PEC Ground Research Articles

RCS Reduction of Waveguide Slot Antenna With Metamaterial Absorber

This communication investigates the application of metamaterial absorber (MA) to waveguide slot antenna to reduce its radar cross section (RCS). A novel ultra-thin MA is presented, and its absorbing characteristics and mechanism are analyzed. The PEC ground plane of waveguide slot antenna is covered by this MA. As compared with the slot antenna with a PEC ground plane, the simulation and experiment results demonstrate that the monostatic and bistatic RCS of waveguide slot antenna are reduced significantly, and the performance of antenna is preserved simultaneously.

Effect of Primary Source Location on Fabry-Perot Resonator Antenna with PEC or PMC Ground Plate

The radiation property of Fabry-Perot Resonator antennas made of PEC or PMC ground plate covered with a partially-reflecting surface effected by the primary source location is investigated theoretically, respectively. It is shown that the location of primary source affects the gain of Fabry-Perot Resonator antenna greatly, and the maximum of gain can be obtained when primary source is located at certain positions for these two types of ground plate. But the pattern bandwidth does not vary obviously with the source location, as long as the resonant condition on the height of Fabry-Perot cavity is satisfied. At the same time the normalized product of maxium of gain and its bandwidth act as a reasonable criterion for evaluating the performance of such kind of antenna, a function of reflection coefficient of partially reflective surface, trending to a certain limitation with increase of reflection coefficient is firstly proposed. Finally the simulated results of planar Fabry-Perot Resonator antenna are validated to have good agreement with the calculated theoretically, which is of great significance to antenna designing.

Low‐profile resonant cavity antenna based on an in‐phase metamaterial surface

AbstractA partially reflective metamaterial surface is designed to have in‐phase reflection property for the purpose of reducing the height of resonant cavity antennas. Since the reflection phase of the in‐phase is close to 0° at the operating band, the cavity height, that is, the distance between the metamaterial surface and the PEC ground, can be reduced from half wavelength to about a quarter wavelength, without using an artificial magnetic conductor as the ground. An example antenna is designed, fabricated, and measured to demonstrate the concept. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 731–733, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24134

Small EBG resonator high-gain antenna using in-phase highly-reflecting surface

A small EBG resonator antenna (1.62λ0×1.62λ0×λ0/4 in size) with specially-located PEC sidewalls to close the resonant cavity is proposed to achieve maximum directivity. An in-phase highly-reflecting surface is installed a quarter-wavelength above the PEC ground plane. For this small EBG resonator antenna, 13.5 dBi measured directivity and 11 dBi peak gain are obtained at 11.6 GHz.

Design of a broadband dipole in close proximity to an EBG ground plane

One of the known advantages of an electromagnetic bandgap (EBG) ground plane is the fact that a straight-wire dipole can be located parallel and in very close proximity to the ground plane. For such a structure and geometry, a reasonable impedance match to 50 n) can be achieved with more bandwidth than when the dipole is located in close proximity to a PEC ground plane. However, in addition to impedance, radiation-pattern properties must be considered when evaluating the antenna's overall performance and usable bandwidth. Here, we consider the performance properties of a folded bowtie dipole element in close proximity to an EBG ground plane, with emphasis on examining the bandwidth and pattern characteristics. We demonstrate that a dipole element can be designed to exhibit a matched input impedance over approximately a 1.4:1 bandwidth with respect to a 50 n characteristic impedance, when located in close proximity to the EBG ground plane. While the shape of the radiation pattern of the antenna remains relatively unchanged over much of this operating bandwidth, we show that the usable bandwidth of the antenna-EBG combination is limited to approximately 1.5:1, due to pattern degradation at both the lower and upper frequencies. Details of the design approach and feed structure used to match the impedance of the dipole to 50 fl are discussed. Finally, we show that with this element design, the reflection phase bandwidth of the EBG ground plan-e does not limit the matched impedance bandwidth of the antenna. A -portion of ,t ,he work detailed here was presented at the 2005 Antenna Applications Symposium.

Wideband low-profile circular polarized rectangular loop antenna over a mushroom-like EBG structure

In this paper, a wideband dual rectangular loop antenna over an EBG surface is proposed for low profile wireless applications. A low frequency mushroom-like EBG surface is used as the antenna ground plane. In comparison with a PEC ground plane, design of antenna above an EBG ground plane results in 60% reduction of the structure thickness. The investigated antenna is designed for circular polarization. It is shown that the axial ratio bandwidth (<3dB) and return loss bandwidth (<10dB) of the dual rectangular loop antenna above the designed EBG surface are 18% and 14%, respectively. The simulated and measured results are in good agreement.

APPLICATION OF ARTIFICIAL GROUND PLANES IN DUAL-BAND ORTHOGONALLY-POLARIZED LOW-PROFILE HIGH-GAIN PLANAR ANTENNA DESIGN

Application of artificial ground planes in design of compact cavity-resonance dual-band high-gain antennas is presented. The artificial ground plane consists of periodic strip grating on grounded dielectric slab. A code based on method of moment (MoM) is developed to analyze and design such artificial ground planes. The reflection parameters obtained using the MoM code are employed to characterize the surface impedance of the artificial ground plane for different incident angles and both TE and TM polarizations. Then, this impedance surface is used in transverse equivalent network (TEN) model of the cavity-resonance antenna with high-permittivity dielectric superstrate. Using TEN model radiation properties of such antennas are analyzed. Finally, the antenna with the compact size is designed to demonstrate the maximum directivity. An interesting characteristic of this antennas is that when the antenna ground plane acts as an artificial magnetic conductor the height of the antenna is almost reduced by a factor of two, while its directivity is increased by about 1 dB compared to the conventional antennas of this class having PEC ground plane.

Two‐dimensional efficient metamaterial‐inspired electrically‐small antenna

AbstractInexpensive, efficient, and electrically‐small antenna designs are presented, which are based on a two‐dimensional (2D) metamaterial‐inspired structure driven by an electrically‐small rectangular semiloop antenna that is coaxially‐fed through a finite PEC ground plane. Measured reflection coefficients showed a very good agreement with the simulated data, where the measured resonant frequency is only 0.5% different from the numerically predicted value. The proposed 2D antenna systems are linearly scalable with frequency, and predicted radiation characteristics of the antenna systems at 300, 430, and 1580 MHz are reported. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1669–1673, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22542

Compact Wideband UHF Patch Antenna on a Reactive Impedance Substrate

The goal of this letter is to design a compact, planar UHF antenna operating over the frequency range 420?450 MHz. A microstrip patch antenna is selected as the elementary radiating structure because it has a low profile and is simple to fabricate. Compact size and enhanced bandwidth are simultaneously achieved through the use of a reactive impedance surface (RIS) in place of a PEC ground plane. The inherently limited bandwidth of the patch is overcome by incorporating a U-shape resonant slot radiator within the patch area. The design, fabrication, and measurement results are presented. It is shown that a patch with a U-shape slot whose dimensions are only $0.136~lambda times 0.228~lambda$ at the lowest frequency of operation can provide more than 20% bandwidth, covering a frequency range of 410?485 MHz.

Analysis of electromagnetic scattering from an overfilled cavity in the ground plane

In this paper, we consider the scattering of the time-harmonic plane wave by a protruding cavity embedded in the PEC ground plane. An artificial boundary condition is introduced on a semicircle enclosing the cavity that couples the fields from the infinite exterior domain to those inside. Variational formulations for the TM and TE polarizations are derived and existence and uniqueness of weak solutions are established. Finite element error analysis is also performed. Numerical experiments demonstrate the efficiency and accuracy of the method.

The performance properties and limitations of antenna elements spaced closely to PEC, PMC and electromagnetic bandgap ground planes

The performance properties and limitations of antenna elements spaced closely to PEC, PMC and electromagnetic bandgap ground planes

An improved approach to predict far fields for infinite planar structure in FDTD simulations

This paper presents an improved approach to predicting the far fields for infinite planar structures using the finite-difference time-domain (FDTD) techniques. We have found that the equivalent magnetic current decays much faster than the electric current on the surface of the Huygens' box above the patch antenna due to the presence of the PEC ground plane. Hence, we suggest that the equivalent principle and image theory should be applied to calculate the far field using only the equivalent magnetic current to reduce the size of the computational domain. The example of a single patch antenna and a patch-antenna array are employed to validate the proposed approach. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 338–343, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21164

GA-based design of artificial magnetic ground planes (AMGS) utilizing frequency-selective surfaces for bandwidth enhancement of microstrip antennas

In this paper, we present a novel approach to improving the bandwidth of microstrip antennas using frequency-selective surfaces (FSSs) as an artificial magnetic ground plane (AMG). The micro-genetic algorithm (MGA) is employed to derive an optimal FSS element configuration that achieves the zero-phase condition for the reflection coefficient of an artificial surface at the desired frequency band. Two AMG configurations for single- and tri-band applications are designed by using the MGA, and their performances are compared with those of PEC ground-plane cases after integrating the AMGs with microstrip antennas. It is demonstrated that the use of such a surface, in lieu of the conventional PEC ground plane, leads to an improvement in the bandwidth of planar antennas that are placed above the surface. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 6–13, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20532

Time domain Green's functions for lossy and dispersive multilayered media

We have introduced a fast method of calculating the time domain Green's functions for multilayered media. In this paper, we demonstrate the use of this method to compute the scalar potential Green's function for a multilayer lossy dispersive medium on a PEC ground. The strength of the method lies in obtaining the Green's function for many source-to-field distances /spl rho/ and time instances t simultaneously. It only takes 6 min 28 s to compute 100/spl times/336=33 600 space time Green's function points in Matlab on a Pentium III 867 MHz processor with 1 GB of RAM for a multilayered lossy dispersive medium.

A low‐profile circularly polarized curl antenna over an electromagnetic bandgap (EBG) surface

AbstractAn electromagnetic bandgap (EBG) surface is utilized as a ground plane for a curl antenna to achieve a low‐profile design as well as a circularly polarized pattern. The antenna height is greatly reduced compared to a normal curl antenna over a PEC ground plane. The frequency bandgap and ground plane size are discussed. Experimental results demonstrate the applicability of this concept. © 2001 John Wiley &amp; Sons, Inc. Microwave Opt Technol Lett 31: 264–267, 2001.