question about longwire

[Michiganrailfan]

As long as its horizontal, can a longwire for SW listening point in any direction? Or should it be perpendicular to the direction of signals you're trying to listen to?

Or does this matter?

Thanks

 

[ka3jjz]

Well, let's be clear here - do you mean an antenna that is relatively close to the ground, at least 1 wavelength long? That's a very basic definition of a longwire, a term that is unfortunately greatly misused. It's a totally different animal....the longer the antenna becomes, the more directional off its ends.

I suspect you mean something along the lines of a long stretch of wire or an inverted L as shown here (near the bottom of the article)...

Antenna Primer Part 1

And the answer is that the direction is pointed at is not really critical. What little directivity it might have will likely change with the frequency and height above ground. However I do know more than one DXer that will string 2 random wires - in opposite directions - to see if the signal is propagating better on one antenna than the other.

best regards...Mike

 

[k9rzz]

Good question! Prepare yourself for a dozen different answers.

My take - it depends.

How long is the wire? What frequency is it being used on? How high is it?

In theory - horizontal wires at least 1/2 wavelength long should show some directivity. The longer the wire, the more lobes in it's pattern it will have. HOWEVER, if it's less than 20 ft off the ground, it will probably be pretty much omni directional.

In practice - I have noticed some directional properties in 75 ft wires (short) up only 15 ft (low). If the wire is REALLY long (>300 ft) and merely laying on the ground - it will be directional off the far end that it's pointing.

Advice - string up as long of a piece you can - as high as you can - and don't sweat it. Advice #2 - you can't have too many antennas!

(insert smiley face here)

 

[ridgescan]

Yeah MRF if you have a length of wire up and it is not cut to any particular HF band it's called a "randomwire". Like I have 50' here and I have it faced eastwest. Given your location eastwest will be fine. I get a ton of good stuff most of which is at angles to the wire. Mine is 35' up too.
http://en.wikipedia.org/wiki/Random_wire_antenna

 

[Michiganrailfan]

Thanks for pointing me to the introduction on roaming times, Mike.

I'm wrong about the nomenclature. It's definitely randomwire, not longwire.

I'm not sure which band I should tune to. I'm a newcomer, and don't know much about what's to hear on the different bands.

I like the idea of stretching 2 random wires in opposite directions.

Thanks also Ridgecan for the link to Wikipedia.

Thanks also, K9rzz. I like the antennae on the photo of your car.

What I have is the following:

I'm very new to SWL but have been scanning a great deal for about 5 years. I just took ownership of a SoftRock Ensemble. It's a nice little piece of work. Right out of the box, I hooked it up to a discone antenna that I use for scanning. Lots of noise. Not very good reception on all bands.

Then, I found in my garage a spool of 100 feet of 12 gauge insulated copper wire (stranded). I also have several pieces of co-ax laying around from the scanner install. I ran a piece of coax (30 ft) to a little plastic junction box that lets me solder the 12 gauge wire to a panel mounted PL-259 fitting.

I placed the junction box near a basement window and stretched the copper wire outside. There, it goes vertically up to the railing of my deck. I stretched the wire along the railing (about 10 feet off the ground) and then back again. A Rube Goldberg job.

The results are amazing. Reception is still noisy, but I'm getting way more stations. Radio Havana, China, lots of Spanish speaking stations. Whats with all the religious stations? Where do they generally broadcast from? Overseas? Or here in the good ole USA?

For my next project, I want to stretch the copper wire directly east to some trees in the back yard. The property line is about 200 feet away from the house, and the trees are small.....lots of open air with no electrical wires around. I may go crazy and stretch another wire the entire distance. I'm even thinking of a loop someday. The best I can do is 10 to 12 feet above the ground.

From what I'm reading, I need to move the transition from co-ax to copper wire as far away from the noisy house as possible. I'm pondering how to do this. I don't want to use a shovel. And I haven't figured out the balun lesson yet.....not sure if I need one.

With my Rube Goldberg antenna on the deck, the waterfall on WINRAd shows many stations that are just too weak to hear clearly. There's still a fair amount of noise. I'm guessing the junction box is too close to the house.

I'll keep experimenting.

Thanks again, guys.

 

[k9rzz]

"I'll keep experimenting. "

Atta boy! That's the name of the game and how you'll learn what works and what doesn't.

Welcome to HF!

 

[kb2vxa]

"Good question! Prepare yourself for a dozen different answers."
There is one answer to the question, the others are tech heads so pick one. (;->)

So here's the skinny from a crusty old fart with more years of experience than you have been on the planet. (;->) Directionality isn't an issue, it's not a beam nor is it cut to any specific band, it's only a random length wire. Sure, it exhibits lobes in the H plane which is what they're talking about but being as random as the antenna wire they amount to nothing of any consequence.

"I'll keep experimenting."
And eventually you'll find the "frequency effect" difference between a very short and a very long wire. In between a wire is a wire is a wire when it comes to SWLing.