Printed Antenna Structures Research Articles

Design of Novel Ultrabroadband Printed Antenna and Its Efficient Optimization Using Self-Adaptive Hybrid Differential Evolution Algorithm

A novel compact ultra-broadband-modified fork-shaped printed antenna is optimized efficiently by using a self-adaptive hybrid differential evolution (SHDE) algorithm. Firstly, a novel compact ultra-broadband-modified fork-shaped printed antenna structure is proposed. The antenna with more compact size consists of a modified fork-shaped radiator and a modified ground plane, which can cover a very wide operating frequency band. The antenna is fed by a step-shaped microstrip line, and the modified ground plane consists of some rectangular slots and an L-shaped stub. Then, the SHDE algorithm is used to determine structural dimensions of the proposed antenna, and the antenna’s performance is optimized while maintaining a cost-effective computation time. The optimized antenna with only 11.8 mm × 19.7 mm size covers -10 dB reflection coefficient bandwidth of 147.6% from 3.08 to 20.46 GHz. Finally, the antenna prototype is fabricated, and the measured results basically agree with the simulated ones. The proposed antenna can be viewed as an excellent candidate for realizing ultrabroadband transmission technology.

Narrowband Passive RF Tags for Frequency-Selective Harmonic Doppler Radar Tracking

A design for frequency-selective radio frequency (RF) harmonic tags for harmonic Doppler radar tracking is presented. Harmonic RF tags receive an incident microwave signal and generate a retransmitted signal at a harmonic of the incident frequency, typically the second harmonic. Since environmental backscatter occurs at the fundamental frequency, the second harmonic can be easier to detect. Typical harmonic tags operate over a reasonably wide fractional bandwidth, and thus to detect multiple tags within the same field of view, additional circuitry must generally be added to the tag to differentiate the responses. We propose a different approach based on frequency selectivity implemented by the tag antenna. Based on narrowband split-ring printed antennas, the tags accept incident signals over a specified narrow fractional bandwidth, after which the second harmonic is generated by a diode and retransmitted with a standard dipole antenna. The narrowband filtering occurs at the fundamental frequency antenna, and thus with tags designed at adjacent narrowband frequency channels, no additional circuitry is necessary to differentiate multiple tags. Fabricated tags achieved fractional bandwidths below 0.5% at carrier frequencies below 2.5 GHz while maintaining gains above 2 dBi. The construction of the tag is simple and low-cost, requiring only a single component (a diode) on a printed antenna structure. We demonstrate the feasibility of simultaneously measuring the time-varying harmonic Doppler signature of multiple tags in the field of view by experimentally verifying the frequency selectivity of tags in motion using a 2.4/4.8 GHz harmonic Doppler radar.

Design modifications and multilayer impact in the electronic parameters of printed graphene patch antenna

The stack antenna technique used to improve the antenna characteristics of the printed patch antenna structures. The method of stacking varies for each material. In this work we used graphene as the radiating material. The improvement in the parameters is achieved by edge truncation and ground plane optimization techniques. The main factor to affect the stacking is the curing temperature and the heat absorbing nature of the substrate and air gap between layers. In this work we have experimented and analysed the effect of multilayer stacking on printed antenna structures and its effect on the antenna performance. The antenna is designed for 2.45 GHz ISM Band applications and the gain is more than + 5 dB. In this paper we tried to replace the copper with multilayer graphene based printed structure.

An investigation of side lobe suppression in integrated printed antenna structures with 3D reflectors

The paper discusses the problem of side lobe suppression in the radiation pattern of printed antenna arrays with different 3D reflector surfaces. The antenna array of eight symmetrical pentagonal dipoles with corner reflectors of various angles is examined. All investigated antenna arrays are fed by the same feeding network of impedance transformers enabling necessary amplitude distribution. Considering the different reflector surfaces, the influence of parasitic radiation from feeding network on side lobe suppression is studied to prevent the reception of unwanted noise and to increase a gain.

Nano Antenna Array for Terahertz Detection

Infrared (IR) detectors have been fabricated consisting of antenna-coupled metal–oxide–metal diodes (ACMOMDs). These detectors were defined using electron beam lithography with shadow evaporation metal deposition. They are designed to be sensitive to the IR range and work at room temperature without cooling or biasing. In order to achieve large arrays of ACMOMDs, nanotransfer printing have been used to cover a large area with metal–oxide–metal (MOM) diodes and with antenna structures. The printed antenna structures consist of gold and aluminum and exhibit a low electrical resistivity. A large area array of MOM tunneling diodes with an ultrathin dielectric ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\sim}$</tex> </formula> 3.6-nm aluminum oxide) has also been fabricated via the transfer-printing process. The MOM diodes exhibit excellent tunneling characteristics. Both direct and Fowler–Nordheim tunneling has been observed over eight orders of magnitude in current density. Static device parameters have been extracted via kinetic Monte Carlo simulations and have confirmed the existence of a dipole layer at the aluminum/aluminum oxide interface of the printed tunneling diodes. The mechanical yield of the transfer-printing process for the MOM tunneling diodes is almost a 100%, confirming that transfer printing is suitable for large area effective fabrication of these quantum devices.

Small Printed Combined Electric-Magnetic Type Ultrawideband Antenna With Directive Radiation Characteristics

A small printed antenna structure is presented featuring directive radiation patterns over ultrawide frequency band without relying on large antenna dimensions. The antenna comprises virtually two antennas-one electric-type antenna and one magnetic-type antenna-excited simultaneously in close proximity via one feed point. This combination of radiated fields from different types of sources result in directive radiation patterns without increasing antenna sizes as typically observed in antennas using only one type of sources. Two printed prototypes of the combined antenna are fabricated and their measured VSWR and radiation gain pattern characteristics are discussed.

Compact dual concentric ring printed antennas

A novel small printed antenna structure is prepared that, depending on the excitation orientation, can yield low crosspolarised field generation or good quality circular polarisation (CP). The configuration consists of concentric shorted annular ring printed antennas. Each ring is loaded by a localised dielectric layer and can therefore be optimised to operate at a certain frequency, thereby enhancing the overall bandwidth of the antenna. Probe-fed configurations are investigated such that the appropriate feed network can be located below the radiating elements, thus minimising the footprint of the entire antenna. For a balanced feed configuration, the overall size of the antenna (including the ground plane and feed network) was 5/spl times/7/spl times/1.3 cm for operation centred at 2.1 GHz. The 10 dB return loss bandwidth was approximately 11.5% and the crosspolarisation levels were more than 15 dB below the co-polar patterns for both principle planes. The CP version was of similar size with an impedance bandwidth of 12.4% and a 3 dB axial ratio bandwidth of 16%.

Efficient wideband printed antennas on lithium niobate for OEICs

Printed antenna structures for integration with z-cut and x-cut LiNbO/sub 3/ based optoelectronic devices are presented. The designs are based on the hi-lo stacked patch element, which yields a high efficiency broadband antenna. Experimental verification of both printed antennas is given.

Active integrated antennas

Even with microwave techniques, however, signal losses in materials and decreased gain and power from solid-state devices become significant obstacles to creating low-cost, high-frequency wireless systems. Perhaps the most dramatic effect occurs when a circuit component becomes a significant fraction of a wavelength. At this point it may begin to function well as an antenna. For microwave and mm-wave signals, this can occur with circuits that are only centimetres in size. With conventional circuit techniques, this radiation may cause drastic signal losses, spurious coupling between circuit elements, and radio interference with other. However, with new techniques, it is possible to create circuits that use these effects to advantage. Known as active integrated antennas, these circuits have sparked interest as possible solutions to problems in designing the next-generation wireless systems. Active integrated antennas are a combination of solid-state devices and circuits with printed antenna structures. They comprise integrated radio-system elements that are fabricated using inexpensive printed-circuit techniques.

Computer‐aided analysis of microstrip antennas employing parasitic elements

AbstractThe moment method in the spectral domain is used to perform a computer‐aided analysis of printed antenna structures employing tuning stubs and electromagnetically coupled patches. Variation of the input VSWR versus frequency is obtained and the radiation patterns are plotted for various antenna configurations. Surface wave coupling effects are investigated. © 1993 John Wiley &amp; Sons, Inc.

Leaky and surface waves in anisotropic printed antenna structures

The behavior of the leaky- and surface-wave modes supported by single- and double-layered grounded anisotropic dielectric structures is investigated. Simple low-frequency and high-frequency asymptotic formulas are derived for the wavenumbers. The effects of dielectric anisotropy and losses on the cutoff frequency of the TM and TE surface waves and on the H-plane radiation pattern of a leaky-wave antenna are examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>