Mariano Baquero-Escudero

A novel band-pass filter topology for millimeter-wave applications based on the groove gap waveguide

In this paper a new type of band-pass filters for high frequency applications (40 GHz and beyond), with very good electrical performance and enhanced manufacturing flexibility, is demonstrated. These filter structures are based on the recently proposed groove gap waveguide, which is just made of two simple metal blocks separated by an air gap. This means that electrical contact between the two metal blocks is not needed, thus involving several advantages when compared to standard rectangular waveguide filters operating at millimeter-waves. A 4th order band-pass filter with a response centered at 40 GHz and a 2.5% fractional bandwidth has been designed, manufactured and verified with experimental results.

Compact Wideband Vivaldi Monopole for LTE Mobile Communications

A novel compact broadband monopole antenna inspired by a Vivaldi antenna is presented. In order to get a compact solution, the profile of a slot Vivaldi antenna has been modified and a wideband antenna covering LTE700, GSM850, GSM900, DCS1800, PCS1900, WCDMA2100, Bluetooth, WiMAX2350, WLAN2400, and LTE2600 standards has been obtained, with a size reduction length of 30% over conventional λ/4 monopole antennas. In contrast to traditional designs using Vivaldi antennas, a compact design with omnidirectional radiation pattern is proposed. Simulated and measured results are provided, which verify the broadband behavior of the antenna. In addition, the proposed design is perpendicularly mounted to a ground plane, being then suitable for mobile communications in vehicular applications.

Propagation Characteristics of Groove Gap Waveguide Below and Above Cutoff

Recently, gap waveguides have been shown as a potential alternative to convenational waveguides in the millimeter-wave band. Until now, groove gap waveguide (GGW) has been studied through direct correspondence with rectangular waveguide with the same physical dimensions. However, there have been observed differences in the above cutoff propagation characteristics between these two waveguide types. Furthermore, the behavior of GGW below cutoff remains unknown. This work presents a discussion of both below and above cutoff propagation characteristics of GGW, and introduces a simple model that explains the observed GGW behavior and establishes well its propagation characteristics. Two thru-reflect-line calibration kits have been manufactured, and the measurements have good agreement with the proposed analysis model results.

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This paper describes the design and realization of a transition from a microstrip line to a ridge gap waveguide operating between 95 and 115 GHz. The study includes simulations, measurements, and a Monte Carlo analysis of the assembly tolerances. The purpose of this tolerance study is to identify the most critical misalignments that affect the circuit performance and to provide guidelines about the assembly tolerance requirements for the proposed transition design.

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Cylindrical near-field measurement systems are being widely demanded, especially for imaging applications at millimeter-wave frequencies. One of their most important drawbacks is the long time required to perform a full measurement of an antenna. To avoid multiple receivers, the probe is mechanically moved to the points where the field must be measured. The mechanical movement increases the time required to take a full measurement. The process may be sped up in several ways. This letter proposes the use of a pattern reconfigurable slot-array antenna as a probe. The switching among the different patterns is carried out electronically by RF-MEMS, which are placed over the different slots. Simulations and measurements of a model in the X-band are shown in this letter.

-Band Transition From Microstrip to Ridge Gap Waveguide Including Monte Carlo Assembly Tolerance Analysis

A rectangular waveguide for low-loss transmission at THz frequencies is proposed. The waveguide is based on the reflection of the fundamental mode on the side walls. By adding a stratified medium, a low impedance condition is obtained in the inner wall. Attenuation in side walls is eliminated.

Reconfigurable Slot-Array Antenna With RF-MEMS

Gap-waveguide technology is based on the guidance of a quasi-TEM mode between two PEC plates. The confinement is possible due to a PEC/PMC condition on laterals, which prohibits the propagation of waves on those directions. PMC condition is commonly created by means of a metallic bed of nails. This letter examines the possibility of using a dielectric bed of nails to impose the PMC condition. The use of such kind of nails may facilitate the insertion of active components. Measurements for a straight transmission line and a power divider are included to verify the correct behavior of the dielectric bed of nails.

Rectangular waveguide with low metallic losses on side walls at THz

Antennas designed in the THz band using conventional metallic waveguides have a poor performance due to the high losses of non-ideal conductors at THz frequencies. To avoid this problem, low-loss waveguides at high frequencies, e.g. ribbon waveguides or metallic wires, might be used. This paper presents the design of antennas in the THz band by means of a new rectangular waveguide. This waveguide is formed by a 1D-EBG structure on side walls, and a 3D-EBG structure, known as woodpile, on upper and lower walls. The resulting waveguide has a low attenuation in the THz band and allows the easy formation and fabrication of devices and horn antennas.

Dielectric Bed of Nails in Gap-Waveguide Technology at Millimeter-Wave Frequencies

Cylindrical measurement systems require two sweeps around the antenna under test (AUT). One sweep is a translation movement (vertical) and the other one a rotation movement (roll). Whereas the rotation movement is normally done by the AUT, the translation movement is commonly carried out by the probe [1]. This translation can be avoided by using a probe with a reconfigurable pattern. Thus, instead of moving the probe physically, the probe pattern is electronically swept from one side to the other side of the probe [2]. By doing so the vertical scanning is performed faster.

EBG structures for antenna design at THz frequencies

The knowledge of the equivalent currents of an antenna could become one of the most important aspects during its design process. This information can be obtained by knowing the currents obtained from the radiated field of the antenna. As this is usually measured in the near field region, is necessary to obtain a relationship between near field and equivalent currents. Basically, the process described in a previous paper obtains the far field from the near field measurements and with this far field calculates the plane wave spectrum. If this process is followed the maximum resolution achievable is 1 lambda. The reason for such a poor resolution is the use of only the visible spectrum. However, we need this non-visible spectrum to achieve a better resolution. For this reason we propose in this paper the combination of two techniques to obtain the non-visible spectrum. These techniques are the fft iterative method and the second technique is using the lattice of the spectrum to improve results. The use of both increases considerably the resolution of the reconstruction