back to the radar system, instead reflecting them in other directions. The obvious disadvantage to this approach is that it dictates the shape of the object, which can compromise the performance of the object for its primary purpose. For example, above all an aircraft must be shaped to enable it to fly, an aircraft that is very hard to detect but cannot take off is of no use to anyone. The work reported in this issue, by researchers at Iran University of Science and Technology (IUST) uses the third approach, in which a surface coating reflects the radar waves in such a way as to reduce the amount of radar energy that returns to the detector. This approach is low profile, low bulk and doesn't dictate the shape of the object. In the IUST team's work it can also be cheaply and simply manufactured using printed circuit board manufacturing techniques. Their proposed structure consist of a chessboard arrangement of two different artificial magnetic conductor (AMC) unit cell patterns, each of which reflects the radar waves differently. The key difference in the reflections is a 180° phase shift, which causes the reflections from the two different AMC cell types to interfere destructively and so significantly reduces the useful energy returned to the radar system's detector. “Since radar systems usually send out a short pulse signal in the time domain, wide bandwidth of the RCS reducer is necessary. The proposed AMC structure achieves a RCS reduction over a very wide bandwidth, about 85%,” said Dr Seid Hasan Sedighy, one of the IUST researchers on this project. The wide bandwidth achieved is possible because the critical 180° phase difference in the reflections is produced by the AMC unit cells over a wide frequency range, from 9.4 GHz to 23.28 GHz, providing 10 dB RCS reduction in that range. The peak RCS reduction is in excess of 40 dB, at 15 GHz. Printed circuit manufacturing techniques were used to create the AMC patterns on a commercial high-frequency circuit substrate, providing a low-cost manufacturing method. As flexible circuit board technologies are now available and continue to develop, this AMC-based, effective and relatively cheap approach to RCS reductions could be applied to arbitrary shapes. AMCs are metamaterial structures that behave as perfect magnetic conductors in a limited range of frequencies. The two unit cell AMC patterns used in this work are an arrangement of ‘E’ shapes and saltire arrows. The patterns were optimised to achieve the desired 180° phase difference in their reflections by simulation before being confirmed by experiment. The RCS reducer consists of a chessboard pattern of AMC patches using two different AMC unit cell designs, which produce reflections 180° out of phase with each other. The resulting destructive interference provides the intended RCS reduction The principles of AMCs and using destructive interference to reduce reflected energy are of course applicable to other frequencies of the EM spectrum, not just the band used for radar. This means that similar effects could be achievable in very different frequencies if the structures can be manufactured. Dr Sedighy expects this to lead to developments closer to photonic frequencies “It seems that this design approach will develop in the other frequency bands such as visible and infrared frequencies, which have many civil and military applications.”

This work studies the integration of a semicircular shaped array antenna into an Artificial Magnetic Conductor (AMC) which resonate at the desired operating frequency of 9.41 GHz. The proposed AMC performs as a high impedance surface with a high permeability (approximately 7.08) at 9.41 GHz, with a perfect magnetic conductor characteristic. As result, the AMC is able to be stacked adjacent to the semicircular shaped. The simulation results show that the AMC has successfully enhanced the gain and efficiency of the antenna to 9.55 dB and 97% respectively compared to 8.44 dB and 96% without AMC. Besides that, a slight bandwidth improvement, from 395 MHz to 398 MHz can be observed with the AMC. Both simulated and measured results show a good agreement in term of reflection coefficients and radiation patterns.

A dual-frequency substrate integrated waveguide (SIW) cavity backed slot antenna over an Artificial Magnetic Conductor(AMC) is presented in this paper. The Artificial Magnetic Conductor is designed as a dual-band structure having an array of unit cells and operates at 7.5GHz and 12.8GHz. A circle and crisscross slot into a square metallic patch as a back-plane. By comparing the performance of the antenna loaded with AMC and without AMC. It is found that the gain of the antenna loaded with the AMC increase is obviously. The distance between the dual-frequency antenna and the AMC is $0.12\lambda$ , Improvements of front lobe to back lobe ratio are achieved as a result of using dual resonant AMC which has surface wave suppression characteristic. The simulated results show that the combination of the AMC reflector and the antenna provide directional properties at both frequency bands.

Purpose Planar periodic metallic arrays behave as artificial magnetic conductor (AMC) surfaces when placed on a grounded dielectric substrate, and they introduce a zero-degree reflection phase shift to incident waves. The antenna designers have new challenges while designing the AMC structure. The steps followed in designing the structure are as follows: 1) Designing the antenna, aimed to operate at millimetric wave frequencies, (2) Designing the AMC at desired frequencies, (3) Integrating the antenna design and AMC to resonate at millimetric wave frequencies and (4) Validate the output parameters of the antenna to be suitable for Internet of Things (IoT) applications. Design/methodology/approach The antenna is integrated with artificial material known as high impedance surface (HIS) for performance enhancement. A miniaturized, multiband, enhanced gain, AMC-integrated CPW-fed antenna is proposed and aimed to operate at millimetric wave frequencies, which is most suitable for IoT applications. The developed antenna operates at an extremely high range (30–300 GHz), i.e. from 40 to 60 GHz with the return loss values at lesser than −20 dB, and gain is greater than 10. The antenna is developed and simulated by using HFSS software. Findings An extensive research study has been carried out to develop a low profile, high gain and optimized antenna. The first two steps are separately designing the antenna and the AMC unit cell at the desired frequencies. The third step is finding the antenna or AMC radiating parts responsible for each resonant frequency by analysing the surface current distribution. CPW fed along with AMC integration has made the antenna feasible to achieve the extremely high frequency (EHF) range, i.e. 40–60 GHz, which is highly adoptable in IoT applications. Originality/value The result represented that the developed antenna is resonating at EHF rank with high gain and good imped matching when it is being compared with the previous models and has only CPW fed without having AMC structure integration. It is evident that the antenna which has only CPW fed has resonated at lower frequency than EHF range and justified output characteristics. But when it is embedded with the AMC structure, it resonates at the EHF range, which makes the antenna highly suitable for IoT applications, with more accuracy and high data rate possibility.

This paper presents a compact, low‐profile, and wideband two‐arm monopole antenna tailored to operate efficiently within the 3.7–7.3 GHz frequency spectrum. The monopole antenna is traditionally known for its omnidirectional radiation pattern and relatively low gain. To enhance its performance, this design integrates the monopole with an artificial magnetic conductor (AMC). The AMC is configured as a 3 × 3 array of specially modified square unit cells, covering a surface area of 9 × 9 cm. The antenna is positioned 1.7 cm above the AMC surface, a strategic placement that significantly enhances gain across the entire frequency range. In this configuration, the antenna's gain is markedly improved, increasing from an initial range of 1.5–3.25 dBi to an enhanced 4.6–8.5 dBi. Impedance matching is evaluated for both configurations, demonstrating consistent wideband performance. Analysis of the radiation patterns indicates that the monopole maintains an omnidirectional pattern without the AMC but shifts to more directive beams when the AMC is integrated. This combination results in a radiation efficiency of approximately 98% across the operating frequency band. Prototypes of the antenna and AMC were fabricated using the Rogers RO4003C substrate, which has a dielectric constant of , a loss tangent of tan δ = 0.0027, and a thickness of 1.52 mm. Experimental testing of these prototypes closely matched the simulation data, verifying the accuracy and effectiveness of the design. This study not only confirms the potential of the two‐arm monopole enhanced with AMC for high‐gain, wideband applications but also demonstrates its viability through rigorous simulation and practical experimentation. The results suggest that this antenna system is well‐suited for modern communication systems that require efficient, wideband, and high‐gain performance within the specified frequency range.

This paper presents a microstrip patch antenna operated at the fifth generation (5G) frequency range, which is at 3.5 GHz. To enhance the performance of the proposed antenna, an Artificial Magnetic Conductor (AMC) structure is implemented into the design. The 1x3 AMC is sandwiched between two FR-4 substrates and the performance of the proposed antenna is compared with the antenna without AMC structure. The simulated results prove that the proposed antenna offers better reflection coefficient with -50.45 dB compared to only -15.55 dB for the conventional antenna. Wider bandwidth is also achieved with 427 MHz of frequency bandwidth as opposed to only 135 MHz for the antenna without AMC. Besides that, the integration of AMC enhances the gain of the antenna when 3.7 dBi is achieved in contrast to only 3.21 dBi for the conventional antenna. Moreover, the efficiency of the antenna with AMC is also improved up to 68.54%. Furthermore, the ability to shrink 52.23% of the size of the antenna without AMC making it very favorable to be applied in 5G bands.

SummaryA low‐profile eight‐element printed dipole antenna (PDA) array backed by broadband rhomboid artificial magnetic conductor (AMC) is introduced for wireless communication systems. By loading a 4 × 27 AMC reflector into the eight‐element array of PDA, a low‐profile wideband structure with enhanced radiation properties is achieved. The measured S parameters show the broad bandwidth from 4.75 to 7.05 GHz in C‐band with enhanced gains of eight elements (more than 8 dBi) and the suitable isolation between the array elements of more than 23 dB for multi‐input multi‐output (MIMO) systems. The suggested PDA with a pair of the microstrip meandered folded poles excited by an E‐shaped microstrip feedline expands the bandwidth in the range of 5.85–6.95 GHz (S11 ≤ −10 dB). The novel AMC unit cell is realized based on the recognized method as rhomboid coupled parasitic patches. The rhomboid AMC design operates at 6.26 GHz with an AMC bandwidth of 5.20–7.24 GHz (32.8%). Then, the suggested rhomboid AMC surface as a reflector of the antenna is inserted into the PDA to exhibit −10 dB measured impedance bandwidth from 4.94 to 6.93 GHz (more than 33%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 34%, enhanced gain up to 8 dBi, and excellent impedance matching (at least −20 dB) with directional radiation patterns.

We present a general method to design multiband absorber by replacing the ground plane in a conventional metamaterial absorber with an artificial magnetic conductor. Due to its unique property of in-phase reflection at some specific frequency, the artificial magnetic conductor is used to introduce new absorption in the operation band. Meanwhile, out of the in-phase reflection band, the original absorbing capability of the absorber is reserved. To demonstrate it, we design a metamaterial absorber comprising three layers which are grids patterned resistive frequency selective surface, dielectric layer and the ground plane respectively. With an appropriate design, the absorber performs an absorbing peak at about 10 GHz. Then, we utilize a single band artificial magnetic conductor at 6.25 GHz and a dual-band one at 6.27 GHz and 8.17 GHz, which are both lossy and comprised of patches array varying in periodic size with a thickness of 0.6 mm, to replace the ground plane in the metamaterial absorber separately. The reflectivity of these multiband absorbers are simulated, and experiments are carried out later. Experimental results agree well with the simulations. All results verified that the method presented at the beginning is effective. The results show that additional absorptions exist at the frequencies where microwaves are nearly reflected in phase on the artificial magnetic conductor. Meanwhile the original absorbing capability of the metamaterial absorber has been preserved mostly. Based on the artificial magnetic conductor, the multiband absorber performs better with an increasing absorption bandwidth from 8.5 GHz to 10 GHz compared to the metamaterial absorber.

A perfect magnetic conductor (PMC) surface reflects electromagnetic waves without any change in the electric field phase. However, there is no natural PMC material. Instead, artificial magnetic conductors (AMCs) have been developed, which mimic the behavior of PMCs at a particular frequency. There has been an extensive amount of research to increase the bandwidth in different AMC structures and to characterize its operating frequency. Here, the general reflection characteristics from an AMC surface is demonstrated. A theoretical upper limit for AMC bandwidth is derived in terms of AMC structural parameters and validated for different AMC structures. Finally the effects of AMC structural parameters on the operating frequency of an AMC are investigated.

This paper presents the performance of a microstrip monopole antenna with and without an Artificial Magnetic Conductor (AMC). The antenna and AMC structures are designed at 2.45 GHz using Rogers RO3003 and RT5880 respectively. The thickness of the substrate of the antenna is 1.52 mm and the permittivity are 3. For the AMC, the thickness and the permittivity of the substrate are 3.18 mm and 2.2. The designed antenna has a hexagonal shape, and it is grounded by 3x3 AMC array. From the simulated results, it is found that integrating the AMC structure to the printed monopole antenna was significantly improved the gain and directivity of the antenna. With the AMC, the achieved gain is 6.54 dB, which exhibited 3.68 dB of increment. This antenna has high gain, as it has both high radiation efficiency and directivity. Its directivity increased from 3.01 dBi to 7.14 dBi. The measured results are in align with the simulated results. The antenna still operate at the desired frequency. The recorded measured gain is 5.33 dB, with 20.3 dB return loss at 2.4 GHz. Thus, the design of the monopole antenna with the AMC is suitable as a RFID tag, because it can improve the RFID reading distance.

In this work, we designed a millimeter wave textile antenna for the 28 GHz band. This antenna was tested using textile materials placed over an artificial magnetic conductor (AMC). The prototype (antenna and AMC) was fabricated on polyester substrate with a thickness equal to 0.35 mm and a size of 16.8*14.4*1.84 mm3 only. To isolate the antenna from the human body, an artificial magnetic conductor (AMC) plane was added on the reverse side of the ground plane. The simulation results obtained by simulator CST present the electrical and radiation characteristics of the proposed antenna. The comparison of the antenna without AMC in free space and that backed by AMC showed that the latter performance is better. The proposed structure can be used in smart garments with minimized risk to human health.

A fold dipole slot antenna backed by artificial magnetic conductor (AMC) structure based on a standard 0.18 um CMOS process on chip application is firstly proposed in this paper. Conventional silicon antenna on chip (AoC) suffers from low radiation performance because the most electromagnetic energy is restricted in silicon substrate as surface wave for its high dielectric permittivity. The energy is dissipated as thermal for low resistivity of silicon substrate. AMC constructed by a periodic 6*6 square patch array is adopted as background to improve radiation performance of the proposed folded dipole slot AoC. Gain of the proposed AMC backed AoC is improved about 3.5 dB compared with that of the same AoC without AMC background.

A low-profile broadband dual-polarized antenna is investigated for base station applications. It consists of two orthogonal dipoles, fork-shaped feeding lines, an artificial magnetic conductor (AMC), and parasitic strips. By utilizing the Brillouin dispersion diagram, the AMC is designed as the antenna reflector. It has a wide in-phase reflection bandwidth of 54.7% (1.54–2.70 GHz) and a surface-wave bound range of 0–2.65 GHz. This design effectively reduces the antenna profile by over 50% compared to traditional antennas without an AMC. For demonstration, a prototype is fabricated for 2G/3G/LTE base station applications. Good agreement between the simulations and measurements is observed. The measured −10-dB impedance bandwidth of our antenna is 55.4% (1.58–2.79 GHz), with a stable gain of 9.5 dBi and a high isolation of more than 30 dB across the impedance passband. As a result, this antenna is an excellent candidate for miniaturized base station antenna applications.