BPF design

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
david753
Posts: 51
Joined: Fri Jan 16, 2004 1:01 am
Contact:

BPF design

Post by david753 » Tue Feb 01, 2005 3:46 am

I am going to design a BPF, the center is 26MHZ, span is 2MHZ.
After using ADS, I got the result at folling link.
http://homepage14.seed.net.tw/[email protected]/t0284754/26m.doc
But, I found the value of L2 is 9UF.
How can I make it?
which type core? and how many turns?

k7elp60
Posts: 226
Joined: Wed Dec 05, 2001 1:01 am
Location: Ivins, UT
Contact:

Re: BPF design

Post by k7elp60 » Wed Feb 02, 2005 4:52 am

I think you have a typo, it should be 9uH. or about 9 microhenry. I would go the the Mouser cataloge and buy a adjustable one that has a nominal value that you want.

User avatar
haklesup
Posts: 2948
Joined: Thu Aug 01, 2002 1:01 am
Location: San Jose CA
Contact:

Re: BPF design

Post by haklesup » Wed Feb 02, 2005 11:45 am

Just google on "inductor design" and you will get many hits. Some pages just had formulas, others had tables or calculators but......<p>It soon became apparent to me that one could design a family of inductors all with the same value but with different shapes.<p>One formula I found:
L=D^2*N/1000(18*D+40*CL)<p>L=inductance
D=average diameter of coil
N=Number of turns
CL-Coil Length<p>Looking deeper, it seems one might want to keep N to a minimum to keep the total wire length minimal to reduce the DC resistance. <p>but are there any other gudelines for optimizing D and CL other than the space you have to mount it and the ease of assembly (for example if it is easy to use a pencil as a form, that would dictate the D)<p>Are there any frequency domain consiquences to designing one way as opposed to an equivilent shape? Is L constant for all frequencies. Does shape effect this property or any others.<p>I know adding a solid core increases inductance depending on the permitivity of the metal in the core making the formula more complicated. For now I just want to understand air core coils a bit better.<p>Perhaps someone can outline the thought process that they use for designing the specifics of an inductor.

russlk
Posts: 563
Joined: Thu Dec 06, 2001 1:01 am
Location: New Hampshire
Contact:

Re: BPF design

Post by russlk » Wed Feb 02, 2005 4:57 pm

I have use this equation for solonoid coils with good success:
L (microhenries) = ((n^2)*r^2)/(9*r + 10*l)
n = number of turns
r = radius of coil (1/2 diameter)
l = length of winding<p>Keep in mind that the leads of the coil are also part of the inductance which is not included in the equation!

Post Reply

Who is online

Users browsing this forum: No registered users and 15 guests