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It can't be done. Try another solution.I hope to design an air-core transformer which may operate at 100-500 MHz.
However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
Like a transmission-line transformer, which can even be madejmgong74@tom.com wroth:
I hope to design an air-core transformer which may operate at
100-500 MHz. However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
It can't be done. Try another solution.
It can't be done. Try another solution.I hope to design an air-core transformer which may operate at 100-500 MHz.
However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
Experience. (With trying to create such a design that's viable,James Meyer posted:
Jim wroth:
I hope to design an air-core transformer which may operate at
100-500 MHz. However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
It can't be done. Try another solution.
I don't have time to get deep into this, but I don't see why it
can't be done. Probably a couple turns tuned on one side.
Why do you dismiss it as impossible?
RF inductors are often wound without cores, especially at VHF and UHF.On 22 Nov 2004 15:08:36 -0800, jmgong74@tom.com (Jim) wroth:
I hope to design an air-core transformer which may operate at 100-500 MHz.
However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
It can't be done. Try another solution.
What is your loss like WITH a core? Maybe the core is not yourI hope to design an air-core transformer which may operate at 100-500 MHz.
However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
Right. But the output of a transformer (two coupled inductors)RF inductors are often wound without cores, especially at VHF
and UHF.
Low loss wideband RF transformers are almost never wound without cores."James Meyer" <jmeyer@nowhere.net> wrote in message
news:m715q01a0abrihaqas7ljcdvlvuki2uj6o@4ax.com...
On 22 Nov 2004 15:08:36 -0800, jmgong74@tom.com (Jim) wroth:
I hope to design an air-core transformer which may operate at 100-500 MHz.
However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
It can't be done. Try another solution.
RF inductors are often wound without cores, especially at VHF and UHF.
Leon
But that's with cores. If there's no core, and the length is madeExactly. A common practice is to wind the windings by twisting them
together, bifilar or trifilar, etc. This increases the coupling. At
several hundreds of MHz, the turns may be just a few or one turn.
Here's a tutorial on how to wind one.
http://www.electronics-tutorials.com/amplifiers/broad-band-amplifiers.htm
Watson A.Name - \"Watt Sun, the Dark Remover\" wrote...
Exactly. A common practice is to wind the windings by twisting them
together, bifilar or trifilar, etc. This increases the coupling. At
several hundreds of MHz, the turns may be just a few or one turn.
Here's a tutorial on how to wind one.
http://www.electronics-tutorials.com/amplifiers/broad-band-amplifiers.htm
But that's with cores. If there's no core, and the length is made
long enough for the desired response, you'll end up primarily with
a coupling capacitor. Or a transmission line.
--
Thanks,
- Win
It isn't clear (to me, anyway) why you are specifically seeking an air-coredlegg <legg@nospam.magma.ca> wrote in message news:<n076q0l32ektjtrb9fq93mkvkk2ish00oc@4ax.com>...
On 22 Nov 2004 15:08:36 -0800, jmgong74@tom.com (Jim) wrote:
I hope to design an air-core transformer which may operate at 100-500 MHz.
However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
What is your loss like WITH a core? Maybe the core is not your
problem. What application/environment?
Google 'air-core transformer', 'air cored transformer', 'coreless
transformer', 'contact-free transmission', 'contactless transmission',
'transcutaneous energy' etc.
RL
I observed two unwanted phenomenon:
1. direct capacitive coupling between primary/secondary coils. It
interferes with the mutual inductance, and makes the transmissivity of
the transformer change significantly with frequency.
2. Insertion loss is higher than 10dB.
I googled air core transformer before i posted my question. It is
weird that the concept is mentioned in many places, but I can never
find a real one which works in VHF/UFH band except transmission-line
type.
My purpose is for impediance matching, from 50 ohm cable to a 0.5 ohm
load.
To my understanding, air-core transmission-line transformers have
fixed conversion ratio, e.g. 1:1, 4:1 or 1:4, is it right? What i need
is a ratio of 10:1.
I saw some companies provide RF transformer with ferrite coil inside.
The insertion loss is only 1-2dB, however, for UHF band, the maximum
ratio is 4:1 or 6:1 only.
Looks to me like you need more lie a hundred to one.My purpose is for impediance matching, from 50 ohm cable to a 0.5 ohm
load.
To my understanding, air-core transmission-line transformers have
fixed conversion ratio, e.g. 1:1, 4:1 or 1:4, is it right? What i
need
is a ratio of 10:1.
You can do 9:1 or 16:1 with bifilar wound air core coils.I saw some companies provide RF transformer with ferrite coil inside.
The insertion loss is only 1-2dB, however, for UHF band, the maximum
ratio is 4:1 or 6:1 only.
It isn't clear (to me, anyway) why you are specifically seeking an
air-cored
solution. What is the problem with a ferrite core? You can get a
very good
match with a 3:1 turns ratio, or if you really want to get precise
then increase
the turns so you get M:N ratio closer to SQRT(10).
Because that's what the assignment was.On 23 Nov 2004 09:53:58 -0800, jmgong74@tom.com (Jim) wrote:
legg <legg@nospam.magma.ca> wrote in message news:<n076q0l32ektjtrb9fq93mkvkk2ish00oc@4ax.com>...
On 22 Nov 2004 15:08:36 -0800, jmgong74@tom.com (Jim) wrote:
I hope to design an air-core transformer which may operate at 100-500 MHz.
However I found the loss is too high.
Can anybody give me some advices to design air-core transformer?
Thanks a million!
....
It isn't clear (to me, anyway) why you are specifically seeking an air-cored
solution. ...
The "best method," of course, is the one that yields the most nearly idealIf I　simply need a narrow-band transformer, e.g. 300MHz with
bandwidth>1MHz, what is the best method? I don't need continuous
tuning, so I can make a set of such transformers to cover the range of
100-500MHz.
Awww ferk - misread that bit didn't I ....budgie wrote:
On 23 Nov 2004 09:53:58 -0800, jmgong74@tom.com (Jim) wrote:
(snip)
My purpose is for impediance matching, from 50 ohm cable to a 0.5 ohm
load.
It isn't clear (to me, anyway) why you are specifically seeking an air-cored
solution. What is the problem with a ferrite core? You can get a very good
match with a 3:1 turns ratio, or if you really want to get precise then increase
the turns so you get M:N ratio closer to SQRT(10).
I agree about the ferrite, but he needs a 100:1 impedance change so a
10:1 turns ratio.
Ah, that's easy. You want a tuned impedance matching network,If I simply need a narrow-band transformer, e.g. 300MHz with
bandwidth>1MHz, what is the best method? I don't need continuous
tuning, so I can make a set of such transformers to cover the
range of 100-500MHz.
Could you please tell me what is the upper frequency limit of ferriteIt isn't clear (to me, anyway) why you are specifically seeking an air-cored
solution. What is the problem with a ferrite core? You can get a very good
match with a 3:1 turns ratio, or if you really want to get precise then increase
the turns so you get M:N ratio closer to SQRT(10).
I switch to ferrite core now.
The guy who made the core will tell you.budgie <me@privacy.net> wrote in message
It isn't clear (to me, anyway) why you are specifically seeking an air-cored
solution. What is the problem with a ferrite core? You can get a very good
match with a 3:1 turns ratio, or if you really want to get precise then increase
the turns so you get M:N ratio closer to SQRT(10).
I switch to ferrite core now.
Could you please tell me what is the upper frequency limit of ferrite
core? I heard from someone that the limit is 200MHz.