### I. Introduction

### II. Compact-Standard Antenna Method

*d*) and height (

*h*) between the STA and the AUC. Then, the AF of the AUC can be calculated with the SIL measurement between two antennas, where the STA is an antenna whose AF is already known. The pyramidal horn antenna is used for antenna calibration above 1 GHz.

*E*

*) is given at the receiving location, then the distance*

_{R}*d*

_{1}between the transmitting antenna and the receiving antenna is as follows:

*G*

*is the gain of the transmitting antenna, and*

_{T}*P*

*is the output power of the transmitting antenna.*

_{T}*AF*is the parameter that determines the unique performance of the antenna.

*AF*is defined as the ratio of the field strength (

*E*) to the voltage (

*V*) induced at the receiving antenna as follows:

*T*

*)*

_{X}*AF*is

*AF*

*, and the receiving antenna (*

_{TX}*R*

*)*

_{X}*AF*is

*AF*

*,*

_{RX}*AF*can be calculated as follows:

*SIL*is a site insertion loss between the two antennas,

*f*

*is the frequency in MHz, and*

_{MHz}*d*is the separation distance in meters.

*STA*that knows the values either

*AF*

*or*

_{RX}*AF*

*is used in Eq. (3), then the*

_{TX}*AF*of the

*AUC*can be calculated as only one measurement with the following equation:

*AF*

*is the AF of the STA,*

_{STA}*AF*

*is the AF of the AUC,*

_{AUC}*SIL*

*is the site insertion loss of the STA, and*

_{STA}*SIL*

*is the site insertion loss of the AUC. Now,*

_{AUC}*AF*

*and*

_{AUC}*AF*

*must be calculated at the same position (the antenna height (*

_{STA}*h*) and the separation distance (

*d*) from

*R*

*antenna). In other words, if there is an STA whose AF is known, then the C-SAM can easily calculate the AF of the AUC with only one measurement.*

_{X}### III. Test-Site Evaluation of the FAR Condition

*T*

*and*

_{X}*R*

*) are placed at a height of 2 m from the ground plane. The antennas used for the measurement are the Schwarzbeck BBHA 9120 D model. The direction of the two antennas is vertical polarization, and an absorber is placed on the ground plane. The measurement method calculates the SIL between the antennas by moving the distance of the*

_{X}*T*

*antenna from the fixed*

_{X}*R*

*antenna to 2.8 m, 2.9 m, 3.0 m, 3.1 m, and 3.2 m. The measurement frequency range is 1–18 GHz (500 MHz steps).*

_{X}*S*

*is the transmission cable loss ratio, and*

_{21cable}*S*

*is the transmission loss ratio of the antennas.*

_{21antennas}*A*

*(*

_{im}*d*) for each varied distance by the movement

*T*

*antenna is normalized for 3 m, which is the central position of the*

_{X}*T*

*antenna, can be defined as the following equation:*

_{X}*A*

*(*

_{im}*d*)

*for each distance are within ±0.5 dB (peak to peak*

_{Normalized 3m}*A*

*(*

_{im}*d*) ≤ ±0.5 dB), the test site is said to satisfy the FAR condition [12].

*A*

*(*

_{im}*d*) ≤ ±0.5 dB), in the range of 1–18 GHz (Fig. 3). Therefore, the antenna calibration test site may be defined as free-space conditions for the frequency range 1–18 GHz.

### IV. Experimental Validation

*d*= 3 m), the antenna height (

*h*= 2 m), and the absorbers are installed on the ground plane.

### V. Conclusion

*A*

*(*

_{im}*d*)

*for each distance were within ±0.5 dB, and the test site was validated as the free-space condition. The C-SAM was compared with conventional antenna calibration methods at the test site satisfying the FAR condition, and the proposed method was verified by confirming that the maximum deviation for 1–18 GHz was ±0.18 dB. Contrary to conventional antenna calibration schemes, and if one AF is known on the calibration test site that satisfies the free-space condition, the number of SIL measurements can be reduced using the C-SAM. In addition, this method can be a suitable candidate for the revision of the measure CISPR 16-1-6 and a reduction in the measurement cost.*

_{Normalized 3m}