Antenna Efficiency

barkleyfans

For general PIFA antenna efficiency：
GSM about 40%
DCS about 60%

(1)how to caculate? did it has formula?
(2)why higher band efficiency is batter than lower band?
(3)how much the efficiency of monopole and PIFA?
(4)thx. for your answer.
[em01]

Dracon

(1)一般来讲用微带天线理论是可以计算的, 但是从手机天线设计角度考虑, 这种纯理论的计算来设计天线意义不大
(2)受手机PCB扳长度的影响, 一般低频段的带宽不如高频段的宽
(3)一般来讲PIFA的效率比Monopole的要小一些, 但也因环境和空间的大小而定.

barkleyfans

thx. Dracon......for (1), I mean how to caculate efficiency? such as η=D/G, how can I transfer three cut EIRP to efficiency? any formula can be used? [em13]

Dracon

confused! you mean you wan'na caculate the antenna efficiency by youself? how about the Gain? how to get the Gain?
two ways:
using software
test antenna in chamber get the gain and caculate the 3D efficiency by software .

longas12

Good!barkleyfans isn't chinese that we will not tell  this  with that nonman

barkleyfans

First, Longas12 u have a wrong gress...I'm Chinese.
Second,
Dear Dracon:thx for your answer, I mean if I could get the gain in chambe how can I know or caculate the efficiency by math operation? efficiency should and can be caculated by formula coz we could get the gain by measuring TRP, by the way, the efficiency which how can be computed? everybody know it? [em13]

rachel

In my opinion, efficiency is defined as: eff=radiated power/input power.
In active test,once you get the TRP, efficiency could be calculated as: eff(dB)=TRP(dBm)-conducted power(dBm).

barkleyfans

thx. for Rachel's answer.
I think that it may be wrieted from  eff(dB)=TRP(dBm)-conducted power(dBm) into eff(dBm)={[conducted power(dBm)-|TRP(dBm)-conducted power(dBm)|]/conducted power(dBm)}*100%. it's my surmise. [em07]

rachel

for example, conducted power=33dBm,TRP=30dBm, so eff=30-33=-3dB=50%

barkleyfans

ic, thank you very much, Rachel. [em08]

wave

PIFA 天线 GSM 可以做到55% 以上, 下面可以有speaker, DCS也可以做到50%以上. 天线面积吗也不一定很大,好坏在方案和技巧.

Zerolu

如果只知道天线的Peak gain 2dB, efficiency -2.87dB
能算出efficiency是%多少吗？