A Large Frequency Ratio Shared-Aperture Antenna

Based on Structure Reuse

Jin Fan Zhang1, Yu Jian Cheng1, and Shu Han Liu2 1EHF Key Laboratory of Fundamental Science, School of Electronic Science and Engineering,

University of Electronic Science and Technology of China (UESTC), Chengdu, China

e-mail address: chengyujian@uestc.edu.cn 2Electrical and Computer Engineering department College of Engineering

University of California, Davis, California, 95616, USA

Abstract - This paper presents a new design of dual-band

shared-aperture antenna based on the concept of structure re-

use. The antenna consists of a patch antenna working at the 3.5 GHz and a 12×12 substrate integrated waveguide (SIW) slotted array antenna for the 60 GHz applications. In this design, the

overall structure of the SIW slotted array antenna is employed as a patch antenna unit operating at a lower frequency. With this new scheme, the high isolation and the high aperture reuse

efficiency between two antennas operated at different bands are achieved. The channel isolation between the patch and the SIW slot array antennas can be more than 130 dB at 3.5 GHz and 65

dB at 60 GHz. Both feeding networks and antennas are inte-grated together through the printed circuit boards (PCB) fabri-cation process.

Index Terms — Dual-band antenna, shared-aperture anten-na, structure reuse, large frequency ratio, millimeter-wave an-tennas, high aperture reuse efficiency, high isolation.

1. Introduction

The rapid development of the wireless communication

makes the sub-6G spectrum becomes more and more crowd-

ed. Thus, the millimeter-wave technology has attracted more

and more attention because of its rich spectrum resource to

support a faster data rate. However, it cannot replace these

microwave band wireless applications completely. Therefore,

the combination of the millimeter-wave technology and the

sub-6G technology is imperative in the next generation wire-

less communication system [1]. This means that the antenna

should be able to operate in the millimeter-wave and sub-6G

frequency bands simultaneously.

The large frequency ratio aperture-shared antenna is dif-

ferent from the small frequency ratio one. Some commonly

used array technologies, such as interlaced [2] and nested [3],

are difficult to realize due to the large difference in size be-

tween two antennas. In [4], different-band antennas are

placed separately, occupying a large space. The work in [5]

and use the overlapping technology to place different bands

of patches in different layers. However, there exists the prob-

lem of shade between two antennas, leading to the deteriora-

tion in radiation. It is difficult to achieve the high aperture

efficiency and isolation at the same time for a large frequen-

cy ratio shared-aperture antenna.

In this work, we propose a shared-aperture antenna based

on the concept of structure reuse. The antenna consists of a

patch antenna working for the 3.5 GHz and a 12×12 sub-

strate integrated waveguide (SIW) [6] slotted array antenna

for the 60 GHz applications. The reuse of the structure can

greatly reduce the desired area to place these antennas. The

performances of two antennas operated at different bands can

be maintained without deterioration. The cut off characteris-

tic of the SIW [7]-[11] and the enclosed con figuration in-

crease the isolation at 3.5GHz. The isolation at 60GHz is

improved by introducing a compact microstrip resonance cell.

Fig. 1. Exploded view of the proposed antenna.

Fig. 2. Profile of the proposed antenna.

2. Antenna Design

The proposed antenna is shown in Fig. 1. It is designed on

three substrate layers, i.e. Sub. 1, Sub. 2 and Sub. 3, as

shown in Fig. 2. The 12×12 SIW slotted array antenna is on

Sub. 1. A 12-way comb likely SIW power divider is de-

signed to feed 12 linear SIW slot arrays, and each of them

carries 12 radiation slots etched on the broad wall of the SIW.

The patch antenna is composed of the first and second

conductor layers connected by metalized via holes. The third

conductor layer is used as the ground, and the slot on the

shorted-circuit structure of the patch to adjust the center fre-

[WeF2-5] 2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea

137

quency from 3.2 GHz to 3.5 GHz. The size of antenna is 32

mm×37.7 mm×2.6 mm.

Fig. 3. Gain and S-parameter at different frequency bands.

Fig. 4. Radiation patterns at different frequency bands.

TABLE I

Comparison of Different Shared-Aperture Antennas

Frequen-cy ratio

Array

Isolation (dB) at lower and higher bands

Reuse ratio

[4] 10 No / Yes < -20 / < -40 0

[5] 40 No / Yes < -60 / < -60 0.25

[12] 10 No/No < -95 / < -25 <0.25

This work 17 No / Yes < -130 / < -65 0.77

3. Design Results

This shared-aperture antenna is designed using the HFSS

15. Fig. 3 shows the simulated and measured reflection coef-

ficient and gain at different frequency bands. The measured

peak gain of the slot array antenna and patch antenna are

24.0 dBi and 7.3dBi, respectively. The measured impedance

bandwidth (S11<−10 dB) at different frequency bands are

6.4% (58.6~62.5 GHz) and 2.6% (3.43~3.52 GHz). The

measured isolation between two ports within the frequency

range from 58 GHz to 61 GHz is better than 65 dB. Fig. 4

shows the radiation patterns in the E-plane and H-plane.

The performance comparison among different shared-

aperture antennas is given in Table I. Here, the reuse ratio of

a shared-aperture antenna can be defined by Sr /S. S repre-

sents the area occupied by the larger radiation structure oper-

ated. Sr is the occupied area of the other radiating structure.

4. Conclusion

A new design of a dual-frequency antenna is presented in

this paper. The patch and the SIW slotted array share the

same radiation aperture with high aperture reuse efficiency.

Their radiation abilities are unchanged compared with con-

ventional single-band designs. High isolation between the

two bands can be achieved.

Acknowledgment

This work is supported in part by the National Natural Sci-

ence Foundation of China (NSFC) under grants 61631012

and 61871088.

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2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea

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