Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

How to calculate gain from radiation pattern?

Status
Not open for further replies.

cakalhunter

Junior Member level 1
Joined
Jan 10, 2006
Messages
18
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,546
how to calculate radiation pattern

Can anybody explain how i can compute gain from radiation pattern? I could not obtain a satisfactory solution for this problem.

Thanks in advance
 

plasma

Advanced Member level 2
Joined
Dec 20, 2001
Messages
536
Helped
79
Reputation
158
Reaction score
40
Trophy points
1,308
Activity points
3,854
measure radiation pattern

The gain G of antenna is a power ratio, function of directivity D and efficiency K :

G = K*(P max/Pin avg) = k*D (G is expressed in dB)

The directivity of an antenna is the maximum gain measured compared to its gain averaged in all directions. The directivity D of an antenna is given by the next relation : D = P (max)/ Pin (avg)

To compare performance of a 20 dB gain antenna over an isotropic, let's image that this antenna radiates its 20 dB gain (in fact 20 dBi) from the center of a sphere. This energy will travel through a surface 100 times smaller than the total surface of the sphere, or 41253squer° / 100 = 41squer° of beamwidth.

This calc. it's for 100% efficiency antenna

Dmax =4π/ΔΩ =4π/Δθrad1 Δθrad2 =41 253/Δθ°1 Δθ°2

Gmax =K/Δθ1 Δθ2

Practical
values of K fall in the range 25000–35000 (with the beamwidth angles in degrees.)
 

cakalhunter

Junior Member level 1
Joined
Jan 10, 2006
Messages
18
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,546
how to calculate radiation of entana

My friend, thanks for your help

but is there a way to obtain gain from radiation pattern? All i have is a radiation pattern.

regards
 

svarun

Full Member level 5
Joined
Mar 31, 2002
Messages
272
Helped
22
Reputation
44
Reaction score
15
Trophy points
1,298
Location
In the warm company of God's most exquisite creati
Activity points
2,757
how to calculate the radiation patterns

Let P(Θ,Φ) denote the far field radiation pattern with respect to power. You need to square if you have the field pattern. . Find P(Θ,Φ)max. Then find the average of P(Θ,Φ) by taking a grid of say 50 by 50 points or even finer. Find 10log(P(Θ,Φ)max/P(Θ,Φ)ave) That will give your gain.

svarun
 

snkhan

Full Member level 6
Joined
Oct 19, 2005
Messages
324
Helped
38
Reputation
74
Reaction score
20
Trophy points
1,298
Location
Gods place
Activity points
3,213
svarun said:
Let P(Θ,Φ) denote the far field radiation pattern with respect to power. You need to square if you have the field pattern. . Find P(Θ,Φ)max. Then find the average of P(Θ,Φ) by taking a grid of say 50 by 50 points or even finer. Find 10log(P(Θ,Φ)max/P(Θ,Φ)ave) That will give your gain.

svarun
Hi:
Please clarify the difference between radiation pattern and field pattern. Because we measure the field pattern (e.g. azimuth) in anheonic chamber which is power measurement.
 

dowjones

Full Member level 2
Joined
Nov 21, 2001
Messages
122
Helped
7
Reputation
14
Reaction score
1
Trophy points
1,298
Activity points
1,352
simply you can't.

from the pattern you get the directivity, which differs from the gain in the loss of the antenna. To have a measure of the gain you need a standard gain antenna and make a power measurement (which is out of your means if I understand properly), or an estimate of the loss of your antenna. Assumed this is the case, you have the loss (estimate) and the directivity (pattern), so you have the gain...

btw field pattern, radiation pattern is all the same.

rgdz
 

snkhan

Full Member level 6
Joined
Oct 19, 2005
Messages
324
Helped
38
Reputation
74
Reaction score
20
Trophy points
1,298
Location
Gods place
Activity points
3,213
Hi
The definition given by plasma makes sense.
G = K*(P max/Pin avg) = k*D (G is expressed in dB)


Actually measuring the radiation pattern using an antenna of known gain (usually horn antenna) is an estimation of loss in a specific plane. I think we can measure the gain by subtracting the gain of known receiving antenna to one obtained from above definition.
please let me know if i am wrong
 

VSMVDD

Banned
Joined
Jun 12, 2005
Messages
646
Helped
92
Reputation
184
Reaction score
34
Trophy points
1,308
Location
scotland uk
Activity points
0
yes you can do this be measuing using a soft media like a snow material

or a terain that is a simulation of snow

you need nec pro this has such terrain sims built in

dont listen to no it cant be done

ANYTHING can be done in a simulation with rf

you just need to filter out the idiots first

simply put
you need a buffer media and detract it from real life terrain
this way you can duduce gain over a given terrain region

actual gain is given over an isotropic for a perfect sim

but i think this isnt what you want

so nec pro is....
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top