# Need answer about BW and Axial Ratio

1. ## Re: Need answer about BW and Axial Ratio

dear all,,

i m new for antenna design and need information.

i have design circular polarization array antenna my questions are:

1. if we want bandwith an antenna shoulb be at 10db?
2. what is axial ratio and why should be at >=3 db?

thanks all

Added after 5 minutes:

dear all,,

i m new for antenna design and need information.

i have design circular polarization array antenna my questions are:

1. if we want bandwith an antenna, why shoulb be start at 10db?
2. what is axial ratio and why should be at >=3 db?

thanks all •

2. ## Re: Need answer about BW and Axial Ratio

i think you are talking about the return loss of an antenna which should be less than 10db for good performane.
10db return loss means that 90% of the power is radiated by the antenna.
now for a broadband antenna it should give this much return loss for a wide range of frequencies in order to qualify to be broadband antenna.
regarding axial ratio it is the measure of the ratio of the the two linearly polarized components of the field.
for circularly polarized antenna both components should be equal giving ratio of
1 (0db).
for good performace upto 3db is acceptable.
hope this helps.

1 members found this post helpful. •

3. ## Re: Need answer about BW and Axial Ratio

Hi heviraf,

With this i've enclosed basic antenna terms and its definition hope it'll help u. --[[ ]]--