Portable antenna with gain

[hotrod]

Ok looking forward to seeing the next vid. Come on hotrod, northern is making a 2 element beam why would you even mention a a99, are you going to fit a parasitic element to it? His driven element alone would outperform the a99( if he changed the feedpoint back to centre fed). Actually fitting a reflector to a a99 might be a good project .

simply cause his fist post he said a PORTABLE antenna with gain. ya the a99
is a great portable antenna. yes it lacks gain. but i wouldnt call a 2 element
beam portable thats for sure.MAYBE a rotable dipole mounted flatside [sirio d27]
i wouldnt wanna build a beam even 2 elements whenever i wanted to talk

 

[Shockwave]

You're missing the chance to pick up significant gain if that water behind you is salt water. Nothing does for signal at HF what placing the vertical antenna directly over a salt water body does. Twenty years ago I took an Antron 99 out on the boat in Long Island sound with four 2SC2290's as the final stage. With the bottom of the antenna as close to the water as possible in a fishing rod holder, the results were impressive.

DX was rolling and Lady 50 at the Dragon base in Long Island had a larger Jo-Gunn and 1000 watts carrier. For a while it was neck and neck were our signals were close. Very surprising to me. Rather than take the time to make a short coax cable up that was needed to reach the antenna from the radio I just grabbed a 50 foot pre made roll off the shelf and went with most of it coiled up in the cockpit under the antenna.

After we tripped over it several times, I picked the wade of coax up and threw all the slack overboard. My friend who was on the radio at the moment was like "what the heck did you just do"? Apparently that last move brought everything up many db!!! Now the kilowatt carrier into the base Go-Gunn was way under the signal our 100 watt carrier was making.

Today I recognize that propagation and polarization shifts may have been contributing to having more signal than the horizontal beam. However, it doesn't change the fact that the near infinite ground plane the salt water added under the antenna made huge differences I could see in the RX. The coax was brought back onboard and thrown over several times to confirm not just a few db but at least an extra S-unit.

Imagine what one could do with a real ground plane placed over the salt water in those pictures. You'll need more coax but if you could just get it at least 20 feet offshore and use the water to replace the ground plane, you'll be amazed what one antenna will do. I'd use a 5/8 wave ground plane since they are most dependant on the size of the ground plane under them to lower their angle of radiation.

The trick is to mount the antenna on a pole that keeps the feedpoint as close to the water as you can but don't let salt water get on your matching network or insulator. The best bet would be to bend the radials down just enough to keep the last half of each in the water most of the time. If you could do that, you'd be impressed with the results especially in the direction away from the beach.

 

[northern35s]

simply cause his fist post he said a PORTABLE antenna with gain. ya the a99
is a great portable antenna. yes it lacks gain. but i wouldnt call a 2 element
beam portable thats for sure.MAYBE a rotable dipole mounted flatside [sirio d27]
i wouldnt wanna build a beam even 2 elements whenever i wanted to talk

Why isn't it portable something that is lightweight, can be carried in a rucksack, and takes me 10 minutes to erect, I'd call that pretty much portable, it's hardly permanent. I can take my backpack gear onto the beach and erect the antenna at the waters edge, even if I keep the gear very lightweight, one rig at 5-10W maximum, one LiPo battery, and I'll still have a good signal the other side of the World. I can pack it all away when done and still have room for sandwiches and a flask of coffee in my rucksack.

You must also remember why I'm building a 10m version, it's simply to test the theory, my main goal is 20m, that's bigger, more expensive, more to handle, if my early attempts with a 10m version pay off then I'll have a go at the 20m version.

The reason why here in the CB section and not the ham section, well the fact it's currently a 10m version and very little scaling required for an 11m version. Wouldn't you like almost amplifier like gain just for the sake of carrying a second lightweight pole rather than one? I know a chap who goes hill-topping in his car with a drive on mount, 20' pole and 2 element 11m yagi, I know people who do the same with 3 and 4 element yagis, are they portable or not? Certainly not backpack postable!

If I want single element performance I can do that with my car, my bicycle or my backpack. I often drive my car with a 13' antenna attached, so I'm not worried about driving with big antennas, I've also spent a king's ransom on what is possibly the best mobile antenna money can buy, I've modified my car's tailgate to take the weight and forces associated with installing such an antenna, I'm not afraid of a little effort to maximise results, plus I like to make shit, it's something to do and I can learn from it

The thrill of making it through a pile up, to a station the other side of the World, with minimalist equipment is fantastic, see for yourself:


80W, 1/4WL antenna and romped through an EU pile up to Australia long path, some 14,232 miles between us :w00t:
https://www.youtube.com/watch?v=9R5UDAnXFLA

 

[Marconi]

The video is good work 35.

 

[ghutch]

Good looking rig....should be great for a field day outing or beach Dx weekend. Google "vertical Learnings" has a design very similar. Two element vertical for use on saltwater. I operate mobile about 99% so a good beach antenna gets my attention I live very near saltwater....operate off Ward Island here in south Texas many days....setting up right at the water.
Another antenna design I've looked at with ?? a 2 element moxon design for saltwater. Google M1PAF 20 meter vertical moxon.....could be setup for 10 easy.
One thing I have experimented with is a 3 element skypper horizontal beam...it has very good rejection but very little gain real world over a 5/8 wave vertical. Both were on saltwater but the skypper was only at 20 feet so my results may have been somewhat off...but for portable two element vertical is the bomb on saltwater..
A two element vertical dipole setup on saltwater shows about the same Dx gain as a 4-5 element yagi....I said Dx angle for those that might argue the pattern. I'm looking for the low angles. Keep us informed 35 this is the reason I hang around here.....good info! 73

 

[Henry HPSD]

Perhaps comparing them with ...

VDA (vertical dipole array)

OZ1CX VDA - Vertical dipole array
F4BKV Web Site

You could consider the Bi-square:
Saturn “Bi Square” | CB Antennas

Or a bobtail curtain or a Hentenna...

Most certainly fun testing with portable antenna's !


Kind regards,

Henry

 

[northern35s]

Perhaps comparing them with ...

VDA (vertical dipole array)

OZ1CX VDA - Vertical dipole array
F4BKV Web Site

You could consider the Bi-square:
Saturn “Bi Square” | CB Antennas

Or a bobtail curtain or a Hentenna...

Most certainly fun testing with portable antenna's !


Kind regards,

Henry

Hi Henry, thanks for the comments.

I've read F4BKV detailed website and the 6Y2A write up and the 'Team Vertical' story, all great information and freely provided, the internet at it's best.

One thing I don't think I mentioned in my original post was my interest/fascination with the simplicity of the coax dipole, I originally intended making a portable version of that for my backpack, but then started thinking about adding gain. Of course this increases complexity of any portable system, so I mulled over the implications and obstacles for about a year before I decided to say what the heck, stop wasting time and just get on with it

 

[northern35s]

Good looking rig....should be great for a field day outing or beach Dx weekend. Google "vertical Learnings" has a design very similar. Two element vertical for use on saltwater. I operate mobile about 99% so a good beach antenna gets my attention I live very near saltwater....operate off Ward Island here in south Texas many days....setting up right at the water.
Another antenna design I've looked at with ?? a 2 element moxon design for saltwater. Google M1PAF 20 meter vertical moxon.....could be setup for 10 easy.
One thing I have experimented with is a 3 element skypper horizontal beam...it has very good rejection but very little gain real world over a 5/8 wave vertical. Both were on saltwater but the skypper was only at 20 feet so my results may have been somewhat off...but for portable two element vertical is the bomb on saltwater..
A two element vertical dipole setup on saltwater shows about the same Dx gain as a 4-5 element yagi....I said Dx angle for those that might argue the pattern. I'm looking for the low angles. Keep us informed 35 this is the reason I hang around here.....good info! 73

Hi ghutch, thanks for the comments.

I've read all there is to read on 'vertical learnings' website, it's part of my inspiration

I'm exclusively mobile and have been for the last couple of years. I turned my shack into a mini gym with the intention of using a small bedroom in the house for the shack, well Mrs northern35s doesn't see it from my perspective, and I've yet to install my 65' tower that's been lying in the garden for way too long.

I've worked around 230 DXCC from the car / on foot, so it hasn't been a real burden being mobile, in fact the word 'mobile' at the end of my callsign is often worth 6dB
I was working overseas for 6 months during the Winter and came back at the end of April, so far this month I've worked 110 DXCC alone (I have a yearly DXCC running total), however they are slowing down rapidly now :sad: as conditions have been a little poor in the last week or two, but all is not lost, I had set myself a goal of 100 for the month and beat it with ease.

This forum is indeed good, plenty of people sharing their ideas and experience about I subject that I find fascinating

 

[jazzsinger]

Just a thought:

3 10m Fibreglass Masts

A long. (Depending on spacing you want for elements hinged halfway 2x2 or bigger, 3 holes drilled in it to accept masts,

Add a T2LT Driven to centre mast and 2 other masts with a wire refector on one and director on the other.

2 circular block's one wiith spikes for bottom and one with countersunk bolts sticking up you can attach 2x2 too, if top block is rotatable you can sink it in the shallows, and even turn it by hand.

3 ele directional beam just above water with ability to change direction, you already have most of the parts and portable as fuck

 

[northern35s]

Just a thought:

3 10m Fibreglass Masts

A long. (Depending on spacing you want for elements hinged halfway 2x2 or bigger, 3 holes drilled in it to accept masts,

Add a T2LT Driven to centre mast and 2 other masts with a wire refector on one and director on the other.

2 circular block's one wiith spikes for bottom and one with countersunk bolts sticking up you can attach 2x2 too, if top block is rotatable you can sink it in the shallows, and even turn it by hand.

3 ele directional beam just above water with ability to change direction, you already have most of the parts and portable as fuck

If I recall correctly, getting a good match to 50ohm was a problem with 3 elements, it would probably need a stub or other impedance transformer at the feedpoint.

 

[W5LZ]

Several ways to do that matching, pick the one easiest for you. And count on re-tuning every time you put it up. Ain't no 'step' for a 'stepper'...
- 'Doc

 

[Henry HPSD]

If I recall correctly, getting a good match to 50ohm was a problem with 3 elements, it would probably need a stub or other impedance transformer at the feedpoint.

It is possible to get a good match to 50 ohms...
3,00 M 3el OWA 7,04 dBi | CB Antennas

However, you can often have "more"
(fb/fr and gain) using less boom length.

Example:
1,74 M 3el F-yagi | CB Antennas

The last one is only a 12,5 ohm impedance antenne, though the folded dipole makes it "look" 50

Kind regards,

H.

 

[northern35s]

It is possible to get a good match to 50 ohms...
3,00 M 3el OWA 7,04 dBi | CB Antennas

However, you can often have "more"
(fb/fr and gain) using less boom length.

Example:
1,74 M 3el F-yagi | CB Antennas

The last one is only a 12,5 ohm impedance antenne, though the folded dipole makes it "look" 50

Kind regards,

H.

Hi Henry, thanks for the info.

I think I know where I went wrong with the 3 element I tried, I've just modelled another version using OWA dimensions, rather than stock design, bingo

There is just one however, I'm struggling to get worthwhile better forward gain, I'm stuck around 10.7dBi fwd, around 1dB greater than a two element version, which is probably right, I'm going to need 4 elements to see 3dB.
F/B isn't a big concern really, I'll have around 13dB with two elements and that makes an appreciable difference to noise as it is. When the weather picks up I might take the two element out to the waters edge and see what happens, cheers.

 

[vkrules]

Here is a few pics of my 2el with v reflector .

 

[vkrules]

I have to say . All my glass pier poles are in use so I suspended this one from a makeshift mount. The elements are 2.1 meters apart at the apex and 50 cm at the tips .The choke is 16 turns on 65 m former( siros gainmaster specs) . I get about 2 s points front to back . Yagi cad tells me about 10 db front to back and about 5.8 db gain. You can see it could be made rotatable on 1 mast. Check out the bandwidth and feedpoint impedance.