**4. Wideband MM-Wave Couplers**

Couplers are used to couple part of the power in the input port to a coupled port. For example, as presented in **Figures 8** and **9**. Usually couplers consist of two coupled quarter-wavelength transmission lines and have four ports, as shown in

**Figure 31**. P1 is the input port, P2 is the transmitted port, P3 is the coupled port, and P4 is the isolated port. The coupled port may be used to obtain the information about the signal such as frequency and power level without interrupting the main power flow in the device. The coupling factor may be calculated by using Eq. (1) and is the ratio between the coupled power to the input power in dB when the other ports are terminated. Coupler losses may be calculated using Eq. (2). The overall

**Figure 22.**

**Figure 23.**

**41**

*SFB S12 computed results.*

*a. S11 SBF computed results; b. S21 SBF computed results.*

*Ultra-Wideband MM Wave System and RF Modules DOI: http://dx.doi.org/10.5772/intechopen.97853*

*Ultra-Wideband MM Wave System and RF Modules DOI: http://dx.doi.org/10.5772/intechopen.97853*

**Figure 22.** *a. S11 SBF computed results; b. S21 SBF computed results.*

**Figure 23.** *SFB S12 computed results.*

**Figure 31**. P1 is the input port, P2 is the transmitted port, P3 is the coupled port, and P4 is the isolated port. The coupled port may be used to obtain the information about the signal such as frequency and power level without interrupting the main power flow in the device. The coupling factor may be calculated by using Eq. (1) and is the ratio between the coupled power to the input power in dB when the other ports are terminated. Coupler losses may be calculated using Eq. (2). The overall

**4. Wideband MM-Wave Couplers**

**Figure 20.**

**Figure 21.** *SFB analysis results.*

**40**

*S parameters for filter #3.*

*Innovations in Ultra-WideBand Technologies*

Couplers are used to couple part of the power in the input port to a coupled port.

For example, as presented in **Figures 8** and **9**. Usually couplers consist of two coupled quarter-wavelength transmission lines and have four ports, as shown in

**Figure 24.** *SFB layout.*

**Figure 25.** *SFB picture.*

coupler losses are due to conductor losses, coupling losses, dielectric losses, radiation losses, and matching losses.

$$\text{Cooupling Factor} = \text{CF} = -10 \log \frac{\text{P3}}{\text{P1}} \tag{1}$$

**Figure 26.**

**Figure 27.**

**Figure 28.**

**43**

*SFB measured S12 results.*

*Measured S parameters for filter #2.*

*SFB measured results unit number 1.*

*Ultra-Wideband MM Wave System and RF Modules DOI: http://dx.doi.org/10.5772/intechopen.97853*

$$\text{Inversion Loss} = IL = 10 \log \left( 1 - \frac{\text{P3}}{\text{P1}} \right) \tag{2}$$

The isolation factor is the ratio between the power in the isolated port to the input power in dB when the other ports are terminated and is given by Eq. (3).

$$\text{Isolation} = -10 \log \frac{\text{P4}}{\text{P1}} \tag{3}$$

*Ultra-Wideband MM Wave System and RF Modules DOI: http://dx.doi.org/10.5772/intechopen.97853*

**Figure 26.** *SFB measured results unit number 1.*

**Figure 27.** *Measured S parameters for filter #2.*

**Figure 28.** *SFB measured S12 results.*

coupler losses are due to conductor losses, coupling losses, dielectric losses,

*Coupling Factor* <sup>¼</sup> *CF* ¼ �<sup>10</sup> *log* P3

*Insertion Loss* <sup>¼</sup> *IL* <sup>¼</sup> 10 log 1 � P3

The isolation factor is the ratio between the power in the isolated port to the input power in dB when the other ports are terminated and is given by Eq. (3).

*Isolation* ¼ �<sup>10</sup> *log* P4

P1 (1)

P1 (3)

(2)

P1 

radiation losses, and matching losses.

*Innovations in Ultra-WideBand Technologies*

**Figure 25.** *SFB picture.*

**42**

**Figure 24.** *SFB layout.*

The coupler directivity is the ratio between the power in the isolated port to the coupled power in dB when the other ports are terminated and is given by Eq. (4).

*Directivity* <sup>¼</sup> *<sup>D</sup>* ¼ �<sup>10</sup> *log* P4

phase balance between the system ports determines the accuracy of the signal processing process. The power difference in dB between two output ports of the system is defined as the amplitude balance. In an ideal hybrid circuit, the amplitude difference between two ports should be 0 dB. The phase difference in degrees between two output ports of the system is defined as the phase balance. However,

in real life the amplitude balance and phase balance vary with frequency.

dielectric constant and 5.5 mil-inch thickness. The coupler frequency range is 18 GHz to 40 GHz. The coupler was designed by Momentum ADS software. The coupling value is �13 dB and is shown in **Figure 33**. The coupler insertion loss is 0.4 dB and is shown in **Figure 34**. The coupler S11 parameter is better than �26 dB

**4.1 A wideband MM-wave coupler**

*Ultra-Wideband MM Wave System and RF Modules DOI: http://dx.doi.org/10.5772/intechopen.97853*

*18 GHz to 40 GHz, wideband MM-wave coupler.*

*The wideband coupler coupling value, S12.*

and is shown in **Figure 35**.

**Figure 32.**

**Figure 33.**

**45**

In radars, DF systems, seekers, and communication systems, the amplitude and

**Figure 32** presents a wideband MM-wave coupler printed on alumina with a 9.8

P3 (4)

**Figure 29.** *SFB measured S11 results.*

**Figure 30.** *SFG detailed measured S12 results.*

**Figure 31.** *Coupled lines.*

*Ultra-Wideband MM Wave System and RF Modules DOI: http://dx.doi.org/10.5772/intechopen.97853*

The coupler directivity is the ratio between the power in the isolated port to the coupled power in dB when the other ports are terminated and is given by Eq. (4).

$$\text{Directivity} = D = -\mathbf{1}0 \log \frac{\mathbf{P4}}{\mathbf{P3}} \tag{4}$$

In radars, DF systems, seekers, and communication systems, the amplitude and phase balance between the system ports determines the accuracy of the signal processing process. The power difference in dB between two output ports of the system is defined as the amplitude balance. In an ideal hybrid circuit, the amplitude difference between two ports should be 0 dB. The phase difference in degrees between two output ports of the system is defined as the phase balance. However, in real life the amplitude balance and phase balance vary with frequency.

## **4.1 A wideband MM-wave coupler**

**Figure 32** presents a wideband MM-wave coupler printed on alumina with a 9.8 dielectric constant and 5.5 mil-inch thickness. The coupler frequency range is 18 GHz to 40 GHz. The coupler was designed by Momentum ADS software. The coupling value is �13 dB and is shown in **Figure 33**. The coupler insertion loss is 0.4 dB and is shown in **Figure 34**. The coupler S11 parameter is better than �26 dB and is shown in **Figure 35**.

**Figure 32.**

**Figure 29.**

**Figure 30.**

**Figure 31.** *Coupled lines.*

**44**

*SFG detailed measured S12 results.*

*SFB measured S11 results.*

*Innovations in Ultra-WideBand Technologies*

*18 GHz to 40 GHz, wideband MM-wave coupler.*

**Figure 33.** *The wideband coupler coupling value, S12.*

**Figure 34.** *The wideband coupler insertion loss.*

**Figure 35.** *S11 of the wideband coupler.*
