J. S. Dolado

Enhanced millimeter-wave transmission through subwavelength hole arrays

We explore, both experimentally and theoretically, the existence in the millimeter-wave range of the phenomenon of extraordinary light transmission through arrays of subwavelength holes. We have measured the transmission spectra of several samples made on aluminum wafers by use of an AB Millimetre quasi-optical vector network analyzer in the wavelength range 4.2-6.5 mm. Clear signals of the existence of resonant light transmission at wavelengths close to the period of the array appear in the spectra.

Enhanced millimeter wave transmission through quasioptical subwavelength perforated plates

In this paper, we show that the phenomenon of extraordinary transmission through arrays of subwavelength holes, present in the optical regime, is also present in the millimeter wave range. After presentation of the theoretical foundations of the enhanced transmission, measurements of the transmission response have been performed on different samples by using a millimeter wave quasioptical vector network analyzer in the range between 45 and 110 GHz. The prototypes have been fabricated in Aluminum plates with several thickness and different hole diameters drilled by using a laser machine. Good agreement between theory and experiment is obtained, with clear signals of the existence of resonant transmission at wavelengths close to the period of the array. Possible applications in frequency selective surfaces and near-field imaging are envisaged.

Very low-profile "Bull's Eye" feeder antenna

In this letter, a very low-profile planar horn antenna is proposed. It consists of a subwavelength aperture placed into a Bulls Eye concentric periodic corrugated conducting plate that produces good return losses and a narrow radiated beam. The antenna is excited by means of a waveguide whose flange has been properly mechanized in the rear part of the structure. The mechanism explaining this phenomenon is similar to the enhanced transmission observed at optical wavelengths in similar structures. In this work, the circularly corrugated structure has been scaled into the microwave frequency range and, moreover, the plane wave excitation has been replaced by a subwavelength aperture excited by a conventional closed metallic waveguide. This transforms the original focusing structure into a new concept of a very low-profile feeder with potential applications.

Dual-band low-profile corrugated feeder antenna

A dual-operating-band planar horn antenna having very low profile is presented in this paper. By opening a subwavelength aperture into a corrugated conducting plate, good return losses and a narrow radiated beam in each of the two desired operating frequency bands can be measured. This behavior is very similar to that observed in optical wavelengths where enhanced transmission was measured through apertures etched in metallic corrugated plates. Here, the double-corrugated structure has been scaled into the microwave frequency range and the excitation has been done by a conventional closed metallic waveguide placed in the rear part of the structure. In this way, a new concept of a very low profile feeder is proposed with potential wireless applications.

Very Low Profile and Dielectric Loaded Feeder Antenna

In this letter, very low profile planar horn antenna feeders are designed and measured. Using previous results of antennas consisting of a narrow slot on a metallic plane and flanked by two grooves, a further step is given here by reducing the thickness of the prototype. A key factor in the approach is the operation in the transversal slot resonance instead of the usual longitudinal slot resonance. Moreover, by inserting a dielectric material of relative permittivity epsivr > 1, the thickness can be further reduced, maintaining and even improving the radiation features of the prototype. Reducing the metallic plate thickness has important consequences in the weight and profile of the antennas, making them easy to handle and to fit into different structures. In addition, in ranges where the wavelength is of the order of centimeters, a thick metallic plate can be a serious drawback due to mechanical restrictions. In these cases the design following the rules given in this letter can alleviate this constraint.

Low-profile corrugated feeder antenna

A very low-profile planar rectangular horn antenna made of a subwavelength aperture surrounded by two grooves on the conducting plate is presented. This structure exhibits good return losses and radiated beam. Its operation is based upon enhanced transmission and beaming through apertures in metallic corrugated plates. Here, the corrugated structure is designed to operate in microwaves and, moreover, a waveguide flange, which has been properly mechanized in the rear part of the structure, is employed for excitation. A new very low-profile planar feeder with reduced size is introduced that could be properly scaled for potential wireless applications.

Enhanced microwave transmission using a subwavelength slot in corrugated plate

The new phenomenon related with enhanced microwave transmission and beaming through a subwavelength slot placed into a corrugated conducting plate has been experimentally observed, in the microwave range, compared with the case of the single isolated slot. It is very similar to that happening for optical wavelengths where the surface plasmons model is employed to describe the metal. The phenomenon is also present in the microwave range where the perfect conductor model applies. Future applications in antennas can be possible.

Transmission in cut-off hole arrays

We show that the phenomenon of extraordinary transmission though arrays of subwavelength holes is also present in the microwave range as it occurs in the optical regime. Following simulations of the influence of the number of holes, a prototype has been designed and fabricated in an aluminum plate. By using a millimeter wave quasioptical vector network analyzer in the range between 40 GHz and 110 GHz, measurements of the transmission response have been performed. A resonant total transmission at wavelengths close to the period of the array appears in the spectra opening the possibility of exciting future applications.

Comments on “A High-Gain Antenna Consisting of Two Slot Elements With a Space Larger Than a Wavelength”

This paper presents a comment on the paper titled a high gain antenna consisting of two slot elements with a space larger than a wavelength. It is observed that both slot resonances have similar current distribution and demonstrated that gain can be enhanced using any of them. Thus, implicit in this approach is that the study of the saturation of gain with the number of grooves could be applied to any of those resonances.

Subwavelength hole arrays, and split ring resonators based metasurfaces for frequency selective surfaces

This paper shows several possibilities for the design of metasurfaces based on etching holes in metallic plates, making corrugations surrounding an slit on the plate, and by introducing the concept of complementary split ring resonator. Enhanced transmission phenomena has been experimentally demonstrated in all three cases.