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How to increase beamwidth of Vivaldi antenna

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akedar

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beamwidth of an antenna

I am designing an antipodal vivaldi antenna in c- and x-band. I want to get a beamwidth of 120 deg throughout the band. But I am not able to do so. When i achieve the beamwidth symmetry of the pattern goes


Can anybody help me asap..itssssssssssss urgent
 

raghuram_msc

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vivaldi antenna

Hi Buddy,

But what is your approach at design..?? I mean how are you trying to synthesise the Beam? May we share yur exact antenna design??

Regards,
sai
 

akedar

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vivaldi .hfss

i dont get ur question...actually i m trying to control the flare to increase HPBW but i m not able to get symmetrical and 120 deg BW.

can u elaborate ur question
 

snkhan

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beamwidth of a symmetrical pattern antenna

Easy way is to change the flare angle of the vivaldi and increase the substrate thickness.
 

akedar

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vivaldi flare

i tried flare altering that increases the BW but assymmetry is introduced..how to make pattern symmetrical abt. boresight
 

snkhan

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It usually occur at higher frequency but i think that by increasing the ground u can overcome the situation.

Can u please upload ur model if possible.
 

alkuhail

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Easy way is to change the flare angle of the vivaldi and increase the substrate thickness.
 

heedavid

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I don't know about this, but is it possible to increase (or shape) your beamwidth of the anti-podal Vivaldi by extending and shaping (maybe a semi-circle) your substrate well past the Vivaldi's aperture? Think of it as a 'radome' or 'WAIM' (I think it's called wide aperture impedance matching) sheet.

Let me know if it works!
Dave
 

akedar

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Hi snkhan

i am posting my file consisting of only rear part which i m adjusting to control beamwidth
kindly see if u can help me

thanx in advance
 

snkhan

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Hi

i am not good at HFSS but i think there is something wrong with waveguide port its too big in size and as far as i know about HFSS port dramatically chages the results. The design seems to be directional Vivaldi but i since its half part of ur desing why the pattern is steered to an angle.

But i can suggest you u to increase the width of ground (or decrease the width where vivaldi patch is connected to SMA connector i.e optimized both). In your case, both the lower and upper portion of vivaldi are exactly same that might will help stable pattern at higher frequency.

Considering the beamwidth 120° at 8 GHZ its rather difficult in the sense that directnal antennas are more directive at higher frequency Gain∞1/λ. So u need tooptimize beamwidth at higer frequency and surely will get more than 120 at lower.
 

DrunkBear

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hi akedar,
i'm also working on vivaldi lately. i'm wondering of which plane he the beamwidth you are referring to is , azimuth or elevate plane?

Added after 4 minutes:

hi everyone,

what i need is design an omnidirectional UWB Antenna, but with very sharp beamwidth on the elevation plane--no more than 30 degrees HPBW.
Is vivaldi a promising candidate?
Thank you!
 

akedar

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i am talking about azimuth plane
need 120 in azimuth and 90deg or more in elevation
 

DrunkBear

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akedar said:
i am talking about azimuth plane
need 120 in azimuth and 90deg or more in elevation
According to some literature, the beamwidth of E and H plane could be changed by applying different taper shape, e.g, if elliptical tapering shape is applied, similar beamwidth in both planes is achieved.

BTW, how the E/H plane is defined in vivaldi, and why?
Thank you!
 

snkhan

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DrunkBear said:
hi akedar,
what i need is design an omnidirectional UWB Antenna, but with very sharp beamwidth on the elevation plane--no more than 30 degrees HPBW.
Is vivaldi a promising candidate?
Thank you!
In my opinion you cannot get omni-directional azi and sharp ele together. for omni-directional you need to use coplanar waveguide to feed but at the cost of low gain. E-beamwdith 30° is directional vivaldi, i wonder how can you get both azimuth and directional properties in same design as both are converse to each other.

Hi akedar
Your design seems to be application specific because most of vivali are being used in highly directional receiving. But what are your gain requirements because HPBW will reduce the gain considerably specially at low frequencies.

Regads
 

DrunkBear

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hi snkhan,
thanks for your comments!
it seems from you that omnidirectional vivaldi antenna could be achieved by the CPW feed. So would you pls recommend me certain papers, for the strip line/microstrip line/slot line is usually used as feedline in most literature i'm studying.
In addition, i'm wondering if both azimuth omnidirectional and elevation sharp beamwidth could be simutaneously realized by using several directional vivaldi antennas, e.g 6 antennas, with one of which covers 60 degrees in the azimuth plane, then 6*60=360 degrees to cover the whole azimuth plane. Maybe again the feed line is the key of design for this.
Is it of some feasibility? What do you think? Thanks!
 

snkhan

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I think is will be little harsh as an antenna designer to do but i think you come up with good idea. If you want to use an array then u might get good pahse matching and and improvemnet at first side lobe.

Why not get dual polariztion using vivaldi

following papers might be helpful for you
 

akedar

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Hi all
I hav to design this element for phased array ..i am using this element because i need constant beamwidth and gain at all frequencies in the band.


i can afford to have 3-4dB gain as i am designing active phased array and i can make up for the gain

i dont need omni antenna..i need 120 deg in e-plane and 80-90 deg in H-plane.

also low cross-pol

can you tell me some points to do that..i hav already posted my structure in the forum

i am using mstrip feed as it suits my array requirements
 

DrunkBear

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Many thx to snkhan for ur share!
i'd like to further discuss this topic after i studying these papers.
 

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