In order to achieve wide bandwidth and high gain, we propose a stacked antenna structure having a microstrip aperture coupled feeding technique with a mounted Horn integrated on it. With optimized parameters, the single antenna element at a center frequency of 60 GHz, exhibits a wide impedance bandwidth of about 10.58% (58.9–65.25 GHz) with a gain and efficiency of 11.78 dB and 88%, respectively. For improving the gain, we designed a 2 × 2 and 4 × 4 arrays with a corporate feed network. The side lobe levels were minimized and the back radiations were reduced by making use of a reflector at
Soon after the development of 60 GHz standard that provides a 7 GHz license-free bandwidth worldwide, its popularity became evident at millimeter waves spectrum due to its usage in high data-rate wireless communications at gigabit per second [
In any radio communication or wireless systems, antenna plays a vital part [
In this paper, a stacked microstrip antenna utilizing aperture-coupled technique with a mounted Horn on FR-4 substrate is presented, at a center frequency of 60 GHz. By employing this technique, a wide impedance bandwidth of about 10.58% (58.9–65.25 GHz) is achieved with high gain and efficiency. The gain and efficiency of the single element antenna are further increased by presenting a corporate fed network of 2 × 2 and 4 × 4 arrays. The 2 × 2 array structure resulted in improved gain of 15.3 dB with efficiency of 83%. While the 4 × 4 array structure provided further gain improvement of 18.07 dB with 68.3% efficiency. This paper is an extended work of our previous results [
The geometry of the single antenna element is shown in Figure
Parameters of proposed antenna in mm.
Design | Antenna element | Dimensions/parameters |
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Layer I | Microstrip feed | Feed width, |
Thickness, |
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Stub length, |
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Substrate | RT Duroid 5880 | |
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Width, |
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Thickness, |
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Ground | Thickness, |
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Length |
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Width |
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Thickness, |
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Rectangular slot | Slot length, |
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Slot width, |
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Layer II | Substrate | RT Duroid 5880 |
Thickness, |
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Length, |
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Width, |
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Patch | Length, |
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Width, |
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Layer III | Substrate | FR 4 |
Thickness, |
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Cut in FR-4 | Length, |
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Width, |
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Horn | Horn dimensions | Horn length |
Horn width, |
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Waveguide length, |
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Waveguide width, |
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Thickness of metal horn, |
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Full structure | Total height | 4 |
Exploded view of proposed multilayer ACMPA with mounted Horn.
With the aid of simulation tools, the proposed multilayer antenna was numerically optimized and the results were obtained. The objective was to achieve a wide bandwidth, high gain, and efficiency. Compared to [
Comparison of return loss and gain.
Figures
(a) Simulated E-plane radiation pattern at 59, 62, and 65 GHz and (b) simulated H-plane radiation pattern at 59, 62, and 65 GHz.
Limited methods exist in analyzing the antenna arrays. In the existing methods, arrays factor is the easiest one among others [
The array factor depends only on the geometry of the array and the phase between each element. The actual radiator then replaces each point and the far field radiation pattern is determined by pattern multiplying the array factor with the pattern of the radiator. Mutual coupling is ignored in the process since the radiators are treated separately; also their influences on each other are not considered. Since we are working on improving the gain of the antenna, therefore, the mutual coupling cannot be ignored and the results deduced by array factor must be modified.
The next step is to improve the gain by making use of 2 × 2 and 4 × 4 arrays. The 3D exploded view of the 2 × 2 arrays structure is shown in Figure
Exploded view of 2 × 2 multilayer array with
A corporate feed network connected to a 50 Ω line was used as power division between antenna elements. Corporate feed networks are in general very versatile as they offer power splits of
Corporate-feed network for 2 × 2 array.
Analyzing the top half of feed network shown in Figure
Lengths and widths of 50 Ω and 70.7 Ω feeds.
Transmission line | Width (mm) | Length (mm) |
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50 Ω | 0.386 | 1.07 |
70.7 Ω | 0.2262 | 0.93 |
The proposed antenna of 2 × 2 array was simulated via simulation tools. Figure
Modified antenna parameters.
Parameters | 2 × 2 array | 4 × 4 array |
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Patch length, |
1.25 | 1.25 |
Patch width, |
1.25 | 1.25 |
Stub length, |
0.45 | 0.45 |
Horn length, |
12 | 12 |
Horn width, |
18 | 20 |
Return loss and gain of 2 × 2 array.
The E-plane and H-plane radiation patterns, simulated in CST and HFSS, for 2 × 2 array structure at frequencies 59, 62, and 65 GHz are shown in Figures
(a) E-plane radiation pattern at 59, 62, and 65 GHz for 2 × 2 array and (b) H-plane radiation pattern at 59, 62, and 65 GHz for 2 × 2 array.
Similarly, the 4 × 4 array was simulated and the comparison of results in terms of return loss and gain is shown in Figure
Simulated results of single element and 2 × 2 and 4 × 4 arrays.
Array/parameters | Single element | 2 × 2 array | 4 × 4 array |
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Bandwidth | 10.58% | 10.55% | 10.51% |
Gain | 11.78 dB | 15.3 dB | 18.07 dB |
Efficiency | 88% | 83% | 68.3% |
Return loss and gain of 4 × 4 array.
(a) E-plane radiation pattern at 59, 62, and 65 GHz for 4 × 4 array and (b) H-plane radiation pattern at 59, 62, and 65 GHz for 4 × 4 array.
A high gain and wide band multilayer antenna for 60 GHz are proposed in this paper. Stacked structure technique employing aperture coupled feeding with mounted Horn antenna is employed as the radiator for the single element, 2 × 2 and 4 × 4 arrays. The proposed antenna exhibits a broad impedance bandwidth of about 10.5% (58.9–65.25 GHz). Comprised by the proposed antenna element, an antenna array is investigated. Simulated results in CST and HFSS show that the antenna array realized provides a maximum gain and efficiency of 18.07 dB and 68.3%, respectively. The proposed antenna finds application in V-band communication systems.
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors would like to thank the Deanship of Scientific Research, Research Center at College of Engineering, King Saud University, for funding.