Antenna on a non-conducting box
I have an box made of a polymer material housing all of my RF, DSP and other components. I have to connect a 1 meter monopole antenna to the system inside via a hole on the box. Is there any way to figure out how the box could affect the radiation characteristics of the antenna without actually simulating it? So basically, I wanted to know the effects of placing a steel whip antenna on a non-conducting box. I do not have access to expensive software such as Microwave CST. I can however gain access to ansoft.
Thank you
The monopole needs some really large ground to work properly. From what I understand, you only have a small box and the monopole, with no "large" ground?
You have no use of a length that is longer then your ground. Besides less good RX antenna performance will wrong impedance matching result in reflections if it also is a transmitter in the box as transmitted RF power will reflect back in your DSP and other electronics, causing EMI.
A monopole antenna is always a dipole but ground is assumed to be big and stable enough to act as a mirror for the invisible part of the dipole antenna. You have less need for expensive software as this software assumes that you already have antenna knowledge. You need a tool to measure antenna impedance and design a properly feed dipole or loop antenna to avoid wasted RF energy (both TX and RX). In worst case can reflected RF energy kill your DSP or causing random bit errors. If you not have any RF tools or knowledge how to handle them, buy a correct designed dipole antenna for which its radiation characteristic not is depending on the shape of the box.
If you need an uncritical antenna for a FM receiver, use any whip as antenna. Radiation characteristic will then much depend on environment of the box, if it placed on a metal table or handheld and such.
I have access to network analyzers, a Rhode and Schwartz spectrum analyzer, signal generators, etc. Also, I have PCB boards in the box and so I thought I could connect the antenna to the common ground for the board. So the ground, I guess is around the dimensions of the box, which is the size of a textbook.
What brand and type of analyzer? I ask because you then maybe have good use of this impedance matching software. Correct used can this software be a good help to solve problems related to unwanted reflections and optimize antenna function as good as ground plane allows it to do even if a too short antenna is used (monpole+ground length). Effective antenna efficiency is however still limited due to the size of ground plane, in case that it is much shorter then actual wavelength but with aid of this software can losses be reduced as far as possible.
One thought: When you connect the measurement equipment, you need to be careful not to change the antenna ground situation (by connecting all the devices ground to the antenna ground).
Coming back to your original question:I believe that the box material is a non-issue, and the real problem is the small ground.