CN103235194A

CN103235194A - Method for measuring circular polarization antenna axial ratio by utilizing linear polarization antenna

Info

Publication number: CN103235194A
Application number: CN2013101367475A
Authority: CN
Inventors: 李南京; 冯引良; 王剑飞; 李瑛�; 刘宁; 杨博; 陈卫军; 刘琦; 郭淑霞
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2013-04-19
Filing date: 2013-04-19
Publication date: 2013-08-07

Abstract

The invention relates to a method for measuring a circular polarization antenna axial ratio by utilizing a linear polarization antenna. The method is characterized in that the linear polarization antenna with a known polarization direction is selected to be an auxiliary antenna in a microwave unreflected chamber, polarization states of the linear polarization antenna are sequentially enabled to be the same with four polarization directions of x, y, u and v, the antenna directional graph measuring is carried out on a to-be-measured circular polarization antenna in four polarization states of the auxiliary antenna, radiation values of Ex (theta), Ey (theta), Eu (theta), Ev (theta) of the to-be-measured antenna are obtained, an inclination angle of the to-be-measured circular antenna is calculated, and an axial ratio AR (theta) of the to-be-measured polarization antenna is obtained. According to the method, a linear polarized horn antenna is adopted to be the auxiliary antenna, the polarization direction of the linear polarized horn antenna is easily determined, the measuring time is reduced, and the test difficulty is lowered; and the auxiliary antenna is in a static state, so that the affects from uncontrollable factors are reduced, and the obtained information of the circular polarization antenna axial ratio is enabled to be realer and more reliable.

Description

A kind of method of utilizing linear polarized antenna to measure the circular polarized antenna axial ratio

Technical field

The invention belongs to the antenna measurement field, be specifically related to a kind of method of utilizing linear polarized antenna to measure the circular polarized antenna axial ratio.

Background technology

In the circular polarized antenna test, need to measure the axial ratio of circular polarized antenna, whether reach designing requirement with the circular polarisation degree of judging circular polarized antenna.The rotational source method is to adopt simultaneously circular polarized antenna to be measured place azimuth rotating platform to be transferred to proper speed as auxiliary antenna by atwirl linear polarized antenna in same plane of polarization, so just can obtain more real axial ratio information.But owing to the rotary joint of polarization turntable can not be eliminated fully because the amplitude that the cable shake that rotation brings causes and the variation of phase place, particularly at high band, this phenomenon is particularly evident, can bring error to test.Because the standard round poliarizing antenna is difficult for making, do not adopt circular polarized antenna accurately to measure as auxiliary antenna usually simultaneously yet.

Summary of the invention

The technical matters that solves

For fear of the deficiencies in the prior art part, the present invention proposes a kind of method of utilizing linear polarized antenna to measure the circular polarized antenna axial ratio, realizes circular polarized antenna axial ratio test fast and effectively, saves the test duration, reduce difficulty of test, eliminate the measuring error of bringing in the shake of high band cable.

Technical scheme

A kind of method of utilizing linear polarized antenna to measure the circular polarized antenna axial ratio is characterized in that step is as follows:

Step 1: in microwave dark room, choose the known linear polarized antenna of polarised direction as auxiliary antenna, make polarized state and the x of linear polarized antenna successively, y, u, four polarised directions of v are identical, described x direction and y direction are mutually orthogonal, and u direction and v direction are mutually orthogonal; The angle of x direction and u direction is 45 degree;

Step 2: circular polarized antenna to be measured is carried out antenna radiation pattern measure under four polarized states of auxiliary antenna, obtain the radiation value E of circular polarized antenna to be measured _x(θ), E _y(θ), E _u(θ), E _v(θ), wherein θ is the test position angle;

Step 3: the inclination angle of calculating circular polarized antenna to be measured

Step 4: the axial ratio AR (θ) that obtains circular polarized antenna to be measured

AR (θ) = \sqrt{\frac{E_{x}^{2} (θ) \cos^{2} (τ (θ)) + \frac{1}{2} (E_{u}^{2} (θ) - E_{v}^{2} (θ)) \sin (2 τ (θ)) + E_{y}^{2} (θ) \sin^{2} (τ (θ))}{E_{x}^{2} (θ) \cos^{2} (τ (θ)) - \frac{1}{2} (E_{u}^{2} (θ) - E_{v}^{2} (θ)) \sin (2 τ (θ)) + E_{y}^{2} (θ) \sin^{2} (τ (θ))}} .

Beneficial effect

A kind of method of utilizing linear polarized antenna to measure the circular polarized antenna axial ratio that the present invention proposes adopts the linear polarization electromagnetic horn as auxiliary antenna, and its polarised direction is determined easily, has reduced Measuring Time, has reduced difficulty of test; Auxiliary antenna is in static state, has reduced the influence of uncontrollable factor, makes the circular polarized antenna axial ratio information that obtains more true and reliable.

Description of drawings

Fig. 1: polarised direction is chosen figure

Fig. 2: the main pole directional diagram of circular polarized antenna

Fig. 3: two kinds of method contrast effect figure

Embodiment

Now in conjunction with the embodiments, accompanying drawing is further described the present invention:

A polarization ellipse can represent that both quadrature decomposed with any orthogonal coordinate system.We select for use linear polarization component method quadrature to decompose polarization ellipse, and we adopt the linear polarization component of two groups of quadratures to test here.

Present embodiment as antenna to be measured, can rotate certain circular polarized antenna in plane of polarization, and the linear polarization pyramidal horn antenna that has exact scale is as auxiliary antenna, and test frequency is 8.5GHz.

Test operation:

1) in the darkroom, choose the known linear polarized antenna of polarised direction as auxiliary antenna, make polarized state and the x of linear polarized antenna successively, y, u, four polarised directions of v are identical, and described x direction and y direction are mutually orthogonal, and u direction and v direction are mutually orthogonal; The angle of x direction and u direction is 45 degree; It is consistent with the x direction to adjust the auxiliary antenna polarized state, circular polarized antenna travel direction figure is measured record data E _x(θ) (wherein, θ gets-50 °～50 °).

2) under identical test condition, circular polarized antenna is respectively y in the auxiliary antenna polarized state, u, travel direction figure during v, record data E respectively _y(θ), E _u(θ), E _v(θ).

3) by formula

Obtain the inclination angle τ (θ) of circular polarized antenna.

4) the data substitution formula that above step is obtained:

AR (θ) = \sqrt{\frac{E_{x}^{2} (θ) \cos^{2} (τ (θ)) + \frac{1}{2} (E_{u}^{2} (θ) - E_{v}^{2} (θ)) \sin (2 τ (θ)) + E_{y}^{2} (θ) \sin^{2} (τ (θ))}{E_{x}^{2} (θ) \cos^{2} (τ (θ)) - \frac{1}{2} (E_{u}^{2} (θ) - E_{v}^{2} (θ)) \sin (2 τ (θ)) + E_{y}^{2} (θ) \sin^{2} (τ (θ))}},

Calculate the axial ratio AR (θ) of circular polarized antenna to be measured.

In the design of circular polarized antenna, generally require AR≤3dB in major lobe of directional diagram width range.The main lobe width of this circular polarized antenna is-20 °～20 ° as shown in Figure 2, will contrast with the result of rotational source method test and the result of the present invention's test, and comparing result as shown in Figure 3.As can be seen from Figure 3, two kinds of measurement results of method of the present invention and rotational source method can be good at coincideing, and have proved the validity of this method.

Claims

1. method of utilizing linear polarized antenna to measure the circular polarized antenna axial ratio is characterized in that step is as follows:

AR (θ) = \sqrt{\frac{E_{x}^{2} (θ) \cos^{2} (τ (θ)) + \frac{1}{2} (E_{u}^{2} (θ) - E_{v}^{2} (θ)) \sin (2 τ (θ)) + E_{y}^{2} (θ) \sin^{2} (τ (θ))}{E_{x}^{2} (θ) \cos^{2} (τ (θ)) - \frac{1}{2} (E_{u}^{2} (θ) - E_{v}^{2} (θ)) \sin (2 τ (θ)) + E_{y}^{2} (θ) \sin^{2} (τ (θ))}} .