Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Help me design an array antenna

Status
Not open for further replies.

Lupin

Full Member level 6
Joined
Jan 22, 2003
Messages
342
Helped
12
Reputation
24
Reaction score
9
Trophy points
1,298
Location
Italy
Activity points
3,235
Array Antenna Question

Dear sirs,

I´ve a problem to solve:

Design of an Array Antenna whose requirements are:

- Freqeuncy range: 6-18 GHz;

- Matching < -10 dB;

- Gain > 4 dBi;

- Scanning Angle : from -45 to +45 degrees...

Seems quite hard.. doesn´t it?

Any idea is welcome.

Thanks in advance

Lupin
 

Re: Array Antenna Question

I think you should start by focussing on the design of a single antenna element. Designing an antenna with that bandwidth and RL<10dB is REALLY HARD. But if you succeed, another thing is phase shifting the feed signal. Once again this is really hard with this bandwidth, and the phaseshift will be different for different in-band frequencies.

Good luck, you'll need it.
 

Re: Array Antenna Question

Hi Radiohead,
I think that:

- Since now I have to consider ALL the array configuration, not only the single element, I can consider many single element working at diffrent frequencies instead of a single element covering all the bandwidth...
Do u have a book about wideband arrays or wideband single elements?

- i don´t see the problem in the phase shift because what is important is the phase difference between elements, not the absolute one..

Do u have design ideas ?

Lupin
 

Re: Array Antenna Question

Hi Lupin,

for a so wide bandwidth, you need true delay lines (not constant phase-delay shifters that can be used in the narrowband case).
Has the steering angle to be adjusted in many steps?
Regards

Z
 

Re: Array Antenna Question

Hi Zorro,

can u give me more informations about True Delay Lines? I was concentrating on array accomodation and single element design.

Steering angle adjustmnent.. let´s say a step of 5 degrees..

If you have papers on this argument, please upload them.

Thanks a lot for your support.

Lupin
 
Re: Array Antenna Question

Hi Lupin,

are you working on Electronic Warfare?

Vivaldi antenna elements are the most common in this field and in these bands.
 

Re: Array Antenna Question

Hi satellite,

No, I´m not working on Electronic Warfare? What do u mean?

I have to design an antenna different from Vivaldi´s... Can u help me?

Thanks in advance.

Lupin
 

Re: Array Antenna Question

- Since now I have to consider ALL the array configuration, not only the single element, I can consider many single element working at diffrent frequencies instead of a single element covering all the bandwidth...
Do u have a book about wideband arrays or wideband single elements?


Can you state this a little clearer? Do you want to transmit/receive a wideband signal? Or different smallband signals throughout the band?

- i don´t see the problem in the phase shift because what is important is the phase difference between elements, not the absolute one..

Yes but you have to make a phaseshifter that works at all frequencies with reproducable phase shift. And that is for a smallband signal. For a wideband signal you will also need flat group delay for the whole bandwidth. And that's even more difficult!
 

Re: Array Antenna Question

Lupin said:
Hi Zorro,
can u give me more informations about True Delay Lines?

Lupin,

A true delay line (TDL) is simply a nondispersive (constant velocity vs. frequency) line. Its phase delay varies linearly with frequency. This is needed in order to avoid that the steering varies with frequency.
You get angle sttering by switching TDL’s for each element in the array.
I think that the first sentence in my previous post was not clear (sorry for my English): I meant that constant phase-delay shifters (phasers) can be used in the narrowband case, but are not suitable for wideband phased arrays.
Look to Hansen’s book (Phased Array Antennas), available in this board.
Mailloux’s book (Phased Array Antenna Handbook) is also OK.

Z
 

Re: Array Antenna Question

For Zorro: OK, no problem for your English, also mine is bad but.. where can I find the Mailloux book?

For Radiohead: I checked, I need a single Transmitter/Receiver broadband element... do u have some idea or some book dealing with it? I don´t want to use a Vivaldi antenna.

I also fully agree with u for the phase shifters.

Best regards
Lupin
 

Re: Array Antenna Question

Can you give an idea what technology frame you're in?
 

    Lupin

    Points: 2
    Helpful Answer Positive Rating
Array Antenna Question

Lupin,

is it a requirement that the antenna is a phased array? or can it be a single antenna?. Have you thought on frequency independent antennas (spiral and equiangular spirals)?.

If I remember well they are quite wide-bandwidth.
 

Re: Array Antenna Question

For radiohead:
I´m designing this type of antenna as an"exercise", as you can know me from my posts in this site, you should know I´m involved in (slotted) patch antennas and phased arrays. I also developed a code in MatLab for analisys (I´m working on the synthesis) of planar arrays.. As u know, Patch antennas have a narrow bandwidth..I want to start to design broadband antennas (phased arrays exactly) to check my code and as new challenge. Of course every comment from this site is more than welcome.

For Dowjones: u are right, spiral antennas are wideband, the point is that I need a phased array to squint the Beam, as I was mentioning to radiohead, the problem is the wide frequency bandwidth.. it´s very challenging isn´t it?

Best regards
Lupin
 

Re: Array Antenna Question

HI lupin,

U will commonly find these kind of designs in the Balanis Antenna Text Book, The Linear array antenna chapter. There r so many differnt ways to design ur antenna. U can use a uniformally spaced array with uniform or a nonuniform current distribution (better). Balanis mainly talks about the Binomial and Tschebycheff arrays. U can use one of these. All the required eqns are in this chapter. But the point is that I assumed that u a linear array not a planar one. If u want to design a planar array, u will have to through nasty math. But it is not that difficult.

Armanio
 

Re: Array Antenna Question

the wideband ,you should use the ridge horn as the basic element
 

Re: Array Antenna Question

If you convert a 4dB gain into its equivalent beamwidth, I don't see the need for steering the beam in 5 degree increments. Better up the gain.
 

Re: Array Antenna Question

Hi Armanio, where can I find the Balanis Antenna Text Book? I don´t remember if I have it...

Hi edf, it´s impossible to increment the Gain .. anyway the beamdith of 4 dB is 80 degrees is n´t it? Probably the scanning step can change.

HI springf2000, do u have material about ridge horn?

At the moment i ´m focussed on the study of the planar array to avoid grating lobes in cases of squint for the entire bandwidth (it´s not easy).

There are many many subjects to consider....

Best regards

Lupin
 

Re: Array Antenna Question

Hello everybody !

What seems very strange for me is how can be realised a such array from 6 to 18 GHz with the same array structure for several reasons. Anyway before discussing these reasons some points have to be clarified:

1- the whole frequency band has to be covered, or only sub-bands ?
2- the antenna is Tx or Rx or both ?
3- which is the polarization ?
4- what is the size limit ? (diameter an height)
5- what shape of beam has to realised ? (only pencil beam or shaped beam)
6- Diffrent element can work at some frequency and other elements at other frequency ? separete feeding network are allowed for diffrent frequency band ?
7- the scan angle can vary only in one plane or all over the semishpere ?
8- please clarify the sentence: (Lupin) " I want to start to design broadband antennas (phased arrays exactly)"

The first doubt is regarding the inter-elements spacing: considering that there is available an element covering all the frequency band, its displacement in the array lattice will be strongly frequency depenedent causing probaibly grating lobes phenomena still at the boresight scan ! vice-versa if you have different elements for different frequency you probably will have difficulties to allocate the elements in the appropriate position due their phyisical size.

bye bye.
 

Re: Array Antenna Question

Hello juppydu,

I agree with many point u have shown:

1- I can try to deisgn two types of antennas: one broadband (6-18 GHz), one covering sub- bands (in this case I have to use different inputs,one for every sub-band: the sum of the sub-bands must be 6-18 GHz);

2- Antenna is Tx and RX;

3- I would like a CP;

4- At the moment there´s no size limit;

5- Do u mean masks? No, the one important thing is the Pointing and the Gain;

6- As in the point 1, it´s interesting to investigate one input antenna and multi-port antenna; in that case u can use different frequency band;

7- Broadband array antennas are challenging exactly for what you have been explaining later .. That´s my reality!

Thanks for your cooperation
Lupin
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top