Vicente Gonzalez-Posadas

Multifrequency and Dual-Mode Patch Antennas Partially Filled With Left-Handed Structures

Multifrequency microstrip patch antennas partially filled with left-handed (LH) structures are presented. The presence of LH structures also enables miniaturized antennas. Thus, multifrequency, dual-mode, and miniaturized antennas based on single patches partially filled with LH structures have been obtained. First, multiple operation over several band frequencies is proven from the transmission-line theory. Then, an implementation based on microstrip patches partially filled with mushroom-like structures is proposed. Two multifrequency patch antennas have been designed, built, and measured. The first one shows two dipolar (patch like) modes at 1.06 GHz and 2.16 GHz and a monopolar mode (null at broadside) at 1.45 GHz. The ratio between the resonant frequencies of both dipolar modes can be arbitrarily chosen (by means of a proper design of the patch and the LH structures) and, in this case, is 2.04. The second antenna is designed to work at closer frequencies. In this case, the frequency ratio is dramatically reduced to produce a dual dipolar antenna working at 1.81 GHz and 2.20 GHz (giving a ratio of 1.21).

Approximate analysis of short circuited ring patch antenna working at TM/sub 01/ mode

This paper presents a study of the short circuited ring patch antenna based on the cavity model. Special attention has been paid to the fundamental mode in this geometry: the TM/sub 01/ mode. Analytical expressions for resonant frequency, fields, radiation pattern and input impedance based on this model have been developed. Simulations based on this theoretical model and experimental results show good agreement. The interesting radiation characteristics and resonant frequency of this mode are presented.

Multifrequency Self-Diplexed Single Patch Antennas Loaded with Split Ring Resonators

In this paper, a novel approach to design multifrequency self-diplexed single patch antennas is proposed. This approach is based on a square microstrip patch antenna loaded with split ring resonators (SRRs). The working frequencies can be arbitrarily chosen and frequency ratios lower than 1.07 have been achieved. In addition self-diplexing characteristics are also achieved between transmitting and receiving ports by including SRRs in the feeding lines. Several prototypes have been manufactured and measured in the X-band showing good performance. Received 17 December 2010, Accepted 17 January 2011, Scheduled 26 January 2011 Corresponding author: Javier Montero-de-Paz (jmontero@tsc.uc3m.es). 48 Montero-de-Paz et al.

Dual-Frequency Printed Dipole Loaded With Split Ring Resonators

A novel approach to design dual-frequency printed dipoles is presented. This approach is based on an antipodal printed dipole loaded with split ring resonators (SRRs). This technique allows the choice of any pair of working frequencies. Two prototypes, the first one working at 1.32 and 2.83 GHz and the second one working at 1.2 and 2.05 GHz, have been manufactured and measured. The experimental results show reasonable values for the efficiency at both working frequencies. Moreover, the obtained radiation pattern is dipolar at both frequencies with low cross polarization levels.

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.

QUAD-FREQUENCY LINEARLY-POLARIZED AND DUAL- FREQUENCY CIRCULARLY-POLARIZED MICROSTRIP PATCH ANTENNAS WITH CRLH LOADING

In this paper, a novel technique to develop multifrequency microstrip patch antennas with polarization diversity or circular polarization is presented. The proposed approach consists of exciting modes with orthogonal polarizations in microstrip patches partially fllled with Composite Right/Left-Handed (CRLH) cells. Two difierent kinds of quad-frequency single-layer patch antennas are proposed. The flrst one has two orthogonal ports with high isolation between them. The second kind of quad-frequency patch antennas consists of exciting the four modes with two orthogonal polarizations through only one port. Finally, the proposed approach is used to develop dual-frequency circularly-polarized (CP) patch antennas by exciting the modes with orthogonal polarizations in quadrature phase. Prototypes of all the designs are manufactured and measured, showing good performance.

Dual-Band Recursive Active Filters With Composite Right/Left-Handed Transmission Lines

Unique properties exhibited by metamaterial transmission lines have been previously used to design a large number of dual-band microwave passive devices, but not active ones. In this paper, a novel dual-band active filter scheme based on composite right/left-handed transmission lines is proposed. The inclusion of these types of lines as feedback sections in a first-order recursive topology can be used to generate a filtering response with two arbitrary passbands. Additionally, dual-band couplers are also required. These may be implemented by means of stub-loaded branch-line structures. As an added advantage, these elements produce a strong rejection level at the central stopband that improves the overall response. Theoretical analysis and design procedures are verified by means of manufacturing and measurement of a prototype containing a distributed amplifier.

Low-Cost Approach Based on an Eigenfrequency Method to Obtain the Dispersion Diagram in CRLH Structures

A novel method to obtain the dispersion diagram of a composite right/left-handed (CRLH) unit-cell is presented. This method is based on CRLH transmission-line (TL) theory and on the structure eigenfrequencies. First, it is shown that computing the dispersion diagram of an M unit cell CRLH TL only needs three eigenfrequencies. Then, it is shown that this method drastically reduces the total computation time to obtain the CRLH unit cell dispersion diagram (from several hours to a few minutes). A four cell resonator has been designed and built to show the accuracy of the proposed method. Good agreement between the measured prototype and resonant frequencies provided by the dispersion diagram obtained with the eigenfrequency method has been achieved

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.

Broadband Active Receiving Patch With Resistive Equalization

The active integrated antenna (AIA) concept has been applied to design a broadband receiver front-end. A design procedure for active broadband patch antennas based on resistive equalization is presented. The use of the AIA has allowed the design of efficient RF front-ends by increasing its effective gain, noise figure, and merit . In addition to improving the classical parameters, the resistive equalization technique allows enlarging the bandwidths of the active antenna parameters versus the corresponding ones in passive antennas. A receiving patch antenna (with one amplifying stage) with a measured noise figure lower than 0.6 dB in a bandwidth over 38% and an effective gain improvement of 13 dB over the corresponding passive antenna has been achieved. The -parameter has also been measured for both the active and passive antenna, resulting in a relative planar of 16 dB/K, with a ripple of 0.5 dB, over a 30% bandwidth for the active antenna versus a of 22 dB/K for a typical front-end with a passive antenna over 20% bandwidth.