**7.2 Stacked microstrip antenna with SRR**

Stacked microstrip patches antennas with and without SRR has been designed, see Refs. [1–5]. The antennas was designed on the same substrate. The antennas are stacked double-layer antennas. The first layer consists of a FR4 substrate with a dielectric constant of 4.2 and 1.6 mm thickness. The second layer consists of a dielectric substrate with a dielectric constant of 2.3 and 1.6 mm thickness. The antenna has been analyzed and optimized by using full wave electromagnetic software. The dimensions of the microstrip stacked patch antenna are 33 20 3.2 mm as presented in **Figure 25**. The antenna bandwidth is around 6% for VSWR better than 3:1. The antenna beam width is around 74°. The stacked antenna directivity and gain are around 7 dBi. The computed S11 parameters are presented in **Figure 26**. Radiation pattern of the microstrip stacked patch is shown in **Figure 27**. The stacked patch antenna with SRR is presented in **Figure 28**. This antenna has the same structure as the stacked antenna shown in **Figure 25**. The spacing between the SRR rings is 0.25 mm and the ring width is 0.2 mm. Four rows of seven SRRs are placed on the radiating patch. The measured S11 parameters of the antenna with SRR are presented in **Figure 29**. The antenna bandwidth is around 13% for VSWR better than 2.5:1. By adding an air space of 4 mm between the antenna layers, the VSWR was improved to 2:1. The antenna gain is around 9–10 dBi. The antenna's

**Figure 25.** *A microstrip stacked patch antenna.*

**Figure 26.** *Computed S11 of the microstrip stacked patch.*

**6.1 Rat-race coupler**

**Figure 24.** *Rat-race coupler.*

**applications**

**7.1 Introduction**

**38**

A rat-race coupler is shown in **Figure 24**. The rat-race circumference is 1.5 wavelengths. The distance from A to **Δ** port is 3λ\4. The distance from A to P port is λ\4. For an equal-split rat-race coupler, the impedance of the entire ring is fixed at 1.41 Z0, or 70.7 Ω for Z0 = 50 Ω. For an input signal V, the outputs at ports 2 and

*Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

Low profile efficient antennas are crucial in the development of commercial compact 5G communication and IoT systems. Communication, IoT, and biomedical industries are in rapid growth in the last years. It is important to develop efficient high gain compact antennas for 5G communication and IoT systems. Metamaterials and fractal structures may be used to improve the efficiency of compact printed

Small printed antennas suffer from low efficiency. Metamaterial technology is used to design wearable compact antennas with high efficiency. The metamaterial antennas may be used in 5G communication systems, IoT, and medical systems. Design trade-offs, development, and computed and measured results of compact, efficient metamaterial antennas are presented in this chapter. The gain and directivity of the patch antenna with split ring resonators (SRRs) are higher by 2.5 dB than the patch antenna without SRR. The resonant frequency of the antenna with SRR on human body is shifted by 3%. Printed antennas are used in communication systems and are presented in journals and books, as referred in [1–5]. Microstrip and printed antennas have several advantages such as being light weight, compact, flexible, and having low production cost. The main disadvantages of these printed antennas are narrow bandwidth and low efficiency. In Ref. [51], artificial media with negative dielectric permittivity were presented. Materials with dielectric constant and permeability less than 1 are developed by using periodic SRR and metallic posts structures as presented in [51–59]. New wearable printed metamaterial

4 are equal in magnitude, but 180 degrees out of phase.

**7. Wearable Metamaterial antennas for 5G, IoT, and medical**

antennas. In this chapter metamaterial antennas will be presented.

antennas with high efficiency are presented in this chapter.

**Figure 27.** *Radiation pattern of the microstrip stacked patch.*

#### **Figure 28.**

*Printed antenna with split ring resonators.*

efficiency is around 95%. The antenna computed radiation pattern is shown in **Figure 30**. There is a good agreement between the measured and computed results. The effective area of a patch antenna without SRR is lower than the effective area of a patch antenna with SRR. The resonant frequency of a patch antenna without SRR is higher by 10% than the resonant frequency of a patch antenna with SRR. The antenna beamwidth is around 70°. The directivity and gain of the stacked antenna with SRR is higher by 2–3 dB than the patch antenna without SRR.

**7.3 Patch antenna with split ring resonators**

*Radiation pattern for patch with SRR for medical and 5G applications.*

*Patch with split ring resonators for medical and 5G applications, measured S11.*

*Wideband Wearable Antennas for 5G, IoT, and Medical Applications*

*DOI: http://dx.doi.org/10.5772/intechopen.93492*

**Figure 29.**

**Figure 30.**

**41**

A patch antenna with split ring resonators was developed. The antenna is printed on the dielectric substrate with a dielectric constant of 2.2 and with a 1.6 mm thickness. The dimensions of the microstrip patch antenna shown in

#### *Wideband Wearable Antennas for 5G, IoT, and Medical Applications DOI: http://dx.doi.org/10.5772/intechopen.93492*

**Figure 29.** *Patch with split ring resonators for medical and 5G applications, measured S11.*

**Figure 30.** *Radiation pattern for patch with SRR for medical and 5G applications.*

#### **7.3 Patch antenna with split ring resonators**

A patch antenna with split ring resonators was developed. The antenna is printed on the dielectric substrate with a dielectric constant of 2.2 and with a 1.6 mm thickness. The dimensions of the microstrip patch antenna shown in

efficiency is around 95%. The antenna computed radiation pattern is shown in **Figure 30**. There is a good agreement between the measured and computed results. The effective area of a patch antenna without SRR is lower than the effective area of a patch antenna with SRR. The resonant frequency of a patch antenna without SRR is higher by 10% than the resonant frequency of a patch antenna with SRR. The antenna beamwidth is around 70°. The directivity and gain of the stacked antenna

*Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

with SRR is higher by 2–3 dB than the patch antenna without SRR.

**Figure 27.**

**Figure 28.**

**40**

*Printed antenna with split ring resonators.*

*Radiation pattern of the microstrip stacked patch.*

### *Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

patch antenna with SRR is higher by 2.5 dB than the patch antenna without SRR. A photo of printed metamaterial antennas for medical and IoT applications is shown in **Figure 33**. Metamaterial patch antenna with SRR for 5G, IoT, and medical

*Wideband Wearable Antennas for 5G, IoT, and Medical Applications*

*DOI: http://dx.doi.org/10.5772/intechopen.93492*

**Figure 33.**

**Figure 34.**

**Figure 35.**

**43**

*Photo of metamaterial patch antenna with SRR.*

*Meta-material stacked patch antenna with SRR.*

*Photo of printed metamaterial antennas for medical applications.*

**Figure 31.** *Patch antenna with 15 Split ring resonators.*

**Figure 32.** *Patch with 15 split ring resonators, computed S11.*

**Figure 31** are 36 20 1.6 mm. The metamaterial antenna bandwidth is around 6% for VSWR better than 2:1. The antenna bandwidth is around 9% for S11 lower than 6 dB. The antenna directivity and gain are around 7.5 dBi. The computed and measured antenna beam width is around 72°. The antenna efficiency is 77.25%. The measured S11 parameters are presented in **Figure 32**. The gain and directivity of the patch antenna with SRR is higher by 2.5 dB than the patch antenna without SRR. A photo of printed metamaterial antennas for medical and IoT applications is shown in **Figure 33**. Metamaterial patch antenna with SRR for 5G, IoT, and medical

**Figure 33.** *Photo of printed metamaterial antennas for medical applications.*

**Figure 34.** *Photo of metamaterial patch antenna with SRR.*

**Figure 35.** *Meta-material stacked patch antenna with SRR.*

**Figure 31** are 36 20 1.6 mm. The metamaterial antenna bandwidth is around 6% for VSWR better than 2:1. The antenna bandwidth is around 9% for S11 lower than 6 dB. The antenna directivity and gain are around 7.5 dBi. The computed and measured antenna beam width is around 72°. The antenna efficiency is 77.25%. The measured S11 parameters are presented in **Figure 32**. The gain and directivity of the

*Advanced Radio Frequency Antennas for Modern Communication and Medical Systems*

**Figure 31.**

**Figure 32.**

**42**

*Patch antenna with 15 Split ring resonators.*

*Patch with 15 split ring resonators, computed S11.*

applications is shown in **Figure 34**. Metamaterial stacked patch antenna with SRR for 5G, IoT, and medical applications is shown in **Figure 35**.

**References**

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*DOI: http://dx.doi.org/10.5772/intechopen.93492*

*Wideband Wearable Antennas for 5G, IoT, and Medical Applications*

Transactions on Biomedical

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[13] Salonen P, Rahmat-Samii Y, Kivikoski M. Wearable antennas in the vicinity of human body. In: IEEE Antennas and Propagation Society Symposium, Vol. 1, Monterey USA,

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[12] Thalmann T, Popovic Z, Notaros BM, Mosig JR. Investigation and design of a multi-band wearable antenna. In: 3rd European Conference on Antennas and Propagation. Berlin, Germany: EuCAP

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[2] Sabban A. Novel Wearable Antennas for Communication and Medical Systems. FL, USA: Taylor & Francis

[3] Sabban A. Low Visibility Antennas for Communication Systems. USA: Taylor & Francis Group; 2015

[4] Sabban A. Small wearable meta materials antennas for medical systems. The Applied Computational Electromagnetics Society Journal. April

[5] Sabban A. Microstrip antenna arrays. In: Nasimuddin N, editor. Microstrip Antennas. Croatia: InTech; 2011. pp. 361-384. ISBN: 978-953-307-247-0. Available from: http://www.intechopen. com/articles/show/title/microstrip-

[6] Sabban A. New wideband printed antennas for medical applications. IEEE

[7] Sabban A. Dual polarized dipole wearable antenna. USA: U.S Patent

[8] Sabban A. A new wideband stacked microstrip antenna. In: IEEE Antenna and Propagation Symposium. Houston,

[9] Sabban A. Wideband microstrip antenna arrays. In: IEEE Antenna and Propagation Symposium MELCOM,

[10] Chirwa\* Lawrence C, Hammond Paul A, Scott Roy Cumming David RS. "Electromagnetic radiation from ingested sources in the human intestine between 150 MHz and 1.2 GHz", IEEE

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