Tool 04

Antenna Near-field Measurement

Plan near-field scan size, sampling interval, probe spacing, and measurement grid requirements for antenna measurement setups.

Parameters

Enter a reference frequency, AUT or scan size, measurement distance, and maximum measurement angle. Set the graph sweep range separately below.

Reference Frequency
AUT Width
AUT Height

Measurement Geometry

Measurement Distance z
λref

Planar mode uses measurement distance z directly for scan area sizing.

Maximum Measurement Angle
deg
Advanced Settings
Sampling Factor
×λref

The default sample spacing is λref/2.

Sweep Graph

Measurement distance z uses each frequency point's wavelength basis: 5.000λ(f).

Custom Data Step applies to Linear X scale; Log X uses automatic logarithmic points.

X Axis
Y Axis

Reference Values

λref
29.979 mm
Measurement z
149.896 mm
Rotation Radius
0.000 mm
Effective z
149.896 mm
Points
103 × 103
Available AUT
1.481 × 1.481 m
Diagram
Antenna near-field measurement geometry diagramA near-field measurement schematic showing AUT height, scan area, maximum measurement angle, and measurement distance z.AUT Height(DAUT)θmaxScan Area(Lscan)Measurement Distance z(z)

Formulas

Reference Wavelength

Calculate the wavelength from the reference frequency.

λref=cfref\lambda_{ref} = \frac{c}{f_{ref}}

Sample Spacing

Planar near-field sample spacing. The default is λref/2.

Δ=kλref\Delta = k\lambda_{ref}

Measurement Distance

Reference calculations convert distance to a λref multiple; frequency sweeps convert each point to its wavelength multiple.

z=Nλλref,z(f)=Nλλ(f)z = N_\lambda\lambda_{ref},\quad z(f)=N_\lambda\lambda(f)

Cylinder Effective Distance

Cylinder mode adds the AUT rotation radius to the measurement distance before scan area sizing.

zeff=z+Rrotz_{eff}=z+R_{rot}

Scan Area

Add the margin from effective measurement distance and target angle to the AUT size.

Lscan=DAUT+2zefftan⁡(θmax)L_{scan} = D_{AUT} + 2z_{eff}\tan(\theta_{max})

Point Count

Divide scan area by sample spacing to calculate the required point count.

N=⌈LscanΔ⌉+1N = \left\lceil \frac{L_{scan}}{\Delta} \right\rceil + 1

Max AUT Size Inversion

Maximum AUT size that can satisfy the target angle within the given scan area.

DAUT,max=Lscan−2zefftan⁡(θmax)D_{AUT,max} = L_{scan} - 2z_{eff}\tan(\theta_{max})