Jose Luis Jimenez-Martin

Dual Band High Efficiency Class Ce Power Amplifier Based on CRLH Diplexer

In this paper, the most adequate architecture to implement dual frequency ampliflers is shown. Composite Right/Left Hand (CRLH) and Extended Composite Right/Left Hand (ECRLH) transmission lines are studied and evaluated to flnd the most suitable structure for dual band power ampliflers. As an example, the performance of a class CE amplifler, working in TETRA and GSM frequency bands, is compared with simulations and measurement, showing good agreement.

Oscillator Accurate Linear Analysis and Design. Classic Linear Methods Review and Comments

This paper is a deep analysis of oscillator plane reference design methods. It deflnes applicable conditions and the expected accuracy that can be archived with these methods. Some examples will be shown to illustrate wrong solutions that the use of linear reference plane methods can produce. The wrong solutions will be justifled by necessary conditions for proper use of these methods. The strengths and weaknesses of the, widely used, plane reference methods are described in this paper. Several classic topologies of microwave oscillators, as Grounded Collector Tuned Bases(GCTB) and Grounded Bases Tuned Oscillator (GBTO), are used to illustrate these results and the additional required conditions.

Lumped-Element Balun for UHF UWB Printed Balanced Antennas

A semi-lumped balun transformer for UHF and ultrawideband (UWB) dipole antennas is presented in this paper. The proposed structure is based on two asymmetric filters that also transform the variable antenna impedance into the desired source impedance. These asymmetric filters make use of a binomial impedance transformer in each filter section. The asymmetric filters (one low pass filter, LPF, and other high pass filter, HPF) allow the balun bandwidth to be increased while the binomial transformer matches the variable balanced dipole impedance. In this way the ripple in the balun response due to the variation of the UWB dipole impedance is reduced. A balun for a UHF and UWB dipole antenna working from 220 to 820 MHz (bandwidth of 4:1) has been achieved with losses lower than 1 dB. These types of baluns are particularly useful in the low microwave frequency band.

Transpose Return Relation Method for Designing Low Noise Oscillators

In this paper, a new linear method for optimizing compact low noise oscillators for RF/MW applications will be presented. The flrst part of this paper makes an overview of Leesons model. It is pointed out, and it is demonstrates that the phase noise is always the same inside the oscillator loop. It is presented a general phase noise optimization method for reference plane oscillators. The new method uses Transpose Return Relations (RRT) as true loop gain functions for obtaining the optimum values of the elements of the oscillator, whatever scheme it has. With this method, oscillator topologies that have been designed and optimized using negative resistance, negative conductance or re∞ection coe-cient methods, until now, can be studied like a loop gain method. Subsequently, the main disadvantage of Leesons model is overcome, and now it is not only valid for loop gain methods, but it is valid for any oscillator topology. The last section of this paper lists the steps to be performed to use this method for proper noise optimization during the linear design process and before the flnal non-linear optimization. The power of the proposed RRT method is shown with its use for optimizing a common oscillator, which is later simulated using Harmonic Balance (HB) and manufactured. Then, the comparison of the linear, HB and measurements of the phase noise are compared.

Non-Foster matching of Electrically Small Antennas. Stability considerations

Stability is the biggest problem in the matching of Electrically Small Antennas (ESAs) using non-Foster reactances realized by Negative Impedance Converters (NICs). However, it is not usually studied properly. In this paper we propose the Normalized Determinant Function (NDF) as a powerful method to test the stability of the systems formed by the NIC and the ESA, and we will show how conventional design can lead us to unstable solutions.

Novel Diplexer made with Dual-Composite Right/Left-Handed Lines (D-CRLH)

In this paper the use of dual-composite right/left hand (D-CRLH) transmission lines is proposed for the design of diplexers. The D-CRLH diplexers present advantages over conventional diplexers such as smaller size. The design procedure and the design equations are presented in this paper. The non-linear phase response of a D- CRLH transmission line has been used to design arbitrary diplexers. An example illustrating the synthesis procedure is presented. Finally, the simulation results are compared with the measurement showing good agreement. These results confirm the excellent performance of the proposed circuit. These types of diplexers are particularly useful at the low microwave and UHF bands.

Advantages of NDF as oscillator linear design tool: design of a NIC active patch antenna

This paper shows one active patch antenna with a Negative Impedance Converters (NIC) and other one without it. The NIC works as negative admittance to increase the Q of the antenna. These circuits can be analysed using classic methods, but classic methods require the verification of the appropriated provisos. The chosen classic method depends on the oscillator topology, while the Normalized Determinant Function (NDF) is independent of topologies and it does not require any provisos. The NDF is suitable for Q estimation and noise optimization during linear analysis of any topology. The oscillators are designed using the NDF and the Admittance; then the phase noise is evaluated using the NDF. The Harmonic Balance (HB) analysis and the measurements of the prototypes confirm, in favour of NDF, the stability discrepancies between classic methods and NDF. The linear approximation of the improvements introduced by a NIC is questioned by the risk of instabilities and the introduction of new noise sources.

Low-Cost Measurement for a Secondary Mode S Radar Transmitter

A low-cost, multiple-purpose, and high-precision timing test setup for the measurements of secondary Mode S radar transmission signal was proposed. The goal was to fully guarantee compliance of the proposed transmitter under test with the really hard International Civil Aircraft Organization requirements using traditional measurement equipment, which was difficult or even impossible to ensure up to now. The low-cost structure proposed in this paper allows the user to perform measurements independently of the measurements performed by the pieces of test equipment shelled by the manufacturer of radar, which is a very important aspect since the independence of the verifications is a mandatory requirement established by the safety standards of civil aviation. The proposed setup has been used to verify several transmitters with some defects that are not detected by monopulse secondary surveillance radar specific pieces of test equipment that are focused on more high-level functionalities. It also is valid and it has been used, as a general-purpose setup, for testing other radio navigation aids.

Lumped high-low pass balun for ultra wide band printed balanced antennas

A semi-lumped balun transformer for UHF dipoles is reported in this paper. The proposed structure utilizes two filters plus one small transmission line. This circuit does not require any multilayer either suspended substrates techniques. Its broadband behaviour is due to the use of lumped elements; this is particularly useful for low microwave band. The key idea is to use a geometrical progression for the characteristic line impedance and extract the values of the lumped elements from those values. Several baluns have been built to demonstrate the electrical feasibility in wideband UHF dipoles. Finally, a broadband monopole is attached to the balun to show its performance.

Dual band and dual polarization short-circuited ring patch antenna

This paper presents a modification of the short-circuited ring patch antenna that operates in two bands: the lower band with linear polarization and the upper band with circular polarization. The new single-feed antenna has been manufactured and a comparison between measurements and numerical simulations is shown. Different characteristics such as radiation patterns, gain, and resonant frequencies have been analyzed. Moreover, a parametric study has been performed in both bands.