1

Effects of Quadratic Phase Error

2

Patterns at different range

• If the antenna isimpedance matched, how can we check the Antenna is in radiation?• Antenna operation is usually in Fraunhofer region• Near field region is suitable for NF measurement, why?

3

Far Field Range

Phase error of far field range

8R

d with

2 2

k

For maximum of 16

Rd

2 2

Quadratic phase error is

when

22 5.

Rd

2 2

4

• Quadratic phase error is at

22 5.

R D 2 2

• Quadratic phase error is at

1125.

R D 4 2

• Quadratic phase error is at

0

R infinity

Patterns due to quadratic phase error

Effect of Quadratic Phase Error1. Gain is reduced2. Wider the beamwidth3. Higher the first SLL4. Higher the first null value

5

Definition of Quiet Zone

1. The zone area (length, width, height) which antenna or target under test

2. Performance of E field on the wavefront

E field with taper and ripple in both amplitude and phase

3. For ideal plane wave

Amplitude: taper 0 db, ripple 0 db

Phase: taper 0 degree, ripple 0 degree

4. The larger the amplitude/phase error in the wavefront, the larger the error for the result of pattern measurement

6

Anechoic chambers and corresponding side-wall reflections

7

Antenna-range measuring system

8

Near- and far-field phase pattern measurements

9

Single frequency measuring system

10

Swept frequency measuring system

11

Polarization measuring system

12

Polarization amplitude and phase measurements