80m Vertical Loop Modelling on Other Bands
When you build an antenna like this one, even on a 1 acre lot, you have very little choice regarding which way to face the antenna. In my case, the only available space was along the longest boundary, so the directivity is whatever I got from that placement.
In a previous post, I modelled the antenna on 80m -the band for which it was designed. Here I model it for other bands.
40m summary
On 40m we have the main lobe at a very high elevation angle 54 degrees, but a substantial lobe at 24 degrees. The fours main lobes are at 45 degree angles to the axis of the antenna giving best propagation to the north and east, and almost as effective propagation to the south and west.
20m summary
On 20m we have NVIS (max gain at 58 degrees elevation). Although there is still a fairly large lobe between 15 to 35 degrees. The radiation is mostly broadside-ish at about 45 degrees -in other words to the north and east with smaller lobes to the west and south.
On 15m we have multiple lobes with the best directivity broadside to the north east and south west. Best gain is at 16 degrees elevation with multiple lobes at higher elevation angles.
10m summary
On 10m the pattern is very similar to 15m except the best gain is at a very low 9 degrees elevation to the north east.
80m Vertical Loop up again after Cyclone Yasi
Cyclone Yasi tore down my big 80m vertical loop, but I’ve got it back up again and set up a little better.
The configuration is a triangle with apex in the top of a very tall tree. The antenna is fed at a bottom corner using 450 ohm ladder line. The 450 ohm line runs across the garden from the 4:1 balun external to the house. Coax then runs inside the roof of the house to the rig.
The height and configuration is slightly different to previous, so I modelled it again in CocoaNEC.
I’ll present the modelling at the design frequency first, then on the other bands in another post.
80m elevation plot
Got to love 10.0 dBi at 20 degrees elevation in the plane of the antenna, so that is NW, SE. Good for SE Asia, Mediterranean, Europe, New Zealand, parts of South America. Not so good for North America unfortunately.
SSTV DX
I left my SSTV setup running last night- I forgot to turn it off- and I received these images. First time I have received SSTV from so far. USA and Spain.
82 Countries Contacted but only 37 Confirmed so far
I have actually made contact with 82 countries but they have not all been verified, especially not on eQSL. I use LOTW and paper QSL as well.
I’ve Got to Stop Putting Antennas in Trees!
Today I continued with the job list. The primary one was to hang the No 2 ZS6BKW Antenna. This antenna was always a bit short compared to ideal for 400 ohm ladder Line, so the first thing to do was lengthen it. Of course, I didn’t have what I needed to do that job, so a 30k round trip to the stores was in order. Then once lengthened the task of putting it up between the two trees began. My yard has a few more mature trees to get in the way, than it did when I first bought the place, so the task is more difficult. After umpteen tries, I decided the day was too hot for such foolishness, and I gave it away until 6pm when with one shot, much pulling of 300 lb fishing line, and lots more swearing than yesterday, I managed to get the antenna up in the air. Tomorrow I’ll test it.
2011 in review
The WordPress.com stats helper monkeys prepared a 2011 annual report for this blog.
Here’s an excerpt:
A San Francisco cable car holds 60 people. This blog was viewed about 3,400 times in 2011. If it were a cable car, it would take about 57 trips to carry that many people.
Some Jobs done today
Icom IC706MkIIG removed from the Nissan and replace in the shack.
Barrett 950 packed up to send to Barrett for repair.
ZS6BKW No 1 Antenna (random length dipole) rehung took three goes with the slingshot, a few tangles and some swearing.
ZS6BKW No 2 Antenna down for repair
Bushcomm Travelling wave antenna transferred over to HF APRS for now.
Icom IC703 reconnected to iMac for APRS duties (HF 40m)- so VK4MDX-4 back in to full APRS service on VHF and HF.
Old PC Hard drive dead- attempted recovery failed.
Latest build of Ham Radio Deluxe (HRD) installed on eeePC.
HRD Log updated from backup file.
Logbook of the World tQSL digital certificate replacement requested from ARRL- great friendly reply- certificate should not be too far away.
New iMac keyboard purchased and attached to eeePC- now all my keyboards “feel” the same.
