Author details

#### Ilkyu Kim

a good agreement with the measurements. It can be concluded that the validity of the simula-

Figure 9. (a) Evaluation using Friis formula, asymptotic Friis formula, integral form of coupling formula, and FEKO

An error of the proposed numerical methods is evaluated with respect to the full-wave simulation. The mutual coupling between identical Ku-band horn antennas is computed using the two methods: (1) Friis formula with gain reduction factor and (2) Integral form of coupling formula. The graphs of the proposed methods and measurement are shown in Figure 9. It is worthy noting that the proposed two methods are all effective within Fresnel region while the integral coupling formula extends its effectiveness to the radiating near-field region. The mutual coupling of the asymptotic Friis formula and integral form of coupling formula deviates from the simulated one at the distance of less than R = 3λ and R = 2.3λ, respectively. Beyond the each nearest separation distance, it is observed that maximum error with respect to the simulated result is less than 0.5 dB, which corresponds to around 11% deviation in power level. It verifies that the two numerical methods can provide the reasonable agreement with

The mutual coupling between one antennas placed in radiating near-field and far-field ranges of the other antenna is calculated using proposed formulas and evaluated through full-wave simulation and measurement. It is shown that those formulas enable to provide enhancement in the radiating near-field region in comparison to the standard Friis formula. The optimal formula can be selected depending on the availability of input information, the proximity of range, and the flexibility of antenna geometry. The important features of those two formulas are summarized in Table 2. The validity of simulated mutual coupling level is evaluated through the measurement. The setup of indoor measurement is discussed, and the key factors to affect the accuracy of the

tion is successfully evaluated with the measurement.

68 Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing

7.2. Error analysis of the two numerical methods

simulation and (b) close up in the radiating near-field region.

respect to the full-wave simulation.

8. Conclusion

Address all correspondence to: ilkyukim@gmail.com

Defense Agency for Technology and Quality, South Korea
