Antenna 120 Deg

[RXTX]

Hi,

I need to design Antenna with a -3dB beamwidth of around 120 deg,Is anyone has ideas which antenna is compatible ?

The antenna need to be with High Gain as possible.

Please advice.

Doron

 

[MacGyverS2000]

Really? That's the amount of info you give us and expect a valid answer?

Dan - Owner

http://www.Hi-TecDesigns.com

 

[RXTX]

The antenna need to be above PCB on PCB.

 

[VEBill]

... -3dB beamwidth of around 120 deg... with High Gain as possible.

I agree with Dan that your question is almost perfectly ill-defined.

The way to achieve "high gain" and 120° [azimuth?] beamwidth (implying low gain) is to narrow the elevation beamwidth.

 

[AndreyG]

I can construct suspended plate configuration with narrow ground plane resulting in 120 deg. beam width and gain ~ 6 dBi.
Gain can be further increased by making an array of plates ...
Such design will be feasible on UHF...
MacGyver is right - you need to explain what you want: your operating frequency, requirements in detail, spatial constrains.

 

[RXTX]

The frequency BW need to 8%

 

[RXTX]

Hi,

I summerize the parameters:

Antenna with a -3dB beamwidth of around 120 Deg.
frequency of operation 4.5GHz
Frequency BW :350MHz
The antenna can be above PCB or on PCB.

Please advice.

 

[Higgler]

8% bandwidth, look up thick patch antenna. That'll work.

 

[RXTX]

Hi Higgler,

Can i receive beamwidth of 120 deg ? (i know that the beamwidth of patch antenna is around 90 deg maximum)

 

[Higgler]

Patch beamwidths depend on the dielectric you choose and they aren't 90 degree beamwidths as a rule (they can be 60 degree up to 180 degree or more. Patches can be curved also to widen the beamwidths if needed.

If you use high dielectric, the patch is smaller and beamwidth is wider. Er= 8, thickness 0.2 Lambda in the dielectric (about 0.15" thick) will work, that's a 0.18 Lambda wide antenna. That'll give you very wide beamwidth.

 

[RXTX]

Hi Higgler,

IF you increase the Er to 8 the BW is decrease.

I need BW of up to 7%.

Did you see patch antenna with this high BW and high Beamwidth ?

Doron

 

[Higgler]

Best Patch antenna book is Pozar's book, big yellow one.

http://www.amazon.com/Microstrip-An...0780/ref=sr_1_2?ie=UTF8&qid=1326039161&sr=8-2

Has all the details in it to make a thick patch antenna on page 77.

Here's notch antenna design info, it's just a slot in your ground plane edge and you cross a feed line on the other side of the circuit card and it's extremebly wide bandwidth. You can control the beamwidth easier based on size.

http://www.piers.org/piersonline/pdf/Vol3No7Page984to986.pdf

The radiation is different than the patch. Patch antenna radiates perpindicular to the plane of the circuit card, notch radiates in the plane of the circuit card.

 

[RXTX]

Hi Hilger,

In the article from piers.org the is no data that they reach to beamwidth of 120 degree.

The book i need to purchase.

There is a lot material how to increase the BW but less material how to increase the beamwidth.

Can you send me a meterial for antenna with beamwidth of 120 degree ?

may be: Printed dipole or pifa or ifa better ?

Doron

 

[Higgler]

Wide beamwidth equals small antenna. Narrow beamwidth equals large antenna.
PIFA and Printed Dipole and Notch are nearly related. PIFA is a notch with a very thin layer/line of metal on the top and ground plane on the bottom, similar could be said about a dipole too without a bottom groundplane. Dipole has a 73 degree beamwidth by the way, you can bend it and make it look like an arrow to widen the beamwidth. Notch is easier to design and build though due to it's very wide bandwidth (2:1) or 100% bandwidth (as opposed to 7%).

The notch slot depth sets the beamwidth.

You can change the beam from pointing backwards with 1/3 Lambda slot depth to being a narrow beam in the forward direction with the slot width large and tapering widely. Cross the probe 1/4 wavelength from the slot short circuit in the back.

Set the slot length at around 1/2 wavelength or sligthly less and your beamwidth will be very wide. With copper tape extending the slot opening off the end of the ground plane, you can shape the beamwidth to as narrow as you'd like. That's a nice feature in this antenna.

With really wide beam antennas, energy bounced off everything and your patterns get bumpy. 120 degree beamwidth antennas are much more difficult than a 20 degree or 50 degree beamwidth antenna to get a good smooth pretty antenna pattern shape (due simply to antenna energy scattering everywhere, then energy reradiates off scatterers).

 

[IRstuff]

As a general rule, beam width is proportion to lambda di vided by aperture

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[Higgler]

Yup agree, should have said electrically small, electrically large, would've been clearer.

 

[RXTX]

Hi Higler,

I have a question from different subject: Why the Antenna Handset designer not design the Antenna to Dipole which has the ability to be indifferent to human (As a GND) ?

RXTX

 

[Higgler]

I think PIFA's are much smaller. So size only.

Dipoles with thin wires are usually one frequency, narrow band. PIFA's can be many frequencies in a small size.

 

[RXTX]

Hi Higler,

About the antenna with beamwidth of 120 degree, it is look that the slot antenna feed complicated.

Do you have article for slot antenna with BW:7% and beamwidth of 120 degree ?

RXTX

 

[RXTX]

By the way - the antenna need to be with Linear polarization.