Dipole or wire HF antenna

[Sprint]

I'm interested to know what folks are using to receive HF mil & aircraft comms.

I just set up a Par End 45' sloped ant. My secondary has been a 5/8 wave 10 meter vertical. What's surprising is that often the vertical will "hear" and the wire won't. However, the wire is much quieter for obvious reasons.

Keep in mind these are vertically polarized signals in the 2 - 20 MHz range.

Icom HF gear....

Thoughts and comments.....

Cheers

 

[KMG54]

My par end fed did ok with HF milcom,but I changed out the 45 foot wire with about 400 hundred foot of 17Ga. electric fence wire {cheap at tractor supply}. I grouned the sheild terminal to my house ground and now I can recieve signals halfway ariund the world with no problem. Betwwen Offett, Andrews and Peurto Rico I have to turn the volume and gain down to here them clearly otherwise they come in so strong they distort.Also I here aircraft calling mainsail multipul times for a radio check before anyone responds.That could be the norm, but I think a base would respond instantly if they heard them.

 

[Sprint]

That's a wicked run of wire !! Sadly I don't have that much space. Did you find the Par was directional at all ? Mine is west to east with east being the feed end.

I've been trying to hear UK SAR on 5680 and can imagine that you may copy them just fine.

 

[KMG54]

Not really sure on the direction I only ran the supplied 45 foot for a day. I set the long run up in a L shape leaving the house at a south to north run of about 150 foot then nortwest to southeast for final run. I will check taht freq in just a little bit and let you know what I get.

 

[ka3jjz]

I would expect the PAR as a sloper would only have some directionality on some frequencies, depending on the angle the signal arrives, the frequency and height of the antenna from ground at its highest point, among other factors. That might be one reason why a particular signal is heard better on a 10m vertical and not on the PAR, but that's pure speculation. And on freqs between 2-20 mhz it's quite hard to predict what polarization is predominant since it likely gets flipped all over the place when it propagates.

best regards..Mike

 

[ka3jjz]

Take a look at the plots given in the manual for the sloper. At the tropical bands, it's nearly omni - but as the frequency rises, a slight dent starts to show, and at 25 mhz, you have distinct lobes in a cloverleaf like pattern.

Now purists will say that we don't have enough information here about mounting, ground conditions, height and so forth - and they're right - but the plots suggest that as a sloper, the higher in frequency you go, the more directional it becomes

best regards..Mike

 

[Token]

Take a look at the plots given in the manual for the sloper. At the tropical bands, it's nearly omni - but as the frequency rises, a slight dent starts to show, and at 25 mhz, you have distinct lobes in a cloverleaf like pattern.

Now purists will say that we don't have enough information here about mounting, ground conditions, height and so forth - and they're right - but the plots suggest that as a sloper, the higher in frequency you go, the more directional it becomes

This is going to be true for pretty much any wire antenna. As you said, it is impossible to get precise with what to expect because of all of the unknowns here. However, as a general statement the longer the wire in relationship to wavelength the more it will display directional tendencies.

Typically beyond about ½ wavelength straight wires will start to display notches or nulls in the pattern in the cloverleaf pattern Mike mentions above, beyond ¾ wavelength the notches start to become fairly deep. Beyond 1.5 wavelengths these peaks and nulls can become very sharp (the longer the wire, in wavelength, the sharper), and this is a core principal that makes directional wire antennas like the V-beam and Rhombic possible. It also plays heavily in the function of a Beverage antenna.

Remember, this length to directionality function is related to wavelength. So that a 45 foot end fed straight wire antenna might be considered omni-directional at 3 MHz (of course, there is “texture” to the pattern, not truly omni, but pretty close), as it is less than 1/6 wavelength at that frequency, but at 28 MHz it would be over 2.5 wavelength and would have distinct directionality.

With this in mind planning the location and direction of your wire antenna is pretty important. People often think about putting the broadside of a wire antenna in a desired direction, and this works very well for a single band dipole installation, but if they use the antenna for broadband purposes they end up with a null in that desired direction at higher frequencies. For that reason I often lay out wires I intend to be broadbanded with areas of interest about 45 degrees off the end of the wire.

T!

 

[SCPD]

Keep in mind these are vertically polarized signals in the 2 - 20 MHz range.

Polarization is not really an issue, unless you're keen on receiving signals under 3 Mhz. Once the signal refracts off the ionosphere, the polarization is more elliptical. Generally, this is why horizontal antennas are used above 7 Mhz.

From personal experience, one very important factor in a horizontal antenna is height. Using a dipole that is 10ft high versus 50ft high can make a dramatic difference.

FYI -- A solid receiving antenna for HF is a loop. Wellbrook or PixelSatRadio make a decent loop but they are not cheap. I just received mine late last year and am very impressed. I was very skeptical that this 3ft aluminum hulu-hoop could really work -- but it does -- and quite well.

 

[w2xq]

Well, if you want to play with the big boys below 7-10 MHz and have the room, my experience says a Beverage antenna is the way to go. Whereas Harold's original IEEE paper described his antenna as not expecting to work above what we call now the LW band or so, I found my 1000-foot Beverage off to the NE did a very nice job on 7 MHz long path over Africa in the early to mid-afternoon hours. During the twilight hours when layers start tilting at the grey line reflection points, I would often feed both a 125 vertical wire and the Beverage into the receiver at the same time. I never bothered with a loop on HF, but I built a 10-turn box loop for MW DXing... some 90 countries on 5 continents heard from NJ... and found the ability to null a signal (or local noise source) was equally (if not more) valuable than getting a signal peak.

 

[ridgescan]

FWIW I run a 100' wire configured as a horizontal "L" so 50' runs east-west, 50' runs north-south. That L wire is connected at one end to a d130j discone that I removed the skirt elements from and grounded to the fire escape system of my building which killed noise across the bands. My feedline runs through that d130j to the wire. I left the d130j with a 27mHz. vertical element in place because without it the L wire was way too noisy-lots of buzzing. I cannot explain why, but I figure it may be nulling noise from the power lines that run past that end of the antenna. All I know is it helped kill that buzzing. The antenna system is also grounded at the antenna switch here inside the shack, to a cold water pipe, which dramatically lowered noise in the MW/LW bands and further quieted the SW bands
As is shown in all the little videos I put out it does really well for what it is, and is a result of much much running up and down that ladder to the roof trying what worked and finding what didn't.
The one piece of advice I can give you through all of this is...whatever antenna you use, it is very important for you to give it a good reliable ground against RFI. SWL is all about your noise floor. Which is the reason for my oddball bastard antenna lol

 

[thomast77]

You probably need a ground. Depending on the radio you are using you can ground the shield on the connector going to the radio. Keep it short. or if using Coax ground the shield of the coax before it come into your house. That made a huge difference for reception on my Shortwave radio antenna

 

[Fast1eddie]

Hi, also using a Par in a sloper configuration as well. Do find it to have directional properties as any wire or dipole will. I will be replacing the wire with one longer but do not have the room for a 400 and something foot antenna. I envy those that do though.....Seriously, I am impressed with my Par, it's been up since October of 2007 with no problems at all. My grounding is set up to the shield, using a Icom R71A and getting excellent signals.

 

[KMG54]

Hi, also using a Par in a sloper configuration as well. Do find it to have directional properties as any wire or dipole will. I will be replacing the wire with one longer but do not have the room for a 400 and something foot antenna. I envy those that do though.....Seriously, I am impressed with my Par, it's been up since October of 2007 with no problems at all. My grounding is set up to the shield, using a Icom R71A and getting excellent signals.

It is nice to have the real estate to run a longwire. It does make a difference. I plan on adding a couple hundred more feet to make it close to a loop with out connecting. If that doesn't work well I will close it up and make a loop out of it and see what happens, Pratice makes perfect! It will be a couple of weeks though because this weekend I am heading to Daytona then a week back in the old stomping grounds of Stuart.

 

[SCPD]

I'm interested to know what folks are using to receive HF mil & aircraft comms.

I just set up a Par End 45' sloped ant. My secondary has been a 5/8 wave 10 meter vertical. What's surprising is that often the vertical will "hear" and the wire won't. However, the wire is much quieter for obvious reasons.

Keep in mind these are vertically polarized signals in the 2 - 20 MHz range.

Icom HF gear....

Thoughts and comments.....

Cheers

In response to your exact question, I think a 1m loop is the best performer on a cost-per-dollar basis.

The only catch to the above statement is if you're in a RFI-quiet location AND can get a dipole (or a vertical) up very high -- a 1/2 wavelength or more. The latter is not practical for most people and RFI-quiet is becoming next to impossible in a typical neighborhood environment.

A 1m amplified loop can be home-built with several plans floating on the internet; however, the two main commercial sellers work quite well.

The main attraction to the loop is that you can null out interference (with a rotator) in almost real-time and it's bi-directional at frequencies < 10 Mhz.

Both loops are solid performers. The Wellbrook 1530S+ has a hot preamp but the Pro-1B is a good competitor. Both do sell for quite a premium -- but their low-profile and interference rejection qualities can easily make up for it.

Active Loop Antenna ALA1530S+ N.American

Active Loop Antenna ALA330S N.A with PSU

Shortwave Magnetic Loop Antenna (Model: RF PRO-1B) | Pixel Technologies

FYI --

The 1530S+ is geared for high-gain, LW/MW and HF performance. If you want to listen to "everything" then this is the one to get.

The 330 model is geared for mainstream HF -- 2-30 Mhz and has a high-pass filter (attenuator) for the LW/MW bands.

The Pro-1B is similar to the 1530S+ but its preamp isn't quite as sensitive. The difference is small. The Pro-1B is slightly more expensive however.

PS. I have a Zero-Five 10-40 GP vertical antenna and both loops are equal if not better to this antenna below 15 Mhz. The vertical wins out (slightly) at the higher frequencies. Coincidentally, the cost of the vertical is equal to the loop but takes up 3x the space.

 

[k9rzz]

It all depends on what you're trying to hear. If your goals are more towards distant targets, then you need antennas that favor signals coming from low to the horizon. That could be verticals, vertically polarized loops, very high horizontal wires, beverages, or BOGs (Beverage On the Ground).

A simple delta loop fed on one of the sides can be an excellent low angle antenna without any special grounding system.

 

[k8mcn]

Take advantage of not a whole lot of real estate and put up a loop--i run 525 feet of 12G insulated wire in a loop--fits quite well in the back yard,not real noisy, hung in the trees for 3 years through ice, wind etc with no damage. The loop is 45 feet high (lucky for me lots of trees). I feed mine with 450ohm ladder line into a Palstar tuner---since you arent transmitting you could just as easily run it with two legs of 75 ohm coax, tie the ground together and using the center wires to attach to the loop...if you still use a tuner to get close to resonance on the milband i bet you'll love it with the added benefit of being versatile for other bands, and you wont have a ton of money in it compared to the "store bought" ones.

 

[N1BHH]

I used to do lots of VLF and MF listening with a 1200 foot wire only about 7-8 feet off the ground. I had two buried coax feed lines, one for my 80/40 dipole and the other was for the long wire. I bought a partial spool of #22 silver teflon jacketed at a ham flea market and just walked out thru the woods pulling the wire over easily reached branches. I have moved from there and took the wire with me and subsequently lost track of the spool.

For VHF and UHF I have a variety of quarter wave and scanner friendly antennas. One quarter wave VHF whip on a mag mount on my air conditioner does wonders for UHF military stuff. I have an off center fed dipole for 80 meters up 40 feet and soon to go higher, which does well for all my HF needs when not on the ham bands. And a couple more in the planning stages.