Good time to try to catch DX stations on HF is amateur radio contests on 20m during the day. This catch is from Acona, Italy, an Italian amateur radio club callsign. Here is my reception using 10ft of 18awg wire flopped out of the window. My location is in Central Oklahoma.
Propgtn DX from Italy on 20m Today
- Thread starter air-scan
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The Italians own 20 meters.
K4EET
Chaplain
Hello @air-scan, I saw your other post about buying the 40 feet (12.2 meters) of 18 AWG for USD $6.00 (€4.98) at Walmart. Post #8 in that thread by @ka3jjz mentioned the relationship of wire length to received frequency.
Just as an FYI to show you that your 10 foot antenna is not too far off, the formula for one leg of a dipole antenna (which is what you essentially have) is:
Using the received frequency of this thread, 14.257 MHz, we can calculate the correct antenna length as:
Rearranging the formula, we can calculate what frequency your antenna is theoretically best suited for:
Sooooooo... just a little math there as an introduction to radio theory. You have probably heard of dipole antennas which is your antenna with another leg running in the opposite direction of the same length. The formula for the overall length of a dipole is obviously then:
The only other comment I would make is this. Most HF signals that you will be listening to are horizontally polarized. In contrast, VHF and UHF signals that you listen to on a scanner are vertically polarized. That is why scanner antennas point up to the sky in order to better "catch" the vertically polarized radio waves. If a scanner antenna were in the horizontal plane, the received signal would not be as strong due to the polarization mismatch.
In your case for your shortwave receiver, ideally the antenna out your window should be horizontal. In your other post that I referred to earlier, @mmckenna mentioned they were using speaker wire for their shortwave/AM antenna. It is probably more horizontal than vertical, I would think. I could be wrong. As you have seen, it will still receive, just not as good. To overcome the polarization mismatch issue when I lived in a third floor apartment, I had my antenna running between the two furthest windows of my apartment. I had a friend hand out one window and I hung out a window at the other end and slingshot a tennis ball with fishing line tied through it to my friend with a baseball glove. That way, my HF antenna was horizontal with respect to the ground. I used 26 gauge enamel coated magnet wire that I had laying around. It was so thin nobody could even see it but it worked like a champ. Probably not the best price in the world be here it is from Amazon:
I hope you find this information at least a little interesting. You seem like a person that likes radios and likes to experiment. If you buy that one pound spool from Amazon of 26 gauge enamel coated magnet wire, you should have enough for years of experimentation. It doesn't say how many feet you get but it had got to be quite a few.
Cheers and 73 (best wishes in ham lingo), Dave K4EET
P.S.: Let me know if you have any questions...
P.S.S.: Happy DX hunting on the shortwave bands!
Just as an FYI to show you that your 10 foot antenna is not too far off, the formula for one leg of a dipole antenna (which is what you essentially have) is:
234 / f (MHz) = Quarter-Wave (feet)
Using the received frequency of this thread, 14.257 MHz, we can calculate the correct antenna length as:
234 / f (MHz) = 234/14.257 = 16.413 feet = 16 feet 5 inches
Rearranging the formula, we can calculate what frequency your antenna is theoretically best suited for:
234 / Quarter-Wave (feet) = f (MHz) = 234/10 = 23.4 MHz
Sooooooo... just a little math there as an introduction to radio theory. You have probably heard of dipole antennas which is your antenna with another leg running in the opposite direction of the same length. The formula for the overall length of a dipole is obviously then:
468 / f (MHz) = Half-Wave Dipole (feet)
The only other comment I would make is this. Most HF signals that you will be listening to are horizontally polarized. In contrast, VHF and UHF signals that you listen to on a scanner are vertically polarized. That is why scanner antennas point up to the sky in order to better "catch" the vertically polarized radio waves. If a scanner antenna were in the horizontal plane, the received signal would not be as strong due to the polarization mismatch.
In your case for your shortwave receiver, ideally the antenna out your window should be horizontal. In your other post that I referred to earlier, @mmckenna mentioned they were using speaker wire for their shortwave/AM antenna. It is probably more horizontal than vertical, I would think. I could be wrong. As you have seen, it will still receive, just not as good. To overcome the polarization mismatch issue when I lived in a third floor apartment, I had my antenna running between the two furthest windows of my apartment. I had a friend hand out one window and I hung out a window at the other end and slingshot a tennis ball with fishing line tied through it to my friend with a baseball glove. That way, my HF antenna was horizontal with respect to the ground. I used 26 gauge enamel coated magnet wire that I had laying around. It was so thin nobody could even see it but it worked like a champ. Probably not the best price in the world be here it is from Amazon:
I hope you find this information at least a little interesting. You seem like a person that likes radios and likes to experiment. If you buy that one pound spool from Amazon of 26 gauge enamel coated magnet wire, you should have enough for years of experimentation. It doesn't say how many feet you get but it had got to be quite a few.
Cheers and 73 (best wishes in ham lingo), Dave K4EET
P.S.: Let me know if you have any questions...
P.S.S.: Happy DX hunting on the shortwave bands!
15plus1
Member
delete
I seen other posts stating length of wire doesn't matter if its not being used for transmitting so I tested the theory and I do see results. Since portables overload Ill keep it no longer than 15 ft (19m band) and no less than 10ft (12m band but also okay for 11 and 10m) and save the telescoping whip for FM broadcast and airband. Really doesn't matter for 80m listening because that band is 1 hop and that 1 hop is the entire mainland of the USA I usually hear well any station in a QSO. Mostly Texas, Arkansas, Colorado, Kansas, Missouri, Oklahoma, and New Mexico. I have heard 9,3,6 and 8 areas.
Right now I don't have the tools to solder and nor willing to spend on them at this time. I wanted to keep it simple. I have alligator clips that work fine or strip the insulation and feed the bare wire into the gap at the base of the telescoping whip at just below the elbow or pivot point.
I had to know those antenna formulas when I used to have a technician class license which was cancelled in 2012 after expiring in 2010. No I am not renewing. Those formulas are in my brain like shadows in stone after Hiroshima. Thanks for your time and effort but I am sticking with what I got to work with for now.
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