Archive for October, 2009

Version 1.4 released!

Wednesday, October 21st, 2009

To all our blog subscribers and those of you who might not be aware, we recently launched Antenna Magus 1.4.0. Version 1.4 includes 6 exciting new antennas and you can now export corrugated horn antennas to a third export tool, TICRA’s CHAMP. Read more about Version 1.4. in the latest Newsletter 1.4.

Newsletter 1.4 preview

Newsletter 1.4 preview


Author: Robert Kellerman

Cylindrical dipole antenna with quarter-wave balun feed

Wednesday, October 21st, 2009

We just released Antenna Magus 1.4 with six new antennas included in the database.? All the new antennas are worthy of having a blog written about them but the Cylindrical dipole with quarter-wave balun feed really caught my eye. It is a very sturdy, simple but very useful antenna that you can build using very simple materials – a copper pipe, a metal plate, some solder and a piece of coax.

The fact that the balun is included as part of the Antenna Magus design is very useful. The ?ground plane? actually acts as a reflector, generating a 7 dBi directive gain and an operation bandwidth of approximately 30%. The antenna can easily be arrayed to form a robust base station antenna with beam-steering options (depending on how you excite the elements).

Our antenna design engineers had great fun fabricating one of these antennas for measurement purposes – as there were no published measurements available that could be used to validate the antenna CEM models and design algorithms. ?This antenna is so simple to construct that the job was done in a few hours using copper pipe from an air-conditioning company down the road! Most antenna design engineers these days never get the chance to get their fingers dirty with soldering and cutting pieces of metal and copper?although we all love it!

Photo of the fabricated Dipole with balun feed.

Photo of the fabricated antenna.

Comparing Antenna Magus results with measurements.

Comparing Antenna Magus results with measurements.


Vertical cut plane sketch showing semi-rigid inside copper tube

Vertical cut plane sketch showing semi rigid feed inside copper tube


Author: Robert Kellerman

The PACMAN antenna

Monday, October 5th, 2009

When I came across the Pacman antenna or Circular edge-fed antenna with sectoral slot, it immediately caught my attention as it reminded me of my very early gaming years. Although the only similarity between the antenna and the game is its appearance, this antenna has some features worthy of note. One very useful feature is that (although it is fed with a microstrip line) it requires no matching section. By adjusting the sector angle and size (shown in the image below) the real impedance can be adjusted from 50 ? to 200 ?.

Circular edge-fed antenna with sectoral slot.

Circular edge-fed antenna with sectoral slot.

When comparing the Pacman antenna with the Circular inset fed patch it seems to have some definite advantages at lower (+- 50 ?) real impedances. Firstly, the Circular inset fed patch needs a very deep inset to achieve 50 ? and the impedance becomes very sensitive to minor physical changes or manufacturing tolerances. Secondly, when using low permittivity substrates the feed becomes very wide at 50 ?. This has a significant impact on the physical shape of the Circular inset fed patch, but relatively little impact on the edge fed Pacman antenna.

I?m wondering if one can?t manually adjust the impedance by changing the sector angle with a sliding device (almost like with a potentiometer, or variable resistor). Has anyone tried this?

PACMAN


Author: Robert Kellerman