How to determine that a component is narrowband or wideband?

how to determine that a component is narrowband or wideband?
is it determined by a laboratory measurement ?
or any mathematical calculation for it?

give me some explanation about that for directional coupler

thanks a lot

Hi,
The component data sheets normally indicate the bandwidth. Usually narrowband components will be tuned and shall have better noise figure than the wideband components.

The DCs that I have used were Wideband for me. They work form DC to 2.5GHz.
I used Agilent components.

B R
M

Generally speaking:
narrowband stay for few% to 10 or 15%.
Wideband stay for bandwidth up to 1 octave
Then larger bandwidths are called "multioctave" or "ultra wide".

Often, the best technical performances are acheived by narrowband systems while best economic performaces are acheived by larger bandwidth.

OK thanks..

But what's 1 octave?

Added after 25 seconds:

OK thanks..

But what's 1 octave?

when frequency 1MHz is increated by 1 decade it means frequency is 10MHz

when frequency 1MHz is increased by 1 octave it means frequency is 2MHz

In RF when operating spectrum of certain operating mode is considered narrow-band then (let's make it 1GHz example) spectrum is between 750MHz to 1.25GHz wide.

and as sergio marrioti was saying is considered wide-band when spectrum is 600MHz to 4GHz wide at least.

Hi guys....

All is relative....
Sometimes a signal bw of 300 kHz or lower is considered wideband...
It all depends on your WANTED bandwidth.
I am not completely sure what the original question has for background.
In general if a signal is narrowband or broadband can be easely determined on a spectrum analyser. If you take eg a CW signal on a sspectrum anlyser, the amplitude does not vary when you change the analyser b/w. For a wideband signal the signal amplitude DOES CHANGE and may change a lot while varying the analyser b/w.
I hope this brings an alternative view to the statements in above replies.

rgds :P
from Mike

Yes, this is a relative issue. One possible way to tell a system is a wideband or a narrowband one is to look at the ratio of the bandwidth to the center frequency.

Dear Masadi,

In Digital Communications, Wideband is a bandwidth class between 64Kbps and 1.544Mbps whereas Narrowband is only up to 64Kbps. Should a communication device, a circuit or a channel of a certain network (usually wireless) exhibit a bandwidth of at least 64Kbps, it is termed Wideband. It is however not the carrier frequency to determine a device, a circuit or a channel as Wideband. Thus a Wideband entity can also range from DC to 32KHz, assuming 2bps.

In RF and Analog circuits, Gain-Bandwidth Product is a basic relationship. 1 Octave specifies an 2 times increase in bandwidth for a device or a circuit at the expense of a reduced gain. This only specifies a wider band, hence not necessary a Wideband. Therefore an entity subjected to 1 Octave change in bandwidth must first satisfy a bandwidth of at least 64Kbps to be considered Wideband.

I may add. in the mobile communication, coherence bandwith of the channel determines whether the signal is broadband or not. let say 30 KHz BW signal may be considered as a narrowband in one channel but not in other channels.

Yes, agreed.

It's the bandwidth that can usefully deliver data (in bps) rather than the allocated bandwidth, which may not be 100% utilised, that determines wide/narrowband.

To second and support your claim, Broadband is divided into N channels, each is usually a narrowband. However what actually determine Broadband is that the allocated bandwidths are quite specific such that Channel 1 and 4 carry Data, Channel 2 and 5 carry Audio and Channel 3 and 6 carry Video. Channel 1, 2 and 3 are Downlink channels and Channel 4, 5 and 6 are Uplink channels.

Hi everyone,

I still have doubt in understanding of narrowband and wideband. I agreed that it depends on how the system is defined for. Let's say that if I'm supposed to design a wideband system say 26-40GHz. So how do we ensure that the design would be correct? How do I see it by looking at the ratio of the bandwidth to the center frequency only? Are there any other way to justify this? Thanks.

Any professional definition between narrowband and wideband?