Iulia Andreea Mocanu

Electromagnetic study of strong coupled CRLH transmission lines for use in antenna construction

In this paper there are studied the electromagnetical phenomena which appear when coupling two Composite Right-Left Handed (CRLH) artificial transmission lines with different cells dimensions, one of them being two times smaller. There are analyzed the frequency ranges where the strong coupling appears and also, the differences between the simulated results and the measured ones are compared.

Backward couplers using coupled composite right/left-handed transmission lines

A new asymmetric backward coupler is obtained by edge-coupling two types of composite right/left handed (CRLH) lines. This novel coupler is analyzed in a microwave range (1–10 GHz) and the magnitude of the scattering parameters reveals tight coupling effects (even 0 dB) in a dual frequency band and also very good directivity in the working band.

The study of different types of D-CRLH transmission lines for microwave diplexer

The Dual Composite Right Left Handed (D-CRLH) transmission lines are a newly introduced type of artificial transmission lines with various microwave applications [1]. This study investigates different types of implementation of these transmission lines and the influence over the performances. The study is carried using both lumped elements and microstrip implementation of the unit cells. The relations of calculus for the lumped elements are validated using simulation. The number of cells, as well as the type of symmetry used in implementing such lines is an important aspect to be considered when creating microwave devices, so it was also investigated.

38 GHz metamaterial antenna on silicon substrate

This paper present the results in designing, processing and measurements of a zeroth-order resonance (ZOR) antenna in the mm-wave frequency domain using Composite Right/Left-Handed (CRLH) structures. Antenna was fabricated on high resistivity silicon substrate seeking for a subsequent integration in a more complex mm-wave circuit. Experimental results show S11 <; -45 dB at 38.47 GHz, -3 dB beamwidth of the transversal radiation lobe approx. 17° and the gain Gi= 1.67 dBi at 38.5 GHz.

Novel directive coupler with dual band behavior for GSM applications

A miniaturized directive coupler with dual band behavior is presented in this paper. It is suitable for GSM applications and demonstrates good performances in both imposed bandwidths. The physical implementation is done using lumped elements with high quality factor and micro-strip technology with low losses. This ensures good performances while maintaining the dimensions of the device as small as possible. A directivity of around 30dB is achieved for both frequencies; meanwhile the phase imbalance is smaller than one degree at the two imposed frequencies.

Steering capability of a mm-wave left-handed transmission line antenna

The paper presents the results concerning the radiation characteristic scanning of a ferrite supported mm-wave (30 GHz) Zeroth-Order Resonating (ZOR) CoPlanar Waveguide (CPW) antenna based on Composite Right/Left-Handed (CRLH) transmission lines. The scanning effect is obtained by magnetically polarizing the ferrite substrate. The measurements demonstrate steering of the radiation characteristic between approx. -15° to +14° depending on the strength of biasing magnetic field between 0 T and 0.265 T. Concerning the gain, in the unbiased state the antenna gain is 4.16 dBi and increases slightly to 4.22 dBi due to small field loss reduction followed by the application of the biasing magnetic field. Also, the return loss is reduced as a result of eliminating ferrites low field loss.

MM-Wave Metamaterial Adjustable Antenna on Magnetically Biased Ferritic Substrate

The paper presents a mm-wave metamaterial coplanar waveguide (CPW) zeroth-order resonating (ZOR) antenna on magnetically biased ferrite substrate. The measurements demonstrate tuning of the resonant frequency and steering of the radiation characteristic depending on the strength of biasing magnetic field. The resonant frequency shifts about 1.1 GHz for magnetic biasing field strength variation between 0 T and 0.265 T. The return loss is reduced as result of elimination of ferrite low field loss. The radiation characteristic in transversal plane steers between approximately −15° and

Method of CRLH Antenna Impedance Measurement by Means of On-Wafer Characterization Equipment

The paper deals with a measurement method of the input impedance in the radiating section of a coplanar waveguide (CPW) Composite Right / Left-Handed (CRLH) antenna. In this respect were used the technical facilities offered by an on-wafer measurement equipment contacting the antenna feeding line. With appropriate formulas derived from the theory of the transmission lines, the resistive Rs and the reactive Xs parts of the CRLH radiating structure impedance Zs = Rs + jXs were found. The results for three antenna samples were: Zs1 (Ω) = 48.5326 - j×16.9639, Zs2 (Ω) = 48.6053 - j×16.8143 and Zs3 (Ω) = 48.1786 - j×16.3707. As it is normal, the reactive parts of the measured impedances are negative due to the CRLH line construction with series interdigital capacitors inducing left hand behavior.

Microstrip structures with behavior of left-handed materials

New multilayer microstrip structures are investigated in microwave range. Due to the use of stepped impedance resonators (SIR), the multilayer microstrip left-handed transmission lines are more compact than the structures with conventional split ring resonators. The amplitude and phase responses are analyzed for different geometrical parameters, number of cells and dielectric constants of the substrates. It is shown that the investigated structures exhibit left-handed properties in a frequency range near the SIR resonance.