Dimensions in Antenna designer not correct

I am a newbie who has just installed Matlab and have the Antenna Designer Add-on.

My first exercise is a Log Periodic Antenna on PCB substrate.

I have set Frequency Range 20 MHz (I assume this is BW?) and Frequency 910 MHz.

Substrate 0.0016mm and impedance 50 Ohms

I am expecting Antenna size over 150mm but the entire antenna dimension shown is 36 x 24mm and element lenths (I assume these are in the array called "Arm Length" that starts from smallest to largest are only around 4-5mm

It seems when I select LPDA antenna it defaults to 5500 MHz on load with dimensions for that frequency, I change the frequency to 910 MHz and "apply" but the domensions do not update.

Any help much appreciated.

On a side not, the units are in metres but for UHF I would prefer mm, can you change the units?

Thanks

Answer 1

[Shashwat Bajpai]

You can change the dimensions according to the specifications you want. The Frequency Range is the range over which you want to analyse the structure similarly Frequency is the analysis frequency and not the design frequency. Since design function is not supported for LPDA you will have to change dimensions to reach the frequncy required.

Hope this Helps!

Answer 2

[David Huisman]

But the frequency is Greyed out.

With regard to dimensions, you are saying the software does not help design the antenna but only analysis a design you have already established? ie, I cannot put in parameters and the software provide the antenna dimensions

[Shashwat Bajpai]

The design functionality is not supported only for a few elements as they have a lot of dependecies and LPDA is one of them. The Design Frequency option is enabled for th majority of elements and you can input that to get the dimensions of those elements.