wideband horn antenna

[yasine79]

hi all,

did someone know if it is possible to buy a wideband horn antenna (~ 200 MHz to 9 GHz) with Linear Polarization?

what is better: to use a very wideband antenna or to use diffrent antenna for diffrant frequency ranges. For exemple: to use three antenna (200MHz to 2 GHz, 2GHz to 5GHz, 5GHZ to 9 GHz) instead of one Wideband Antenna?

Thank you all

 

[Darktrax]

For a "horn" of any kind before it expands from it's waveguide..
The half-wavelength of 0.2GHz is near 750mm in air.
The half-wavelength of 9GHz is 16.6mm in air
These would be the controlling numbers for the longer dimension of any waveguide that connects to such a horn operated somewhat above it's cut-off frequency.

The higher frequencies would be propagating lossy higher order modes unless encouraged into smaller parts to capture TE11, TE10, TM01, and similar fundamental modes. To reduce the size, I am thinking that dielectric parts would also be a part of it.

So you are looking at a very big structure which might have several parts within getting smaller.
I think it unlikely you will find a ready-made horn product, but then.. I can always be surprised!

BUT.. I have seen advertised very wideband Log-Periodic products, which might include planar log-periodic antenna types on low-loss substrate. I could imagine a microwave planar log-periodic antenna set along with VHF-UHF periodic elements in a combined arrangement that might be an elegant and effective thing.

ALSO - I expect that companies that specialize in EMC testing, RFI investigations and the like are the more likely to have available very wideband radiators as might be used in field measurements.

 

[zorro]

There are broadband, multi-octave horn antennas, used for EMI/EMC measurements.
They are not fed by waveguides, but from a transition to a coaxial connector.
Regards

Z

 

[yasine79]

i appreciate your answer,
i think on something like this: ridged antenna


**broken link removed**

thank you

 

[Darktrax]

hi all,
what is better: to use a very wideband antenna or to use diffrent antenna for diffrant frequency ranges. For exemple: to use three antenna (200MHz to 2 GHz, 2GHz to 5GHz, 5GHZ to 9 GHz) instead of one Wideband Antenna?

The Chengdu ridge antenna as you mentioned covers 700MHz - 18GHz which implies that a bigger scaled-up version could cover 200MHz-9GHz. Very loosely, that might require an aperture of about 560mm. One thing I note is that the 2:1 VSWR specification is a little disappointing!

The ridge horn, you notice also has slots in the H-Plane walls, and is linear polarization. The ridge antenna concept can be taken further. I post here a copy of a report from the Jet Propulsion Laboratory, not so much for the article itself, which will be interesting, but for the list of references to very wide-band feeds.

Particularly, search for "The Eleven Antenna" which should give you some links to the decade wide dish feed. I also post the only pdf I have about the "Eleven" antenna, which is interesting because it (kind of) confirms my guess about log-periodic structures.

Given that we can all find examples of these very wide-band things, you may be closer to discovering a supplier and a product.

 

[zorro]

what is better: to use a very wideband antenna or to use diffrent antenna for diffrant frequency ranges. For exemple: to use three antenna (200MHz to 2 GHz, 2GHz to 5GHz, 5GHZ to 9 GHz) instead of one Wideband Antenna?

For what application?

One thing I note is that the 2:1 VSWR specification is a little disappointing!

It should be noticed that in antennas intended for measurement, matching is not as fundamental as in other applications. Of mainly importance for calibrated antennas is the knowledge of antenna factor.

Z

 

[Darktrax]

If intended for measurement, and you are transmitting to (perhaps) test the immunity of some kit to radiated interference, this choice might somewhat be driven by the signal generator and amplifier hardware capability.

If instead it is to monitor the emissions from kit using spectrum analyzer, then it can be a great convenience to be able to sweep all the spectrum in one test rather than have to connect up for a separate test.

My guess is that you might have to settle for two antennas, but there is some chance you might be able to find a single antenna to cover 200Mhz to 9GHz. Definitely, if a single device can do the job, then it is the antenna of choice for ease of working.

Forgive the observation about the VSWR match. In the work I do, we are always trying to drag out the very last fraction.

 

[yasine79]

Hi,
it is great to have all this answers.

I need the antenna for a transmission application. i will need two of such antennas connected to VNA. from the S-parameters i want to calculate the permittivity of some materials. the goal is a linear polarized antenna with a matching of (<-10 dB).

thanks again