Lower is better – now SWR 2.0 at 14.160. Moral: you would really prefer to have your antenna up in a tree.
What can we expect – some websites
DX Propagation: Maximum Usable Frequency predictions:
http://www.spacew.com/www/realtime.php
Sometimes you don't want DX, you want to make a more local contact. Critical frequency is what you want to know about...
http://www.spacew.com/www/fof2.html
Propagation forecasts are nice, but you can do more using
Internet tools...
RBN (Reverse Beacon Network) is a network of listening posts around the world that scan entire bands and decode and report digital (including CW) signals heard.
http://www.reversebeacon.net/
(Sorry, it doesn't work for voice modes, yet)
You can look for your own signal – the next slide is the result while testing indoor antennas at my house a few days ago.
After that we'll try it live... with some variations.
There is also a network of Software Defined Radios - the WebSDR. Here you can see a graphic display in real time of all the signals in a range of frequencies and you can select
any one signal and hear how it sounds at the distant site.
At http://www.websdr.org/ you can see all the sites available to choose from.
My favorite is a site in New Jersey, I sometimes monitor ourSnail Net by looking at this site:
http://96.225.100.244:8902/
(Note he is using a dynamic DNS service – his address may change from time to time
Before going on to part 2, try these things live on web:
(see whether 20 meters still open, maybe go to 40)
On RBN,
Look for my own signal as dx
Look for W1AW/1 or W1AW/5 as dx
Look at K1TTT as de
On WebSDR – see if we can be seen in NJ or somewhere else not too far
If not us look for something else – W1AW/* good bet
How it works: the voltage on a half-wave dipole is maximum at the ends. The current is lowest where voltage is highest and vice-versa. A quarter wave matching section transforms the high impedance at the bottom of the half wave to very low at the shorted end. By connecting the feed line at a tap on the matching section about 1/10th of the way from the low impedance end a match to the relatively low feedline impedance is made.
The Magic of the Quarter WaveA simple quarter wave vertical needs a ground connection. A quarter
wavelength radial is a virtual ground – the high impedance at the open
end makes the other end exactly equivalent to a connection to ground.
The ground plane antenna would work OK with just one radial, but
having more than one makes the directional pattern symmetrical.
How Long is a ¼ wavelength?
Quarter wave (ft) = 234 / freq (MHz)3.5 MHz 67'7.0 MHz 33'10 MHz 23'14 MHz 16'18 MHz 13'21 MHz 11'25 MHz 9'28 MHz 8'50 MHz ~5'
146 MHz ~19” 440 MHz ~6.4”
Multi-band radials – this is how Butternut suggests you can make a multi-band radial for the HF6V multiband vertical
antenna.
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