Tag: antenna

Starting HFSS

In our lab, we use a Red Hat 6 running HFSS 19 to do some antenna simulations. Getting this thing to work can be difficult, especially for non linux people (most people). In the future hopefully they just put windows on this machine, it’s a Xeos with lots of power so the hardware is worth keeping around.

Anyway, from May until this November when the license expires, to get HFSS running you have to restart the license server first. In HFSS 19 this is a session that connects to the server through your browser. To trigger this, use in bash:

cd /

cd ./ansys_inc/shared_files/licensing/

(use su or sudo) ./start_lmcenter

At this point it will do something and get stuck… so use control+c to kill that process and try to start the license manager center again. This time it should open firefox and you can press start. If you have internet connection, it should be running.

Next you might want to set up VNC server. On this machine it’s

vncserver :8 -name nick -geometry 1440×900

where you can change the desktop number, name, and geometry variables.

to get in, connect a vnc client to

129.xxx.xx.xxx:8

or whatever your desktop number is. You might be prompted for the password.

Planar Antennas

There is a special class of antennas known as planar antennas. Sometimes these are called microstrip or patch antennas. The key feature of these is that they can conform to a flat plane, or even a curved plane. This is a fascinating realm of antenna design.

Say you wanted to design a durable antenna that is small and can conform to the cylindrical body of a mortar shell, and report telemetry back to the base.

You want to design a patch antenna!

The most critical design parameter for patch antennas is called relative dielectric permittivity, given like e sub r here, often called keff.

The material between your ground and antenna affects the end result greatly! Common types of filling are silica and teflon fibreglass.

Head on over to microwaves101 if you want to learn more!