Design and realization of dual band microstrip siw antenna

Abstract

Keywords: Microstrip antenna; X band; K band; substrate integrated wavequide; SIW; radar.

1. Introduction

The need of antenna design with low-cost, low-profile, broadband or multi band specs has become a very important research topic for microwave engineers [1-3]. One of the most commonly used antenna model for antenna design with the mentioned specs, is microstirp patch antennas. For the last few decades there had been many studies on design and realization of dual band micrsotirp patch antennas [4-12]. However the traditionally microstirp patch antenna design also suffers from the disadvantages such as narrow operation band, low directivity or waveguide loss. Substrate-Integrated Waveguide (SIW) is a novel and efficient solution counterpart of the traditionally waveguide designs [13–14]. Since a SIW structure can easily realized on a planar substrate, its integration with other planar microwave systems is possible. Also compare to a traditionally microstrip resonator, the SIW resonator can achieve a higher Q factor [15]. Recently, Antenna designs with SIW technology are becoming a trending topic for novel, high performance antenna design [16-20]. Antennas designed with SIW technology have excellent performance due to the ability of suppressing surface wave propagation, wider operation band, decreased end-fire radiation and cross-polarization radiation. High performance antenna designs have a very wide application range such as satellite communication, and radar. In this *

Corresponding Author: e-mail: aysu.yldrm07@gmail.com, tel: (212) 383 58 81 305

work, SIW technology is applied to design a dual-band antenna for X and K Band Radar applications. Firstly, a novel SIW antenna is designed in CST Microwave Studio for 10 & 24GHz band application and prototyped on Rogers 4350. The simulated and measured performance results of the design is compared. As a result, it can be concluded that, the proposed model is a sufficient and low-cost solution for X and K band radar applications.

2. Design Procedure Of SIW Antenna

In SIW design by using rows of metallized via’s through the dielectric substrate material it is possible to form walls for confining both electric and magnetic waves. Moreover the conductive layers both in top and ground layer of the microstrip substrate would provide two additional waveguide walls. Vias

Figure 1. Schematic of a SIW structure. In the procedure of SIW design there are important parameters that their values should determine wisely such as, (i) Dielectric constant of the substrate: effects the radiation efficiency and the bandwidth of the operation frequency of the design. For achievement of wide impedance bandwidth a low dielectric constant is required. (ii) Metallized via arrays, the total number of via’s and their gaps are plays an important role for building the side- walls of SIW structures. In the next section by using the SIW technology, the design procedure and schematic of a high performance dual band antenna has been presented.

3. Study Case

The proposed dual band SIW antenna model is given in Fig. 2 alongside of its parametric design layout and optimally selected parameters value in Table 1. The values of parameters given in Table 1, are obtained via trial and error alongside of local optimization process of CST studio Environment to achieve high performance for both X and K band applications. The proposed antenna is modelled and fabricated (Fig. 3) on Rogers’s 4350 high performance substrate the simulation and measurement results of the proposed SIW antenna are given in the next section Figs. 4-6 and Table 2. W1

Figure 2. (a) Antenna geometry, (b) Parametric layout of SIW antenna. 306

The measurement results are obtained using the measurement setup given in Fig. 3. The antennas given in [21] are used for measurements at 1-18 GHz and 18-30 GHz respectively. As it can be seen from the measurement results, the proposed SIW antenna achieves a return loss characteristics of less than -15 dB at 10 & 22 GHz and a gain level of almost 6 & 7.2 dBi. Although, there is a frequency shift at the secondary band due to the manufacturing errors, antenna still achieves a high performance. A detailed performance measurement of the prototyped antenna compared to counterpart designs with and without SIW structure has been given in Table 2. Furthermore, a comparison of the proposed antenna with counterpart design in literature had been presented in Table 3.

Figure 3. (a) Fabricated antenna (b) Measurement setup [22].

(b) Figure 4. Simulated Gain Patterns (a) @10GHz, (b) @24GHz

Figure 6. Gain measurement (a) 10GHz (b) 22GHz. Table 2. Comparison of Realized Gain Model Siw Meas Siw Sim No Siw No Siw Opt

Realized Gain dB 10GHz 22GHz 6 7.2 6.2 7.6 2.82 6.46 3.58 7.5

Substrate Roger 4350 --Arlon 25N Taconic TLY Roger-Droid 5880

4. Conclusion

In this paper, a novel high-gain planar SIW antenna had been proposed for X and K band applications. By using, SIW technology on microstrip patch antenna an easy and cost-effective fabrication is achieved. As it can be seen from simulation and measurement results, the proposed novel high-gain planar SIW antenna for X and Ka band applications is a suitable candidate for RADAR application that require an enhanced-gain performance. The performance of the proposed antenna design had been verified with its simulation and measurement results.

Acknowledgment

We would like to express our special thanks of gratitude to the Aktif Neser Elektronik, for providing researcher license of CST, Microwave and Antenna Laboratory of Yıldız Technical University. This work was supported by 100/2000 YÖK and TÜBİTAK-BİDEB 2011/A International PhD Fellowship Programme.

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