hello,everyone, I simulated a quarter wavelength monopole vertically placed on a infinit ground plane using CST MWS,opting the discrete port,template was antenna(with ground plane) ,other parameters such as mesh properties as same as the dipole that is given in CST examples,but I were surprised to find the directivity of monopole was 5.3dB on the phi plane,I don't kown where the fault is ,,Can you tell me how to simulate the monopole ? hope your reply!Thanks!
Hi Beiga I think you have a correct simulation but you are looking at the absolute directivity in the 3D plot instead of directivity in phi plane. Try 2D plot then it become clearer to you. In mine, Directivity phi about -70dB at theta=80. Element7k
Hi,Element7K, In 2D plot ,directivity is still 5.3dBi.....,moreover,I think the directivity pattern both opt the absolute value whether in the 3D plot or in the 2D plot,what do you think about? sincerely beiga
Hi,Element7K, In 2D plot ,directivity is still 5.3dBi.....,moreover,I think the directivity pattern both opt the absolute value whether in the 3D plot or in the 2D plot,what do you think about? sincerely beiga Beiga, please post here your project (packed, without results - it will have few kB). We will check it and guide :) Regards, Eirp
Hi Beiga, I have attached a very simple simulation with infinite gnd in C/S/T. I think you got confuse about cut planes and I think the reason might be that you have used @/n/s/o/f/t before using C/S/T. Anyway, I will like to recap that an ideal monopole has directivity x2 of a dipole antenna. In the ideal case, directivity = gain. So Monopole in the Z-axis with directivity 5.3 dB is okay in the veritical plane. (Labelled Theta in C/S/T) To make the picture clearer, you can change the 3D view to polar plot. Sorry my mistake for saying its 2D previously. Change the polar plot to plot --> vary phi, Theta=85 (I chose 85 because at 90 degrees for infinite gnd plane you have nothing) Now, if you click on phi in the navigation tree, you should get a reading of -64.2dbi. This is the horizontal component so as expected it is small. (Veritical dipole cannot have horizontal component). If you click on Theta (Vertical componet) you have 5.3dBi which is about x2 that of a dipole. :) There you got it! 8O Correct me if I'm wrong. Hope this helps. Cheers, Element7k
Hi,Element7k, At first,I must thank you for your help! But I must correct you that an ideal monopole on infinte ground plane has directivity equal to its corresponding dipole antenna!so。。。。。 :( sincerely beiga
Hi,Element7K, In 2D plot ,directivity is still 5.3dBi.....,moreover,I think the directivity pattern both opt the absolute value whether in the 3D plot or in the 2D plot,what do you think about? sincerely beiga Beiga, please post here your project (packed, without results - it will have few kB). We will check it and guide :) Regards, Eirp Hello,Erip, sorry,I don't know how to pack the monopole model on the forum,but I can send it to your e-mail,would you like to tell me your e-mail,or you tell me how to pack the model! Hope your help!Thanks! sincerely, beiga
Beiga, ideal monopole (infite ground plane) has directivity +3dB compared to its corresponding dipole, coz the power is radiated into half space under ground plane! If you consider dipole with D=2.15 dBi then monopole D~5.3dBi is correct value To add your project here: MWS: a) Delete results b) Pack all the directory with your project using ZIP/RAR Elektroda: Click reply and under the text box there's Options-Add an Attachment... Your project will be available to download here :) Rgz, Eirp
Hi,Erip, Where does the conclusion(ideal monopole (infite ground plane) has directivity +3dB compared to its corresponding dipole, coz the power is radiated into half space under ground plane!)come from? 'monopole directivity on infinte ground plane equal the dipole directivity'',the conclusion you can find in the book'Modern Antenna design' you want is in the attachment! sincerely, beiga
Ooops, You uploaded only .bmp! You must compress all the directory with your project (contains many files like .sat,.lok,.afi,.clp,.crd...). I must be available run it in my MWS from your attachment. Please retry. Ground plane creates image under the up arm so instead lambda/2 only lambda/4 is required. If the ground plane is infinite, waves can't pass under and total power is transmitted to half space only thus directivity +3dB. Eirp
Hi Beiga&Eirp, Here is a slide supporting eirp's theory and the concept that the ideal monopole has x2 directivity (i.e. +3dB) of dipole. :) I think picture explains a thousand words. I get confused reading too much! 8O Hope it helps. Element7k beiga[/quote]Hi,Element7k, At first,I must thank you for your help! But I must correct you that an ideal monopole on infinte ground plane has directivity equal to its corresponding dipole antenna!so。。。。。 :( sincerely beiga[/quote]
Hi,Eirp, Sorry , I have misunderstood your meaning,I 'll send it again! But I still can not agree with your opion,can you point out its derivation?
beiga
I can prove that your project is OK. Farfield and directivity is right. Derivation is show in Element's slide. Beiga, trust us Best regards, Eirp
Hello,Element7k&Erip, I am so sorry to bring you so much trouble on the question,I have not known where the error exists in untill you tell me.I am so ashamed of confusing the two concept:directivity pattern and directivity coefficient. THANK YOU!THANK YOU SO MUCH!for your help! But I still could not help laughing when I realized my simulation was right! :P If you have anything I can help,please tell me ,I will try my best! (contact with me as possible: my e-mail:beiga@163.com) best regards yours beiga
Hi Beiga, glad to be of service. :) hope you'll become a C/S/T expert and help many others in future. I will be interested to know what kind of antennas are you actually working on. We can swap knowledge. Cheers, Element7k Hello,Element7k&Erip, I am so sorry to bring you so much trouble on the question,I have not known where the error exists in untill you tell me.I am so ashamed of confusing the two concept:directivity pattern and directivity coefficient. THANK YOU!THANK YOU SO MUCH!for your help! But I still could not help laughing when I realized my simulation was right! :P If you have anything I can help,please tell me ,I will try my best! (contact with me as possible: my e-mail:beiga@163.com) best regards yours beiga
Hello,Element7k&Erip, I am so sorry to bring you so much trouble on the question,I have not known where the error exists in untill you tell me.I am so ashamed of confusing the two concept:directivity pattern and directivity coefficient. THANK YOU!THANK YOU SO MUCH!for your help! But I still could not help laughing when I realized my simulation was right! :P If you have anything I can help,please tell me ,I will try my best! (contact with me as possible: my e-mail:beiga@163.com) best regards yours beiga Hi,Element7k, I am working on a SPA(switched parasitic antenna),what are you about? by the way,what do you think of the CST precision? Do you have the FEKO?I want to compare them in speed and precision. beiga
Hi Beiga, SPA 8) in what freq areas and 4 what application? 4 me quite general, but mainly antennas for consumer products. CST precision is well documented in many journals and papers. However, the methods of achieving this precision is not. So you decide. if you are a student, you can go to www.f/e/k/o.co.za and request for a free evaluation copy of F/E/K/O 4.1. If financially possible, please ask your institution to buy it. It can be purchased at a very attractive rate. F/E/K/O 4.1 comes with certain new features and has improved interface over F/E/K/O 4.0. It even come with a webmovie example to get you started. The limited evaluation (F/E/K/O lite) should not be a problem if you are just simulating a monopole F/E/K/O works best if your model are mostly metal and does not have a lot of inhomogeneous materials. For you info, it comes with an example of a monopole modelled with a UTD gnd plane. Cheers, Element7k
I just love this forum. I was in need of a project file that clearly demonstrated a monopole antenna using discrete ports. Thanks guys
