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Anymore about Coupling: Try to read "Relevence of coupling effects on DRA array design" on I.E.E.E. Transactions on Antennas and Propagation of February 2003....There is an introduction to mutual couplings, a nice way to keep them in account (unfortunately useful for DRA only) and an useful technique for simulation's overhead reduction
hi egliu,
I'm afraid that I dont fully agree with you. If you have a low sidelobe array for e.g. 40dB SLL you should consider all coupling terms which are higher to that value (if copling to the third element is higher than 40db you should also consider it). In any case I again insist on the excitation errors issue. In order to have a tight control of SLL the most important factor is the excitation error. pls. check the radar handbook. there is also a pretty nice paper by pozar and kaufman (APS Aug 90) which analyzes several topics on errors in low sidelobe microstrip antennas and it concludes the excitations and the elements positions as the most significant responsibles for errors in SLL. Obviously the sensitivity is linked to the number of elements in the array (the higher the number the lower the sensitivity, so a large array allows larger errors).
on the other hand, it is also obvious that if the couplings can be taken into account the synthesis will be much better, and in fact scan blindness occurs by the effect of the element couplings, so that if jamez wants to take this effect into account, he must include couplings in the simulations (bad luck!!).
Try to act on the element factor, not only in the array factor. In this case you can acheive this SLL by dividing it into two factors: the first one due to the element factor and the second one due to the array.
By the way you've another degree of freedom that is the use of reflectors (not necessary parabolics).
bye
Hi mrm,
are u involved in Phased array study? I have myu own code and I would like to compare the goodness of the results, the simulation time with someone. Can we work together?
Hi Lupin
I was graduated studing antennas.
I'll be glad to talk with you about our interest...please tell me more about your simulations. Now I'm not working on antennas and I haven't much simulators...but I still remember something and even if this could be useless for you it will be funny.
By
Mrm
Hi Claudio
I suggest to study a published configuration, so we can compare our results with the officials. I told something about coupling and I cited a IEEE AP Paper (march 2003). I think this could be nice to study, but you can have some problems with dielectric materials. If U have better configurations (published), please reply to me.
Ciao Marco
What type of antennas did u study? I'm focused on planar integrated antennas and array. I've finished to write a self-made code about planar arrays (analysis and optimization). I've done it in my spare time and I'ld like to make a lot of checks on "not-standard" array configurations.
If you agree, we can establish a configuration and exchange RF results (if u have a code or some other tool).. What do u think? Hope u r a seious Elektroda navigator.
My code is derived from an fdtd, so it doesn't works so wull with thin antennas. I have some other code for planar array set up (derived from MOM with basic function optimised for planar antennas) and I used them expecially for patches. Unfortunatelly this kind of code understimate slot feeder (I build some antennas and I found this), but this is only a little neglet in coupling coefficient. Since results are usually presented in dB this is not a problem. Tell me what do you think... I recommend to start with little arrays (linear or planar) and develop Bloch functions for larger arrays. By the way I apologize, but next week I'll be abroad and I will not be able to join this group..
Bye Mrm
I think to proceed in this way:
- 2 x 1 array, 0.7 lambda spaced (frequency for example 1.5 GHz), uniform AM and PH excitation, point-source:
computation of Array Factor on fi=0° and fi =90° plane. Determination of null positions, Beamwidth (-3dB), Side Lobe Level (in dB).
- same configuration but different AM excitation (e.g. -15 dB, 0dB):
computation of the same parameters.
- same configuration but different PH excitation (e.g. -45°, -90°):
computation of the same parameters and also Boresight direction.
This is just the beginning. what do you think?
Does your code compute Directivity? I've to check it very closely because the results are wrong at the moment.
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