Bandwidth improvement parameters for waveguide structures

Hi all,

I wish to know how can the bandwidth of any waveguide related design, say a waveguide filter or waveguide to waveguide transition etc can be increased.

Regards..

SpaceDust said:

Hi all,

I wish to know how can the bandwidth of any waveguide related design, say a waveguide filter or waveguide to waveguide transition etc can be increased.

Regards..

Click to expand...

A "standard" waveguide (rectangular) has a defined bandwidth depending on its cross-section width.

Waveguide filters (as well as other types) consist of coupled resonators. BY design their bandwidth is fixed and can be made "wider" by another design.

Transitions between waveguides usually are wideband, the bandwidth depends on the narrower element.

So your question is not clear. What exactly you want to make wider?

waveguides come in various types. Some have inherently wider bandwidths than others. Single ridge or double ridge, finline, etc, are examples.

To get super bandwidth in waveguide components, one wants to try to avoid transmission line matching structures, and try for lumped or quasi lumped elements. Also, with the theory of small reflections, one finds that tapers, or step transformers with MANY steps, can have very large bandwidths indeed (at the expense of waveguide length).

I have an antenna and an waveguide to coax transition that i'M working with right nw. Antenna is a slotted waveguide type.. Now looking at its returns loss performances, both of them are quite narrow in bandwidth. what are the parameters that can increase the bandwidth for this slotted waveguide antenna and coax to waveguide transition..!!

SpaceDust said:

I have an antenna and an waveguide to coax transition that i'M working with right nw. Antenna is a slotted waveguide type.. Now looking at its returns loss performances, both of them are quite narrow in bandwidth. what are the parameters that can increase the bandwidth for this slotted waveguide antenna and coax to waveguide transition..!!

Click to expand...

Still not enough information. A slotted-waveguide horn antenna should be well matched over the waveguide band: for M-180 waveguide the full band covers 18 to40 GHz. The transition to a coaxial line should have he same bandwidth, but to my knowledge this type of transition is carefully tuned in manufacturing process.

If one of the two parts is mistuned, the system may behave as you wrote. I do not know what "parameters" you can vary to improve the RL. Look in the transition, some manufacturers tune it by a set of tuning screws. If you can loosen them or replace, try to tune the system for RL over full bandwidth with the antenna "looking" on an absorbing board.

Having the test instrumentation for this kind of adjustments is costly, however. Possibly the easier way is to ask the manufacturer to adjust the system for some cost.

the antenna type is planar slotted waveguide array, from return loss i considered a 10 dB bandwidth and its not sufficient for my application, so i'M looking for the exact parameters that would influence or improve the return loss bandwidth of this antenna type..

SpaceDust said:

the antenna type is planar slotted waveguide array, from return loss i considered a 10 dB bandwidth and its not sufficient for my application, so i'M looking for the exact parameters that would influence or improve the return loss bandwidth of this antenna type..

Click to expand...

I am no expert in antenna arrays but as far as I know arrays are not too wideband. Maybe yours is a specially designed one. For wideband applications I know mostly horns with continuing waveguide ridge like in M-180 waveguides .
I would suggest to check the wg-coax transition first for RL.

Thanks a Lot..!!

Regards..