July General Meeting: Introduction to Antenna Modelling

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The next AREG meeting will be held on Friday 21st July, starting at 7.45pm at the Reedbeds Community Centre, Fulham.

We are pleased to announce that the speaker for the July meeting will be Paul Lawson VK5SL. Paul will be introducing you to the basics of Antenna Modelling, and will demonstrate how to get started using the 4NEC2 program to examine antenna performance (4NEC2 is freely available on the Internet). He will take 3 of the antennas that Chris VK5SA described in his wire antennas for beginners talk a few months ago and show how you can visualize their radiation patterns and what their characteristics are on various frequencies.

In particular, Paul will show you how to model a basic dipole, a Windom (OCF Dipole) and an inverted V antenna, explaining how to define these in the software, what the components in the software do and how to set them to produce useful models of how the antenna is performing. This will be a great simple introduction to the topic of antenna modelling.

For those who then want to delve deeper, Paul has agreed later in the year to run a tech night where more complex antenna modelling will be examined for those who want to take it further.

We hope to see you at the club on Friday July 21st. Doors open at 7.45pm with the presentation getting underway at 8.00pm sharp.

AREG’s New 160m/80m Contesting Portable Antenna – Progress

Update – July 12th: Mounting of the tuning capacitor and motor drive is complete. Just a few more things and we will be ready for final assembly and tune up!


A group of members inside AREG, inspired by Steve VK5SFA’s success with his transmitting magnetic loop antennas have banded together to construct for the club it’s own 160/80m TMLA, specifically designed to be portable. It is able to be knocked down into components that can be packed into the back of a station wagon.

Significant progress was made today in assembling the antenna as we had hoped to have it ready to try at the IARU HF contest next weekend. We didn’t quite make it unfortunately, running out of daylight before we completed construction. However, we are now planning another session next weekend with the goal being to have the antenna finished and ready to run for the Trans Tasman Low Band Challenge contest the following weekend.

The club’s version of Steve’s antenna is using LCF78 coax instead of the wave-guide, with the vacuum capacitor mounted inside a water proof ex-camera case (great for transport and moisture proofing). The frame is made out of laminated bamboo broomsticks and a timber hub arrangement with the frame held together through compression provided by 8 ratchet straps. The aim is for the antenna to be suspended from a tree (or trees) at least 1 loop diameter above the ground (to increase it’s efficiency). It has been designed to accept 400W input power as well to overcome the efficiency issues these antennas can have.

Today’s construction efforts were led by Steve VK5SFA, Grant VK5GR and Scott VK5TST. The project wouldnt have been possible without generous donations from Steve VK5SFA, Peter VK5KX and Trevor VK5YFR.

The next steps are to complete mounting the motor tuning drive, do some structural adjustments to the frame, assemble the coupling loop and then test the antenna. This work will be completed next weekend, so keep an ear out for us during the TTLBC Contest on July 15th on 160 and 80m using our Transmitting Magnetic Loop Antennas!