Application of a simplified probe feed impedance formula to the design of a dual frequency patch antenna

A simplified probe feed input impedance for a rectangular patch antenna based on the Green's function is used to design a dual frequency matched antenna. The predicted results at design frequencies of 1.9 and 2.4 GHz are in close agreement with experimental measurements

Optimum design of a probe fed dual frequency patch antenna using genetic algorithm

Abstract: Recent research has concentrated on different designs in order to increase the bandwidth of patch antennas and thus improve functionality of wireless communication systems. An alternative approach as shown in this paper is to design a matched probe fed rectangular patch antenna which can operate at both dual frequency (1.9 GHz and 2.4 GHz) and dual polarisation. In this design there are four variables, the two dimensions of the rectangular patch, ‘a ’ and ‘b ’ and position of the probe feed ‘Xp ’ and ‘YP’. As there is not a unique solution Genetic Algorithm (GA) was applied using two objective functions for the return loss at each frequency. The antenna was then modelled using AWR software and the predicted and practical results are shown to be in good agreement. Key Words: Genetic algorithm (GA), dual frequency, dual polarisation, probe fed patch antenn

Effect of losses in an active device and harmonic network on the efficiency of Class F and inverse Class F power amplifiers

High frequency class F and inverse class F power amplifiers obtain high efficiency of dc to ac power conversion, by reducing the overlap of voltage and current waveforms at the output of the active device, to ensure that the power dissipated in the resistance Ron of the active device is minimised. In this paper the active device is modelled as a switch in series with resistance Ron 0 to 5Ω. For ideal switch voltage / current waveforms and equal dc input power for both amplifiers the efficiency of power conversion is compared. To confirm the predicted results ideal lossless load harmonic networks using lumped elements were designed to meet all frequency conditions of the two amplifiers. These networks were done used in Advanced Design System (ADS) software for Ron=0, 2 and 4 Ω. The predicted efficiency for 2Ω and 4 Ω were 80% and 60% and the obtained simulation efficiency were 83.2% and 65.5% for class F amplifier. For the inverse class F amplifier the predicted efficiency was 87.3% and 74.5% and for the simulation results it was 87.26% and 74.4%. Above predicted and simulated results show that the resistance Ron has less effect on the efficiency of inverse class F than for class F amplifier. As lumped elements can not be used at high frequencies they were replaced initially with lossless transmission lines and then by microstrip lines to also investigate also how copper and dielectric losses affect the efficiency of power conversion

Moment method analysis of an aperture coupled microstrip antenna with multilayer superstrate

Microstrip patch antennas are often required to operate in non-homogeneous layered structured. The ideal feed of system for this type of antenna is an aperture coupled arrangement which required no physical contact between the antenna and feed. The microstrip feedline on the lower surface of the bottom substrate is coupled electromagnetically through a small aperture in the ground plane to the patch on the upper surface of the upper substrate. This paper presents a moment method analysis of this structure to determine the input impedance and far field radiation pattern. Results are in good agreement with measured results

To design and model a Class F amplifier and investigate the effect of losses on the efficiency of dc to ac power conversion

A detailed design of class-F power-amplifier with a load harmonic network for third harmonic peaking is presented where initially ideal lossless transmission lines and then microstrip lines with losses are used. When the load network is realized using microstrip lines the effect of discontinuities is taken into account. For a network with ideal transmission lines, a 3Ω resistor is used in series with a switch to obtain the predicted efficiency of 75%. Replacing the by microsrtrip lines and neglecting the effect of the discontinuities but with losses included the efficiency was 65.6%. When the discontinuities are included but the network not optimized the efficiency reduced to 63.5%. By tuning the network with discontinuities to obtain the required impedances at the three frequencies the efficiency increased to 67.9%. It can be concluded that the substrate losses have a major effect on the efficiency of power conversion. This shows it’s important to use low loss substrates such as Duroid with a loss tangent is 0.002 where as for PCB it is 0.019 produce higher efficiency of power conversion

En dominant design på den svenska marknaden för mobila betallösningar? En rapport om olika mobila betaltjänster och dess utmaningar.

Circular polarised antennas are used in many wireless communication systems where it is necessary to have a wide bandwidth of the return loss and the axial ratio. This paper compares the bandwidth of the above parameters for a circular polarised square patch antenna fed by a two branch coupler and a ring coupler. The design of the two couplers and the patch is initially reviewed. Based on the equivalent circuits of the two couplers and that of the patch the complete antenna is modelled using Microwave Office (AWR) software. The results obtained show that a ring coupler produces a wider bandwidth for the return loss and axial ratio than that obtained by a two branch coupler

Broadband patch antenna with ring slot coupling

A novel broadband linearly polarised patch antenna design is achieved using an H-shaped patch coupled to a microstrip feed line via a ring slot in the ground plane. The results indicate that a wide impedance bandwidth of 54% (2.3-3.845 GHz) can be achieved, together with a broadband gain of 6.6 dB and low levels of cross-polarisation