диафрагмированные волноводные фильтры / 38b617d8-d77b-46e0-9b8e-193180ea2dab

Abstract—In this paper, a novel design of slotted waveguide array filtering antenna is proposed. By integrating a pair of waveguide bandpass filters with the slotted waveguide array antenna, the integrated design not only exhibits a high gain, but also offer a good filter response. For demonstration, an antenna prototype with a center frequency of 10 GHz is designed and simulated. The simulated results show a fractional bandwidth of 7.4% covering from 9.526 to 10.39 GHz, and a high gain of 17.1 dBi.

Keywords—array; broadband width; filter; slot antenna

I.INTRODUCTION

With the significant advancement of wireless technology for the past years, compact devices integrated with multi-function have become the main trend in the wireless communication devices. Microwave filter and antenna are vital devices in modern communication systems. Generally, they are independently designed and can be cascaded to work together when necessary. However, the direct cascade of filter and antenna often results in an impedance mismatch and performance deterioration of RF components. In recent years, filtering antenna has drawn a lot of attention of scholars due to its characteristics of achieving filtering and radiation simultaneously. Such device can be realized by integrating filter and antenna into a single unit. And it is designed following the synthesis process [1], [2].

On the other hand, slotted waveguide array antenna is one of the most popular antennas in communication systems. It has advantages of simple configuration, easy fabrication, high radiation efficiency and steady performance, which make it very attractive for applications like radar, communication, and navigation. In the past years, there has been many researches conducting this type of antenna [3], [4], but few researched have been done to design the antenna with filter response. In this paper, a novel slotted waveguide array filtering antenna is proposed. Its design process and simulation are presented in the following sections.

II. FILTERING ANTENNA DESIGN

The proposed slotted waveguide array filtering antenna consists of slotted array antenna, waveguide filter and E-plane power divider. In order to simplify its design, the antenna and filter are designed separately. And then they are combined together with the integrated power divider to form a filtering antenna.

A. The slotted waveguide array antenna

Fig. 1(a) shows the configuration of the designed slotted array antenna, which is composed of ten uniform elements. The waveguide antenna is fed from the waveguides on both sides with anti-phase signal. Thus, a virtual short will be generated in the symmetrical plane, and further the ten elements array can be split into a couple of five elements sub-arrays. This designed feeding mechanism can effectively increase the bandwidth of the antenna compared with that fed by one side. The EM optimization of this antenna is carried out by using HFSS 15. The critical dimensions shown in Fig. 1(a) are: ld = 19.87, la = 14.44, wa = 2.3, tr = 2 (all in millimeters). The simulated return loss is shown in Fig. 1(b).

Frequency (GHz)

(b)

Fig. 1. (a) Geometry of slotted waveguide array antenna. (b) its return loss.

B. The fourth oder Chebyshev filter

The configuration of the waveguide bandpass filter is shown in Fig. 2(a). It consists of four coupled rectangular resonators operating in the TE101 mode and a pair of feed waveguides. The input/output coupling and the coupling between adjacent resonators are realized by using inductive irises. The filter is designed with a center frequency of 10 GHz, a fractional bandwidth of 7.4% and a passband return loss of 20 dB. According to the coupling matrix theory that described in [5]. The external Q and the non-zero coupling coefficients can be

obtained as fellows: Qe1 = Qe4 = 10.85, M12 = M34 = 0.078, and M23 = 0.06. The critical dimensions shown in Fig. 2(a) are a =

22.86, b = 10.16, w1 = w5 = 13.92, w2 = w4 = 10.61, w2 = 9.86, l1 = l4 = 16.72, l2 = l3 = 19.06, and wf = 4 (all in millimeter). Fig.

2(b) shows the simulated return loss of the filter.

Frequency (GHz)

(b)

Fig. 2. (a) Geometry of the waveguide filter. (b) Its S-parameters.

III. SIMULATED RESULTS

By combining the previous designed slotted waveguide antenna and filter together with integrated E-plane power divider, Fig. 3 shows the geometry of the proposed filtering antenna. The simulation was performed using EM simulator HFSS 15. Fig. 4 shows the simulated return loss of the filtering antenna in comparison with that of previous designed antenna and filter. It can be seen that the filtering antenna exhibits a good filter response with high out of band rejection, thus avoiding

Fig. 3. Geometry of the proposed filering antenna.

Fig. 4. Return losses performance of the filtering antenna, antenna and filter.

radiation at out of band frequencies that is true for the antenna without integrated filter (the dashed red line). The impedance bandwidth of the filtering antenna with return loss better than 10 dB is ranging from 9.57 to 10.43 GHz, which corresponds to a fractional bandwidth of 7.4%. The simulated E-plane radiation patterns and H-plane at 10 GHz frequencies are illustrated in Fig. 5. As can be seen, the proposed filtering antenna displays a high gain and low sidelobe levels, where the gain can achieve 17.1dBi.

(a)

Fig. 5. (a) Three-dimensional radiation patterns. (b) Two-dimensional E-Plane radiation patterns. (c) Two-dimensional H-Plane radiation patterns.

IV. CONCLUSION

A slotted waveguide array filtering antenna has been designed in this paper. The design consists of slotted array antenna, waveguide filter and E-plane power divider. It can achieve a high gain and good filter response simultaneously. The antenna has potential to be applied in modern communication systems.

REFERENCES

[1]C. Chuang, S. Chung, “Synthesis and design of a new printed filtering antenna,” IEEE Trans. Antennas. Propagat, vol. 59, no. 3, pp.1036–1042, January 2011.

[2]W.-J. Wu, Y.-Z. Yin, S.-L. Zuo, Z.-Y. Zhang, and J.-J. Xie, “A new compact filter-antenna for modern wireless communication systems,” IEEE Antennas Wireless Propag. Lett., vol. 10, pp. 1131–1134, October 2011.

[3]S.-Y. Chen, P. Hsu, “Broad-band radial slot antenna fed by coplanar waveguide for dual-frequency operation,” IEEE Trans. Antennas. Propagat vol. 53, no. 11, pp.3448–3452, November 2005.

[4]A. Vosoogh, A. Haddadi, A. Zaman, “W-Band Low-Profile Monopulse Slot Array Antenna Based on Gap Waveguide Corporate-Feed Network,” IEEE Trans. Antennas. Propagat vol. 66, no. 12, pp.6997–7009, December 2018.

[5]J. Hong, M. J. Lancaster, “Microstrip filters for RF/microwave applications,” Wiley, New York