Effect Of Finite Ground Plane Research Articles

Wideband Millimeter-Wave Endfire Antenna Based on Symmetrical Spoof Surface Plasmon Polaritons

A wideband and high-gain planar endfire antenna based on spoof surface plasmon polaritons (SSPPs) at millimeter-wave (MMW) band is presented. First, a unilaterally corrugated surface antenna is demonstrated to radiate endfire beam tilted up from the flat plane of the corrugated metal teeth due to the effect of finite ground plane. Then, a SSPPs endfire antenna is designed with two symmetrically corrugated surfaces on the double sides of a metal strip. To excite the desired beam, the feeding network is comprised of a power divider and two L-shaped slots, so as to simultaneously produce oppositely tangential electric fields and identically normal electric fields. Moreover, the two equivalent identically tangential magnetic current sources above the corrugated surfaces are excited by flared feeding slot transitions. As a result, a synthetic endfire beam with zero-tilted angle is achieved. In final, such an antenna, operating in a range from 30 to 50 GHz with 50% fractional bandwidth, is designed with maximum gain of 16 dBi, as well confirmed in the experiment. The proposed SSPPs endfire antenna holds a very low profile and it is promising for application in MMW communication systems.

Mushroom‐shaped dielectric resonator antenna for WiMAX applications

AbstractA compact mushroom‐shaped dielectric resonator antenna (MSDRA) excited by microstrip line feeding, with partial ground plane has been designed and studied theoretically as well as experimentally. The proposed antenna has been developed for world‐wide interoperability for Microwave Access (WiMAX) applications centered at about 3.5 GHz. The total size of the antenna is 62 mm × 50 mm. The gain for the antenna is found to vary from 3 to 3.6 dBi. Parametric studies are performed to investigate the performance of the antenna. The effects of finite ground plane and radius size of mushroom (half cylindrical)‐shaped dielectric resonator on the antenna performance has been evaluated. The investigations on the S‐parameter, gain, directivity, and radiation characteristics show a fairly good agreement which justifies that the MSDRA can be well suited for Wireless communication systems. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1360–1365, 2013; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.27590

UWB Antennas Analysis Using FDTD-Based Discrete Green's Function Approach

Discrete Green's function (DGF) approach for analysis of transient response of the ultrawideband (UWB) monopole antenna has been proposed. The marching-on-in-time solution of DGF method is based on finite-difference time-domain (FDTD) equations that offer more straightforward formulation than that of time-domain integral equations (TDIEs). In addition, unlike FDTD method, calculations are performed only on the surfaces of conductors but not throughout the entire volume. The finite ground plane effect on the UWB monopole antenna performance and transient response between two antennas in face-to-face and side-by-side scenarios have been investigated using this procedure with improving the computational speed.

Circular polarisation from dual-layer square-ring microstrip antennas

Stacked microstrip square-ring antennas are investigated for circular polarisation (CP). Enhancement of axial ratio bandwidth is obtained using stacked square rings and applying corner perturbations to both parasitic and driven rings. Both negative and positive corner perturbations are used and wide axial ratio bandwidths are demonstrated. A novel approach is presented, where a combination of positive and negative perturbations is adopted in the driven and parasitic rings, respectively, which resembles a sequential rotation and offers broad axial ratio bandwidth, along with a wide axial ratio beamwidth. The effects of finite ground plane on the CP performance of this antenna are studied, and methods are presented to overcome the problems associated with the degradation of the CP performance because of the finite ground plane. The effect of positioning the antenna asymmetrically on the ground plane is also studied, which shows that the ground plane symmetry is important for the CP antenna. The measured 3 dB axial ratio bandwidth of approximately 5.15% is achieved for dual-layer square-ring antennas. The measured right-hand CP (RHCP) gain is in excess of 7 dBic for a wide frequency range. The simulation results are in good agreement with the measured data.

Pattern Studies of Two Parallel Dipoles Above Ground Plane in Eleven Configuration as Feed for Reflector Antenna

The patterns of dual dipoles above a ground plane in the so-called "Eleven" configuration are presented. It is shown that these patterns can be shaped to get different beamwidths to better fit reflectors with different F/D ratios while maintaining beam symmetry. Linear as well as curved dipoles are considered. The effect of finite ground plane is also discussed.

Antenna and receiver system with digital beamforming for satellite navigation and communications

To demonstrate and investigate the possibilities of active antennas with digital beamforming, a compact breadboard model operating in C-band with planar patches as radiators is fabricated and measured. It was originally designed as a technology demonstrator for navigation purposes, but will be extended for future use in combined navigation and communication systems. Several parameters for beam position, sidelobe reduction, and nulling are set and controlled by a suitable user interface. A special calibration and error-correction procedure is developed to compensate for drift of active elements, mutual coupling of the patches, and finite-ground plane effects. The excellent results demonstrate the versatile features of digital beamforming for satellite navigation and communication systems.

Finite ground plane effects on broad-band dual polarized patch antenna properties

Effects of finite ground plane on the isolation and radiation properties of a broad-band dual-polarized aperture-coupled patch antenna are experimentally investigated. The dual-polarized patch antenna has a thick air substrate for broad-band operation (>16% for both polarizations) and is excited by microstrip lines through two H-shaped coupling slots. Results show that by selecting suitable ground-plane dimensions, isolation between the two feeding ports can be greatly enhanced by about 10 dB, and the cross-polarization level in the E and H planes can also be improved by about 10 and 5 dB, respectively. Also, the impedance bandwidth increases with decreasing ground-plane dimensions.

Finite ground plane effect of a microstrip patch antenna: a CAD formula of impedance perturbation by synthetic asymptote and GTD

The computing time for a patch antenna with infinite ground plane using image theory is much shorter than that for a finite ground plane. As the latter is the actual practical structure, it would be of advantage to find a CAD formula to account for the impedance perturbation from an infinite ground plane to a small finite ground plane. This paper synthesises such a formula from the ground plane asymptotes aided by the GTD (geometrical theory of diffraction). The GTD has been used to study antenna patterns and backlobes. The paper completes the picture by considering radiation impedance.

Antenna size reduction using non-planar rings

There is a constant need to reduce the size of antennas without affecting their performance. The method of shorting patches to reduce the physical size of antennas is a common practice. The use of finite ground planes with these types of antennas can have a negative effect on their performance. Here, the introduction of non-planar rings in conjunction with a shorted patch to minimise the negative effects of the finite ground plane resulting in an overall antenna size reduction and an improvement in antenna performance is proposed.

Finite ground plane effects on the radiation pattern of small microstrip arrays

The radiation characteristics of microstrip antennas consisting of two patch elements on small size substrates are studied by means of an approximate solution technique. Special attention is paid to the shielding effect due to finite ground plane diffraction. Experimental and theoretical results show that the back radiation is influenced by the sidelobe level and can further be reduced when the antenna is boxed. For a correct radiation pattern computation these diffraction effects need to be included in the design of small array as well as in that of single element antennas.

Radiated emissions and immunity of microstrip transmission lines: theory and reverberation chamber measurements

The increasing complexity of electronic systems has introduced an increased potential for electromagnetic interference (EMI) between electronic systems. We analyze the radiation from a microstrip transmission line and calculate the total radiated power by numerical integration. Reverberation chamber methods for measuring radiated emissions and immunity are reviewed and applied to three microstrip configurations. Measurements from 200 to 2000 MHz are compared with theory, and excellent agreement is obtained for two configurations that minimize feed cable and finite ground plane effects. Emissions measurements are found to be more accurate than immunity measurements because the impedance mismatch of the receiving antenna cancels when the ratio of the microstrip and reference radiated power measurements is taken. The use of two different receiving antenna locations for emissions measurements illustrates good field uniformity within the chamber.

Effects of finite ground plane on the radiation characteristics of a circular patch antenna

An analytical technique to determine the effects of finite ground plane on the radiation characteristics of a microstrip antenna is presented. The induced currents on the ground plane and on the upper surface of the patch are determined from the discontinuity of the near field produced by the equivalent magnetic current source on the physical aperture of the patch. The radiated fields contributed by the induced current on the ground plane and the equivalent sources on the physical aperture yield the radiation pattern of the antenna. Radiation patterns of the circular patch with finite ground plane size are computed and compared with the experimental data, and the agreement is found to be good. The radiation pattern, directive gain and input impedance are found to vary widely with the ground plane size. >

The finite ground plane effect on the microstrip antenna radiation patterns

The uniform geometrical theory of diffraction (GTD) is employed for calculating the edge diffracted fields from the finite ground plane of a microstrip antenna. The source field from the radiating patch is calculated by two different methods: the slot theory and the modal expansion theory. Many numerical and measured results are presented to demonstrate the accuracy of the calculations and the finite ground plane edge effect.

Acoustic Modeling of Finite Ground Plane Effect on Radiation Patterns of Electromagnetic Sources

A unique approach to laboratory modeling of electromagnetic sources by employing acoustic radiation elements and wavelength scaled models of special streamlined ground plane airframes is discussed with some practical results. This technique is based on the analogy between the longitudinal acoustic and the vertically polarized electromagnetic waves, and the identical propagation and scattering characteristics of uniform plane or spherical waves in both cases assuming the medium is lossless and uniform by layers at least. The case of a linear lossy medium may also be successfully treated by normalizing it and appropriately reducing the available transmitted power for an equivalent lossless case. Another unique contribution of this work is in modeling the radiation elements of the electromagnetic type by acoustic antennas and slots, and vice versa. For instance, a special case of a monopole and a slot in electromagnetic case is shown to be equivalent to the spherical radiator in the acoustic case. Furthermore, this theoretical work is supported by laboratory data.