Lens_antenna_based_on_fresnel_zone_lens.pptx

Lens_antenna_based_on_fresnel_zone_lens

1. 09-09-2013 ICEAA 2013 1 LENS ANTENNA Based on Fresnel Zone Lens of Flat Dielectric Rings Conformal to Conical Surface ------------------------------------------------------------ H. D. Hristov 1 , J. M. Rodriguez 1* , J. R. Urumov 2 , and L. P. Kamburov 2 1 Departamento de Electrónica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso, Chile, e-mail: [email protected] 2 Department of Communication Technique and Technologies, Technical University of Varna, Varna, 9010, Bulgaria, e-mail: [email protected]

2. 09-09-2013 ICEAA 2013 2 I. Introduction Dielectric lenses/lens antennas are key devices in many millimeter and terahertz systems Under some size limitations, like the constant aperture size , achieving superior antenna parameters is a very important and challenging task. The lens antenna with diffraction curvilinear (3D) Fresnel zone (FZ) lens (like the recently proposed cone-shape flat-ring FZ lens , marked as CFZf. α . ν ), can be much lighter, and cost-effective antenna compared to the same aperture-size antenna with an ordinary refraction lens or 2D FZP lens. Low-THz CFZ flat-ring lens antenna with a 229-GHz CFZf.6.75 lens is studied here by use of CST computer-simulation

3. 09-09-2013 ICEAA 2013 3 II. Cone Fresnel Zone Lens Focusing II.1 Flat-ring lens design Lens consists of half -wave ( phase-reversal ) flat dielectric rings conformal to a conical surface . A plane wave is illuminating normally the rings .

4. 09-09-2013 ICEAA 2013 4 II.2 Difractive cone -ring & flat-ring FZ lenses ( a) (b) (c) (d) In lens CFZc.3.45 (a), the conical rings and conical surface have the same semi-opening angle α =45deg. In all other lenses (cases (b)-(d)) the flat-ring lenses are illuminated normally , while the surface opening semi-angle α varies : for lens CFZf.3.45 α = 45deg (b), for lens CFZf.5.30 α = 30deg (c), and for lens FZP α = 90deg (d).

5. II.3 Constructional note For a constant aperture size the main CFZ lens drawback is its increased axial length . But as it is seen from the volume contrast below between the FZP (a) and CFZ (b) lens antennas, the lens configuration does not affect the lens antenna encased volume , which also includes the antenna feed. 09-09-2013 ICEAA 2013 5 (a) (b)

6. 09-09-2013 ICEAA 2013 6 In this work 3 antenna lens configurations with F/D=0.7 are designed for: frequency f =229 GHz (wavelength λ =1.31mm ) focal length F =30 mm lens diameter D =42.6 mm . The dielectric used for each lens is polyethylene with a relative permittivity eps =2.25 and loss tangent= 0.0004 . The lenses are illuminated by an open waveguide (OWG) feed , which radiation pattern is shown in some of the slides below. The same OWG feed, has been in used for illumination of each of the three studied lenses: cone flat-ring FZ lens, plane FZP lens and ordinary plane-hyperbolic lens. II.3 Lens/ a ntenna design data

7. II.4 Lens focusing: numerical results 09-09-2013 ICEAA 2013 7 CFZf.6.75 PH PH Axial lens field distribution for: CFZf.6.75 lens (left) and PH lens (right). Observation: CFZf.6.75 lens has notoriously better axial resolution, which is due to the specific conical disposition of the phase-shifting rings leading to a reduced axial spherical lens aberration , compared to PH lens.

8. 09-09-2013 ICEAA 2013 8 CFZf.6.75 PH Focusing field distribution in the transverse focal plane of CFZf.6.75 and PH lenses illuminated by plane wave Lenses G F (dB) ΔX/ λ ΔY/ λ ΔZ/ λ FZP lens 25.4 0.85 0.89 4.31 CFZ.6.75 lens 26.7 0.74 0.79 3.14 PH lens 27.3 1.03 1.03 6.18 Table I Lens focusing gain G F (dB), transverse (ΔX/ λ & ΔY/ λ ), and axial ΔZ/ λ resolutions (in wavelengths ) ( dB)

9. 09-09-2013 ICEAA 2013 9 III. Lens Antenna with Cone Fresnel Zone Lens III.1 Antenna consisting of CFZf.6.75 lens and OWG feed Lens antenna configuration (left), OWG feed radiation patterns: E- , H- , and 45-deg plane co-polar patterns, and 45-deg cross-polar pattern (middle), and near-field distribution of the lens antenna (right);

10. 09-09-2013 ICEAA 2013 10 III.1 CFZf.6.75-lens antenna radiations patterns (left) Radiation patterns of CFZf.6.75-lens antenna (right) Radiation patterns of PH-lens antenna E - and H -plane co-polar patterns, and 45-deg cross-polar pattern

11. Table II Radiation parameters of lens antennas 09-09-2013 ICEAA 2013 11 Observations: CFZ.f.6.75- and PH- lens antennas feature c comparable gains and beamwidths ; CFZ.f.6.75-lens antenna is superior by about 3dB in maximum cross-polar level but inferior by 1.8dB in maximum sidelobe level compared to PH-lens antenna Lens antennas G A (dB) HPBW ( deg ) SL (dB) XP (dB ) FZP 30.7 1.85 -20.5 -37.0 CFZf.6.75 32.0 1.85 -19.8 -33.1   PH 32.6 1.95 -22.6 -30.3

12. CFZ.6.75-lens antenna has a -3 dB bandwidth of 35 GHz, or about 15% relative to the design frequency. In contrast, the PH-lens antenna bandwidth is much less-around 80% ; The focal spot location of the FZ lenses is highly frequency dependent, and the corresponding lens antennas are narrowband. 09-09-2013 ICEAA 2013 12 PH CFZ.6.75 FZP III.2 Frequency bandwidth of lens antennas

13. Conclusion 09-09-2013 ICEAA 2013 13 Near to design frequency of 229GHz , the novel mm-wave lens antenna based on the cone-shape lens CFZ.6.75 is similar in gain and radiation pattern in a much narrower frequency band compared to the PH lens antenna of same aperture diameter and focal length. On the other hand, the flat-ring dielectric CFZ lens/antenna construction is much lighter and has significant structural and technological advantages , especially at the microwave frequencies. The CFZ-type lens can be easily fabricated from microwave to THz and optical frequency bands as a multilayer package of flat dielectric or metal rings embedded in a low-permittivity solid, fluid or air space .

14. Remark : Current Experimental Work at UTFSM 09-09-2013 ICEAA 2013 14 We just started experimental work on a lens focusing in the low THz band (220-320 GHz). The initial results show a good match between the theoretical and numerical focusing data. Experimental setup CFZ.3.45 Lens (Radiometer-Physics + Thorlabs ) Prototype

15. THANKS FOR YOUR ATTENTION! 09-09-2013 ICEAA 2013 15