This is an electronic reprint of the original article.This reprint may differ from the original in pagination and typographic detail.

Powered by TCPDF (www.tcpdf.org)

This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user.

Mollaei, M. S.M.; Heydarian, R.; Zanganeh, E.; Sedighy, S. H.Triple-Bands Ka-Band Frequency Selective Surface Filter with Different PolarizedTransmitting Performance in Each Band

Published in:Proceedings of the European Conference on Antennas and Propagation

Published: 01/03/2019

Document VersionPeer reviewed version

Please cite the original version:Mollaei, M. S. M., Heydarian, R., Zanganeh, E., & Sedighy, S. H. (2019). Triple-Bands Ka-Band FrequencySelective Surface Filter with Different Polarized Transmitting Performance in Each Band. In Proceedings of theEuropean Conference on Antennas and Propagation [8740201] (Proceedings of the European Conference onAntennas and Propagation). IEEE. https://ieeexplore.ieee.org/document/8740201

© 2019 IEEE. This is the author’s version of an article that has been published by IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Triple-Bands Ka-Band Frequency Selective SurfaceFilter with Different Polarized Transmitting

Performance in Each Band

M. S. M. Mollaei1, R. Heydarian2, E. Zanganeh3, S. H. Sedighy4,1Department of Electronics and Nanothechnology, Aalto University, Espoo, Finland, Masoud.2.sharifianmazraehmollaei@aalto.fi*

2Department of Electrical Engineering, Guilan university, Rasht, Iran3Department of Electrical Engineering, Iran Universiry of Science and Technology, Tehran, Iran

4Department of New Technologies, Iran Universiry of Science and Technology, Tehran, Iran

Abstract—A triple-bands frequency selective surface (FSS)filter composed of combined enhanced Jerusalem and Gangbusterunit cells over square substrate integrated waveguide (SIW)cavities is presented. The enhanced Jerusalem cells produce twopass-bands with rotated polarization outputs while the enhancedGangbuster one produces one pass-band with same polarizedoutputs in comparison with the input wave polarization. Thepass-bands of the proposed FSS are at 33.5 GHz, 35.1GHz and36.8 GHz. The simulation results verify the proposed idea abilityand capability.

Index Terms—fss filter, polarization, SIW.

I. INTRODUCTION

For decades, frequency selective surfaces (FSSs) have at-tracted researchers due to their wide range of applications.The FSS filtering performance is used in many devices andsystems such as multi-beam antennas, large aperture antennas,satellite communication and Quasi-Optical systems [1]-[4]. Inthese applications, employing multi-band filters with differ-ent polarized outputs in each band leads to more compactstructure and cut the costs. In order to obtain pass bandpolarization rotator, first, a polarization rotator FSS for 900

polarization rotation has been introduced [4]; then, FSS filterswith arbitrary polarization rotation has been reported [5,6];however, an FSS filter with different polarization output canenhance the performance of aforementioned applications. Inthis paper, a triple-bands spatial filter FSS based upon substrateintegrated waveguide (SIW) cavities is presented. In order toobtain different amount of polarization rotation at each bandoutputs, enhanced Jerusalem and Gangbuster unit cells arecombined. Moreover, the square SIW cavities are employed toprevent overlap between current distributions of these surfaces.The enhanced Jerusalem unit cell produces two pass-bandswhich also rotate polarization of transmitted waves while theenhanced Gangbuster one produces one pass-band between theother two pass-bands related to the enhanced Jerusalem cell.

II. DESIGN PHILOSOPHY

Figure 1 shows the proposed triple-bands FSS structure. Thestructure unit cell includes four different SIW cavity sub cells.

The electromagnetic waves enter through the slots on the frontsurface of the SIW cavities in a specific frequency range andexcite it. Then, the excited cavities transmit the wave to theother side of structure by inserting slots on the back side of thestructure. The output polarization of each band is determinedwith respect to the angle between input and output slots.According to Fig. 1, the sub-cells which include the parallelinput and output slots perform as enhanced Gangbuster surfaceover SIW cavities and transmit the input wave to the outputwith similar polarization while the sub-cells which includethe orthogonal input and output slots perform as enhancedJerusalem surface over SIW cavities and transmit the waveswith rotated polarization. Beside one pass-band of enhancedGangbuster surface, enhanced Jerusalem surface with periodicdistance equal to wavelength between cells produces two pass-bands, also.

A. Design and Simulation

The slots, as input and output ports, play a key role in thestructure performance. Indeed, waves enter the SIW cavitiesthrough the slots and transmitted to the other side of thestructure through the back unit cell slots. With respect to thisfact, slots should be designed in a way that only the wavesin the desired frequency band can pass through them. As itwell known, the frequency resonance of a slot is dependedon its length where the following equations formulate thisrelationship [4]:

frs = c0/2l√εeff (1)

where c0 is the speed of light, l is the slot length and εeffstands for the substrate effective electric permittivity.

Alongside the slots, SIW cavities require careful designas the second type of resonators. In fact, decreasing overlapbetween current distributions of Gangbuster and JerusalemFSSs is the main reason of using SIW cavities. Moreover,in order to maximize the coupling between waves and cavity,the dominant mode of square SIW cavity needs to be excited.The following well known equation defines the relationship

Fig. 1. (a) The proposed FSS filter structure (b) unit-cell of the proposedfilter and its parameters (dashed slots are on the back side of the cavities).

between dimensions of square SIW cavity and its differentmodes resonance frequency [4]:

frc = (c0/2√εr)

√(m/Weff )2 + (n/Weff )2 + (p/h)2 (2)

Weff =W − d2/0.95b (3)

where W , d and b stand for the cavity length, vias diameterand distance between them, respectively, as shown in Fig.1. Moreover, SIW cavity structure only support (TMmn0)modes with m = 1, 2, 3, ... and n = 1, 2, 3, ... because SIWstructures are very thin and therefore permit no field variationin z-direction. When the resonance frequency of the slotsare equal to resonance frequency of the square SIW cavitydominant mode (TM110), the slot length is equal to the SIWcavity length which simply means that the slots cannot beinserted on the square SIW cavity. To address this problem,the enhanced square SIW cavity is employed. According to theperturbation theory, by adding a metallic object at the point

Fig. 2. The current distribution of dominant mode in square SIW cavity andthe appropriate position for input and output slots.

where the electric field of the mode is maximum, the resonancefrequency can be increased [7]. Considering this theory, firsta square SIW cavity with frequency resonance of dominantmode at 30 GHz is designed, and then by inserting a metallicvia at the center of square SIW cavity (maximum E filed atdominant mode), the frequency resonance of dominant modereaches to the intended frequency. Alongside the slots andsquare SIW cavity design, the slot positions on the square SIWcavity sides are important. The slot should be located wherethe distributed current arrows of dominant mode in the cavityare perpendicular to them to achieve more pure polarization.Figure 2 shows the current distribution of dominant mode insquare SIW cavities.

The proposed FSS structure is designed on Rogers RT/5880(1.57 mm thickness) substrate and simulated by CST Mi-crowave Studio. The presence of slots on square SIW cavitiesand their edge effects can create slight changes on the designparameters value achieved by equations (1) and (2). Theoptimized values for these parameters which shown in Fig. 1are tabulated in Table. The simulation results of the proposedFSS filter are plotted in Fig. 3. As it can be seen, the structureperforms as triple-band filter which its first and third pass-bands transmit waves with 90o polarization rotation (pertinentto the enhanced Jerusalem sub-cell) and its second pass-bandtransmit same polarized waves as incident waves (pertinentto the enhanced Gangbuster sub-cell). To clarify more, thestructure converts linear vertical polarization (because inputslots are horizontal) to both vertical and horizontal, but indifferent frequency bands.

Table: The optimized design values of the proposed FSSfilter.

Parameter W a d p l s t

Value (mm) 4.0 0.2 0.4 0.15 3.13 0.2 0.5

III. CONCLUSION

A triple-bands FSS filter with different polarized outputsin each band based on frequency selective surface over sub-strate integrated waveguide cavities has been presented in Kafrequency band. The proposed structure is constituted of theenhanced Jerusalem and Gangbuster surfaces over enhancedSIW cavities. Low cost, compact structure and design simplic-ity prove the ability and capability of the proposed structure.

Fig. 3. The simulation results of the proposed triple pass-bands FSS filter.

REFERENCES

[1] C. C. Huang and N. W. Chen, ”Frequency selective surface for reflectorantenna with multiple feeds,” 2012 IEEE Antennas and PropagationSociety International Symposium APSURSI, pp. 1-2, Chicago, Illinois,July. 2012.

[2] K. Sarabandi and N. Behdad, ”A frequency selective surface withminiaturized elements,” IEEE Trans. Antennas Propag., vol. 55, no. 5,pp. 1239-1245, May. 2007.

[3] M. S. M. Mollaei and A. H. Sedighy, ”Three bands substrate integratedwaveguide cavity spatial filter with different polarizations,” IEEE Trans.Antennas Propag., vol. 65, no. 10, pp. 5628-5632, Oct. 2017.

[4] S. A. Winkler, W. Hong, M. Bozzi and K. Wu, ”Polarization rotatingfrequency selective surface based on substrate integrated waveguidetechnology,” IEEE Trans. Antennas Propag., vol. 58, no. 4, pp. 1202-1213, Apr. 2010.

[5] M. S. M. Mollaei ”Narrowband configurable polarization rotator usingfrequency selective surface based on circular substrate-integrated waveg-uide cavity,” IEEE Antennas Wire. Propag. Lett., vol. 16, pp. 1923-1926,2017.

[6] M. S. M. Mollaei, E. Zanganeh and M. F. Farahani, ”Broadband Po-larization rotator for arbitrary angles with enhanced substrate integratedwaveguide cavities,” Int J RF Microw Comput Aided Eng., vol. 28, pp.21407, 2018.

[7] R. Harrington,Time-harmonic Electromagnetic Fields: New York: IEEEPress 2001.