Is length of antenna for MF/HF frequencies (Rx only) important?

[settlednomad]

Originally Posted by conachair

Fantastic fun to have a play with but for being useful on a boat unfortunately they don't go low enough to receive weatherfax - something very high up the list for a long distance boat IMHO.

Lots of "my radio is best" out there This is mine
No need for a tuner.

Degen DE1103 Product Reviews

Some of these SDRs have a 'Ham it Up' option (slightly more expensive) which then gives it a frequency range of 100khz - 1.7ghz, like this one for example:

https://www.amazon.co.uk/gp/slredire...getName=sp_btf

Originally Posted by s/v Jedi

There’s no way around it... you’ll have to start with morse code at 8wpm, then go from there [emoji23]

There was a time when I was serving that I could have! Today I simply drum my fingers on the table trying to figure out stuff...

Originally Posted by El Pinguino

Its very easy to overthink some stuff....

My view....

I would simply buy a Tecsun 680 from a reputable dealer such as Anon-co on Ebay... https://www.ebay.com.au/itm/TECSUN-P...AAAOSwstxVPe6H
or if you are ' in funds ' spring for the 880.

Both excellent radios for SSB and general shortwave work. Plenty of reviews out there. On passage in temperate climates ( dream on Pingo!... ) I will often have one under the dodger at night tuned into RNZI on just the whip.

Plenty of reviews of these radios out there .

Both work good either on the whip or with the 'long wire' that is included.. same same this one https://www.ebay.com.au/itm/EB-Hot-T...wAAOSwu4BVr1ZN

First pic.... just received on my 880 using the AN-06 wire... conditions are somewhere south of shocking just now... this usually works well.

Second pic.... also today...same radio 880 hooked up to something fancier... one of these - https://www.gwhip.co.uk/receive-only-antenna

I use cocoamodem2 cocoaModem on a Macbook Pro feeding the signal in through one of these... https://www.ebay.com.au/itm/Sabrent-...4AAOSwT6pVo7Dh

KISS.. keep it simple, sailor!

A similar set up on Youtube is what got me started on this road, here:

https://www.youtube.com/watch?v=l1QyDVgclto

.

He was using a Sony SW radio connected with some of the bits you have mentioned above. I didn't realise such simplistic measures were available! But it got me thinking - just how good is it? That's when further research revealed the SDR dongle (in fact I think the dongle solution was posted in a comment to his video).

I think it is fair to say that one of the most important pieces of information we require when at sea is weather. Now, if I can get that, regularly and in almost all locations worldwide, then a simple and cheap set up has to be the way to go? You could even carry two of each at those prices for ultimate redundancy!

But in all seriousness, I don't want the complication of an all-singing-all-dancing rig, with insulated this and RF burn that, just to receive a weather fax that I could quite easily get on a little SW radio in between The Archers and Bon Jovi. And I certainly don't want the cost of such a mammoth set up! Horses for courses I guess. Though if my next boat comes with one already installed, then I shan't take it out!

I must say, though, this is certainly the place to be for learning stuff!!

Thanks all, some sound advice...

[conachair]

Originally Posted by settlednomad

Some of these SDRs have a 'Ham it Up' option (slightly more expensive) which then gives it a frequency range of 100khz - 1.7ghz, like this one for example:

Yep, but for that price you could actually get a decent SSB receiver

I've actually got a fun cube dongle pro plus which hopefully will be set up to automatically receive wfax into a raspberry pi some time. Had it running on openplotter but stutters bit, maybe on a clean raspbian it might be OK.

Still wouldn't want to head across and ocean without the trusty degen1103 & a few ways to decode the wfax though.

[settlednomad]

Originally Posted by conachair

Yep, but for that price you could actually get a decent SSB receiver

I've actually got a fun cube dongle pro plus which hopefully will be set up to automatically receive wfax into a raspberry pi some time. Had it running on openplotter but stutters bit, maybe on a clean raspbian it might be OK.

Still wouldn't want to head across and ocean without the trusty degen1103 & a few ways to decode the wfax though.

I don't know why but I assumed that a Degen 1103 was some permanently installed boat radio!! Ummm, slightly out on that one

I have just read a few of the reviews - it seems to work exceptionally well (more so in the areas I want it to!). And the price... great value for money it would seem. Further reading and comparisons required

[El Pinguino]

For what you are considering I don't think I would bother with dongles...... and yes I have a box full of them... all good fun but more of a hobbyist sort of a thing.

Just use your portable radio as an RFI sniffer....

I can't comment on the Degen as I have never owned one but in suggesting the Tecsun 680 or 880 I'm not saying that my radios are best but that they are the best of my (portable) radios

One feature I like ( unrelated to SSB and Fax ) is their ATS tuning system.... press the button and they will scan and store everything they can hear on the broadcast bands.. makes finding something to listen to muy facil.

They are on a par with my other portables technically but the easiest to tune on SSB... esp the 880. The Sony 7600GR, Sangean 909, and my Grundig G6 are all good but fussy to tune.... and the Sangean 909 is as deaf as a post on HF without a longwire.

[settlednomad]

Originally Posted by El Pinguino

For what you are considering I don't think I would bother with dongles...... and yes I have a box full of them... all good fun but more of a hobbyist sort of a thing.

Just use your portable radio as an RFI sniffer....

I can't comment on the Degen as I have never owned one but in suggesting the Tecsun 680 or 880 I'm not saying that my radios are best but that they are the best of my (portable) radios

One feature I like ( unrelated to SSB and Fax ) is their ATS tuning system.... press the button and they will scan and store everything they can hear on the broadcast bands.. makes finding something to listen to muy facil.

They are on a par with my other portables technically but the easiest to tune on SSB... esp the 880. The Sony 7600GR, Sangean 909, and my Grundig G6 are all good but fussy to tune.... and the Sangean 909 is as deaf as a post on HF without a longwire.

Hey Pinguino,

Those weather fax images you uploaded in an earlier post, especially the second one, look spot on.

I have just spent a couple of hours looking at different radios that would work. There are many! They all seem to have good reviews and they all cover the necessary frequencies required for weather fax. The most obvious difference I can see is the price. Obviously now, the question is this - does price equal quality and/or capability? Looking at the Tecsun 880 and the XHDATA D-808, they are similar in so many ways yet here, in the UK at least, the prices are worlds apart (£189 vs. £65 respectively). Incidentally, the Tecsun 880 in the US is only $159, so not fair!!

Aren't radios a bit like women, temperamental at times with some annoying little mannerisms? In the end we get used to them, or shell out a bit more dosh trying to keep it going for sentimental reasons before eventually giving up and getting the latest model from the store on the greener side of the grass

No decision as yet...

[plebian99]

You want to open another "yacht ground " debate? Lets not go there. But if you want to put your "balloon" into a packet and called it a "Kiss magic Balloon" you will have sailors swearing that you have a miracle invention that works. Much like the magic wire on ebay that comes in the packet, dipoles in packets are big business!

Originally Posted by Robert Tilbury

agree 100% but then we need a 145 page detailed paper on what an "UNUN "
Then the confusion with a "BALUN"

then next (and this would be great )

They would all get there HAM licence ,

Cheers
73`s
VK2LOZ

[plebian99]

No The Single radial is connected to your TUNERS grounding lug or bolt. You backstay or rigging wire is connected to the antenna terminal. Just think of it as an L or bent dipole. Its nothing more than a counterpoise, but in reality its a bent vertical dipole that is fed on all bands.

The critical point is that your rig or rigging must not be grounded.

If you feel uneasy about ungrounding your rig you can do this.

Same deal. Run a single wire from the stern to bow. Attach your forstay at the bow to the end bow end of this wire. The stern end of this wire is connected to the grounding lug of your tuner. You then connect the backstay to the Antenna terminal of the tuner. What you have created is a crude loop antenna, thats corner fed and is essential a vertical polarised antenna. It will work.



All of the above I have tried and both these antennas do work.

Originally Posted by Rorzech

This radial you run from bow to stern. Are the ends connected to fore stay and back stay ?

[El Pinguino]

Originally Posted by settlednomad

Hey Pinguino,

Those weather fax images you uploaded in an earlier post, especially the second one, look spot on.

I have just spent a couple of hours looking at different radios that would work. There are many! They all seem to have good reviews and they all cover the necessary frequencies required for weather fax. The most obvious difference I can see is the price. Obviously now, the question is this - does price equal quality and/or capability? Looking at the Tecsun 880 and the XHDATA D-808, they are similar in so many ways yet here, in the UK at least, the prices are worlds apart (£189 vs. £65 respectively). Incidentally, the Tecsun 880 in the US is only $159, so not fair!!

Aren't radios a bit like women, temperamental at times with some annoying little mannerisms? In the end we get used to them, or shell out a bit more dosh trying to keep it going for sentimental reasons before eventually giving up and getting the latest model from the store on the greener side of the grass

No decision as yet...

Those fax that I picked up today were pretty rough..... but I thought I would put up something fresh.... conditions are rubbish just now.... this is what you can get when conditions are good..

Prices? In the UK radio stuff always seems expensive... don't know why. I have bought a lot of kit from anon-co on ebay.... https://www.ebay.com.au/itm/TECSUN-P...0AAOSwgQ9Vloag

I don't think I would be comparing the XHData with an 880 but then I have never seen or used the former... this is a good site for comparisons, reviews etc https://swling.com/blog/2018/01/comp...-on-shortwave/

[plebian99]

All good points.

The point was not about trying to find a "magic length, it was trying to find a compromise antenna length with a reasonable radiation pattern from say 4 to 14mhz without introducing high angle lobes. At some frequency you will be close to the ideal quarter wavelength on most other frequencies you will be short or longer. 5/8th on 14mhz was used as a upper limit so that you dont destroy the pattern on 14mhz for ham and Pacific Seafarers net reliable long distance high performance antennas. A 5/8th low angle radiator is a spectacular antenna over seawater.

Why would you want a directional antenna? You dont, but the reality of the interference from the mass of rigging wire causes pattern distortion. Using antenna modelling its easy to create a system that kills the directional pattern that comes from the influence of the rig. De-tuning the rig to make it invisible is just too technical for most sailors.

The attached thumbnail is a model and the red lines zoomed shows the current on the rigging wire thats induced from a 40ft backstay onto the rig. The other is the radiation pattern. Just by connecting the ground wire to the mast I can have a uni-directional antenna with 3db of more gain. This is more for hams who really want to have a big signal back home from the yacht.

Unfortunately due to the influence of the rig and rigging wire, calculating the 1/2 wavelength high impedance point is just about impossible. You will be close to 1000 ohms off from my experience. This can be an advantage on some yachts because it move the high impedance point far enough away from most marine frequencies. Anyway there is no textbook answer to these problems. SSB guides are deluding people by telling them to use a simple formula to establish the half wave impedance point. Its not about winning the argument but being a realist about the environment on a yacht and all the disturbances caused by the rig and rigging wire. Substantial current flows in these wires despite not being part of the antenna

So long as we know where we going with planning an yacht install these problems are all minor and can be easily addressed.

Originally Posted by Cpt Pat

If you ever want to see an endless debate, find


To answer your question about antenna length: the most efficient non-directional antenna (I can't imagine why you'd want a directional antenna) is a 1/4 wavelength vertical antenna with at least a 1/4 wavelength horizontal ground plane. But you will probably want to use that antenna on multiple wavelengths. So... there is no "correct" length. Those of us who need to transmit have to avoid lengths that are multiples of 1/2 wave because a 1/2 wave antenna cannot be coupled through an antenna tuner (it has infinite impedance). But that too is not a problem for you to worry about.


I encourage you to simply experiment. Since you aren't transmitting, you won't damage anything. I've seen people hoist a wire antenna in the rigging, or run it along the mainsail leech - but if your topping lift is wire it will "couple" and degrade performance. I've seen people put insulators on their topping lift ends and use that as an antenna while using the boom as a ground plane. I've seen people fly a wire antenna with a kite (stay away from power lines!). The kite idea has the merit of allowing adjustment of the antenna length to the frequency. I personally use a delta loop antenna that utilizes my entire rig (A Simple Delta Loop Antenna for Smaller Vessels). I don't claim it's "optimal", but it works quite well.


Your ground plane is just as important as your antenna. Unless your boat has a steel hull, you will probably need to improve it. Start by using your DC negative bus as "ground." I personally trail a 50 foot stainless steel flat braided strap "ground" off the stern that's electrically connected to my DC negative bus and wire standing rigging when I need real performance (and during thunder storms). You can get that from American Grounding Systems (Ground straps and braids, ropes & wires by AGS. Online Catalog and Custom Design- SAMPLE REQUEST -tinned and bare copper, nickel plated copper, stainless steel, braided ground straps).


I suggest just trying something that's mechanically convenient and then tuning around to see if it works. Maybe use a clip lead and just start clipping it around. Try the shrouds and stays for starters. There is an excellent set of "beacon" transmitters on 2.5, 5, 10, 15, and 20 MHz: WWV and WWVH. If you hear a male voice announcing each minute - you are receiving Colorado / a female voice is Hawaii.


Finally, a point made above deserves more comment: interference will be your worst enemy. It'll make weather faxes look like trash. Once you have good reception, I suggest turning on any LED lights you have - one at a time. If you are very lucky, one on more of your LEDs won't wipe out the entire HF band (and maybe VHF as well). Radio Amateurs are finding the HF band to be practically useable from November through early January. The reason: LED Christmas lights.

[Northbound44]

I have the almost perfect installation on my boat and I am always surprised to see how less than acceptable installation performed amazingly perfectly.
The cheapest installation I saw simply used a 12 Ga wire suspended by the halyard used as the antenna and the stainless steel lifeline around the boat as a ground plane.
I can also confirm that you can use only a small suspended wire without tuner and or ground plane if you’re interested only to receive without transmission. In addition, you can use any metal tank in your boat as ground plane. Contrary to popular belief, the ground plane doesn’t have to be in direct contact with the seawater, since the transfer is done by capacitance with the metals object close to the fibreglass hull. Obviously, there is no issue with metallic hulls.

[plebian99]

Well if we deal with the facts its not hard to understand why less than perfect installations work over seawater.

Most installations that have problems have more to do with the way the antenna is fed rather than "grounding" problems. If you concentrate on what kind of antenna you are feeding and what type of feed system that you are using you can make anything work. Ground loss over seawater is practically zero putting a copper mine into the bilge wont fix anything.

All backstay antennas are random wire length antennas that can behave well on 1 or 2 frequencies and be a nightmare antenna to feed on other frequencies. When you concentrate on the feed system you can easily understand the resulting antennas performance and any associated problems like RF feedback or common mode noise.

Over seawater even a light globe connected to the antenna tuner terminals will make contacts. Making contacts does not infer best practice or that something new has been discovered.

You simply cant beat the performance of a well designed vertical antenna operating over seawater. Likewise going from a single radial wire to the very best ground that you can install on a yacht will essentially buy you nothing because there is no loss to combat. What the ground might fix or move is the poor feed or antenna impedance that might lower loss from the antenna tuner producing a lower loss match. What yachts people find as acceptable performance from their installations would be considered bad performance from a hams or a professional HF users perspective. That is not to say that these inadequate installations do not perform adequately for coastal and emergency communications.

The attached picture is the radiation pattern of a backstay that was optimised for 14mhz. Notice the directional pattern. This pattern can switched on and off just by grounding the rig with toggle switches. This effectively gives this ham a directional antenna on a 10 meter yacht whose pattern can be switched. Most stations report 10 db advantage to this directional pattern change. The second picture is of the resultant radiation pattern. Max radiation fires backwards towards to the stern. Lots can be done with a humble backstay to make it an killer antenna.

Originally Posted by Northbound44

I have the almost perfect installation on my boat and I am always surprised to see how less than acceptable installation performed amazingly perfectly.
The cheapest installation I saw simply used a 12 Ga wire suspended by the halyard used as the antenna and the stainless steel lifeline around the boat as a ground plane.
I can also confirm that you can use only a small suspended wire without tuner and or ground plane if you’re interested only to receive without transmission. In addition, you can use any metal tank in your boat as ground plane. Contrary to popular belief, the ground plane doesn’t have to be in direct contact with the seawater, since the transfer is done by capacitance with the metals object close to the fibreglass hull. Obviously, there is no issue with metallic hulls.

[settlednomad]

"Are you using a sacrificial anode for a ground? Usually at the bottom of the boat if it is a metallic hull.

If your radio is independent from the boat (batteries) then you should make sure it is grounded (if plugged into ac this should work). If it is not and is connected into DC then there should be a ground point on the boat that would work.

The antenna is much of a muchness. As it is just a receiver there will be no coupler and the antenna should be cut as close to the specific length of frequency you are trying to receive. Best to get a full wave receive if you can but if not ½ wave or ¼ wave.

@ 22mtrs you are good for a receive frequency of 13.5Mhz.

I would suggest that this would change in orientation dependent on your location relevant to the transmitting station. A vertical wire or sloping wire (45 degree angle) would be good. You could even whip up a droopy dipole with this from bow to stern although you may need two sets of wires for this.

The Balun is designed to have two conducting lengths (1 which is positive and 1 which would give you the full wave) for receive.

But I am guessing space is not your friend unless you have struck it rich."

The above is an excerpt from an email I received from a friend (we served together). I had shown him the gucci-looking wire assembly that was posted by El Pinguino. The friend is ex-mil who served all his time in a signals outfit. Since leaving he has become a system's architect for a major US military HF comms provider. He tests the systems all over the world for different armies who have also bought the equipment. He is not very boaty by nature but he knows most things 'comms'.

Interesting to read that even a small portable radio should be grounded somehow if it is used separately to the boat system. Is this something other users have subscribed to and enforced? Did it make a difference?

As for final antenna decision, I think I'll play around with a vertical/sloping wire for now and take it from there

[plebian99]

With due respect to your friend. On 13.5 mhz a 22 meter antenna will make a lousy antenna whose radiation angle is too high. I have attached a radiation angle plot of this antenna. The angle of takeoff is too high. It will only be useful as a good antenna below 8mhz. Thats not to say that it wont receive or pick up stations, albeit it rather poorly.

I would suggest a piece of wire 10 to 13 meters long. The second plot is of a 13 meter wire. As you can see the angle of radiation is much lower and will receive well from 2mhz to 15mhz with excellent performance. For weak signal weather fax and long range reception of distant SSB station this is the better antenna and much better radiation pattern

Your rigging and the amount of slope of the wire will affect the radiation pattern, the deviation from from ideal will be minimal impact on the takeoff angle.

The 3rd and 4th pictures below shows a 10 meter wire length on a "typical" 10 meter yacht. I also show the radiation pattern and you can see the affect that the rigging has on the radiation pattern. Regardless its a nice radiation pattern for long distance reception.

Feed it with a 9:1 UNUN and you will have a very nice all band receive antenna.

Radio is a science and you dont have to rely on hearsay and old wives tales that float around on the many cruising forums about supposed performance. Even ground efficiency can be modeled. And let me tell you that you dont have to buy or use a few pieces of wire stuffed up a hose pipe!

Originally Posted by settlednomad

"Are you using a sacrificial anode for a ground? Usually at the bottom of the boat if it is a metallic hull.

If your radio is independent from the boat (batteries) then you should make sure it is grounded (if plugged into ac this should work). If it is not and is connected into DC then there should be a ground point on the boat that would work.

The antenna is much of a muchness. As it is just a receiver there will be no coupler and the antenna should be cut as close to the specific length of frequency you are trying to receive. Best to get a full wave receive if you can but if not ½ wave or ¼ wave.

@ 22mtrs you are good for a receive frequency of 13.5Mhz.

I would suggest that this would change in orientation dependent on your location relevant to the transmitting station. A vertical wire or sloping wire (45 degree angle) would be good. You could even whip up a droopy dipole with this from bow to stern although you may need two sets of wires for this.

The Balun is designed to have two conducting lengths (1 which is positive and 1 which would give you the full wave) for receive.

But I am guessing space is not your friend unless you have struck it rich."

The above is an excerpt from an email I received from a friend (we served together). I had shown him the gucci-looking wire assembly that was posted by El Pinguino. The friend is ex-mil who served all his time in a signals outfit. Since leaving he has become a system's architect for a major US military HF comms provider. He tests the systems all over the world for different armies who have also bought the equipment. He is not very boaty by nature but he knows most things 'comms'.

Interesting to read that even a small portable radio should be grounded somehow if it is used separately to the boat system. Is this something other users have subscribed to and enforced? Did it make a difference?

As for final antenna decision, I think I'll play around with a vertical/sloping wire for now and take it from there

[settlednomad]

Plebian99 - I know the square root of naff all at the moment so all input is greatly received

[conachair]

Heres a load of radios to have a listen on

websdr.org