E. Korolkiewicz

Efficient impedance coupling formulas for rectangular segment in planar microstrip circuits

A rectangular patch is one of the most common microstrip segments for which the Greens function is known and is used in the segmentation and desegmentation analysis of complex antenna structures. The coupling impedances between ports on a microstrip segment are derived by integrating the associated Greens function to obtain a result which involves the evaluation of double infinite series. In this paper the double infinite series is replaced by a single term together with a single infinite series to produce a computationally more efficient formula for the coupling impedance. Three coupling port configurations are examined and in each case numerically efficient formulas are derived.

Investigation of the Equivalent Circuit Parameters and Design of a Dual Polarised Dual Frequency Aperture Coupled Microstrip Antenna

This communication presents a simplified approach to the design of a single feed dual polarised, dual frequency (1.9 and 2.4 GHz) aperture coupled microstrip antenna. Using simulation and practical investigation, the coupling between the microstrip feed line and aperture, along with the coupling between the aperture and patch, is investigated and modelled using equivalent transformers. The results obtained are used to reduce the number of interdependent design parameters, thereby allowing initial approximate values to be determined more directly with only fine tuning subsequently required to obtain good matching at both frequencies. Excellent agreement is obtained for the simulation and practical results of the return loss and the gain of the antenna.

Improved design technique of a broadband class-E power amplifier at 2GHz

Using a new design a high efficiency power amplifier, to improve the bandwidth, is presented. Previous analytical efforts have focused on designing the class-E output network at a single frequency, which results in a narrow frequency bandwidth. In this paper, we present a method for calculating the optimum circuit parameters to maximize the power-added efficiency (PAE) over a wider bandwidth. Simulation and practical results confirm the validity of the approach. A circuit in PCB technology using a medium-power packaged transistor was fabricated, yielding a peak PAE of 82.1% at 1.99GHz with 22.8dBm output power. A PAE greater than 60% from 1.87GHz to 2.11GHz was achieved.

Design of a three port feed matching network for a dual-band and dual-polarized rectangular patch antenna

This paper presents practical design of a three port feed network for a dual-band and dual-polarized patch antenna operating at 1.9 GHZ and 2.4 GHz. Initially, design graphs are used to determine the dimensions of the patch for dual band application and the component values of the two equivalent parallel tuned circuits of the antenna at each frequency. Finally the predicted and practical results are compared.

Removal of surface-wave induced radiation nulls for patch antennas integrated with vehicle windscreens

A solution to the problem of radiation nulls for patch antennas integrated with vehicle windscreens is presented. The nulls, attributable to surface waves within the windscreen superstrate, are removed by the addition of a thin resistive film to the windscreen surface. Analysis of the surface-wave modes at 5.8 GHz within two typical laminated windscreen structures coated with a resistive film shows a sheet resistance value of 50 /spl Omega//sq to be appropriate. Polar-pattern results demonstrate the effectiveness of the technique in removing the radiation nulls without significantly reducing the forward gain.

Efficient Coupling Impedance Formulas for the Right-angled Isosceles Triangular Patch for Use in Segmentation Analysis

An explicit and computationally efficient coupling impedance formula for the coupling between two perimeter ports on a perpendicular side of a right-angled isosceles triangular patch microstrip segment is derived. Based on coplanar circuit analysis an initial impedance formula is obtained in terms of a single and a double infinite series expression. Application of closed forms for the series reduces the single series to a closed form, and, the double series reduces to a single series. The new computationally efficient coupling formula is verified by comparison with simulation based on full wave analysis, and, practical measurement

Design of a circular polarized nearly square microstrip patch antenna with offset feed

This paper presents the design of a circular polarized nearly square patch antenna using an offset microstrip feed. By using an offset feed instead of the normal corner feed, it is shown that the area of the perturbation segment must increase in order to maintain circular polarization. Consequently, the effect of manufacturing errors on the axial ratio is reduced. Using a fixed offset feed position, the dimensions of the antenna are uniquely obtained. The antenna is matched using a simple matching network consisting of a short length of microstrip line. A matched antenna was designed to operate at 2.45 GHz, and an axial ratio of <0.5 dB with a return loss of >20 dB was obtained experimentally. The predicted, simulated and practical results are shown to be in good agreement.