Any one knows how I can get design parameters of pyramidal horn antenna?I want to design antenna operating in range of 3.1-10.6GHZ(Medical range) with mid frequency of 7GHZ.I have a =.9 in ,b=1.78 inch.My question is how to find aperture dimensions a1 and b1?
Find a horn antenna in the literature or a text book and then scale it. For example, if you find a horn antenna that works from 10 GHz to 40 GHz, you would scale all physical dimensions by the constant s. The constant s is calculated from the ratio of the center frequencies.
fc1 = (3.1 + 10.6)/2 = 6.85 GHz
fc2 = (10 + 40)/2 = 25 GHz
s = fc2/fc1 = 3.65
Now you have a design that covers from 2.74 GHz to 10.96 GHz.
It is complex design, because your frequency range cover more than two standard bands. So, to feed the proposed horn, you have to use a standard waveguide!!!
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Waveguide
Designation a (in) b (in) t (in) fc10 (GHz) freq range (GHz)
WR187 1.872 .872 .064 3.16 3.95 – 5.85
WR137 1.372 .622 .064 4.29 5.85 – 8.20
WR90
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I don't know how Dr. Raymond Rumpf (response 1) made this calculation ?
[Now you have a design that covers from 2.74 GHz to 10.96 GHz.]
The above approach discussed is reasonable; however, if you need to provide a more rigorous analysis, the textbook Antenna Theory by Constantin Balanis has a fairly comprehensive section on the theoretical aspects of the design of a pyramidal horn.
As also mentioned above, the feed design could be challenging. You may need to consider a coax to WG transition. There is a reasonable discussion of this in the text book "Microwave Transition Design" by Jamal and Shahin Izadian. Their approach is a little more practical, and a little less theoretically rigorous.
http://www.amazon.com/Antenna-Theory-Analysis-Design-3rd/dp/047166782X/ref=sr_1_2?s=books&ie=UTF8&qid=1449159395&sr=1-2&keywords=antenna+design
Thank you guys for your thoughtful comments,@carlos thanks for suggesting those textbooks .I agree Constantin's book is great resource and i am going to check out Jamal's book as well.Hamza your approach is very valuable,it looks like that is what most people have used so far,I just wanted to take another approach.Dear Dr Raymond I am looking into your suggested method as well but if you might have any written document that I can go over that will be helpful!!Again i appreciate everyone's input!
You should take care about your desired application. If you generate superior modes in a waveguide, your radiation pattern will change, so you can interfere some other systems working in this interval. Maybe you can consider a vivaldi feed in order to give broadband characteristics to your antenna. You can use a Ridged horn antenna.
I would advise you to use the excellent matlab code available from Prof. Orfanidis, http://www.ece.rutgers.edu/~orfanidi/ewa/ . The one you need is hopt.m - for input you need the feed dimensions and gain.
It works very well, later you can simulate it on CST, for instance, the results from hopt and CST agree very well.
If you have "Ansoft HFSS antennas Design kit", then you will find dimensions of most of the standard antennas like horn, patch, vivaldi, spiral, log periodic..
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