steel mesh for mobile 2/70 antenna?

[mjac]

I do not have a after market roof rack or basket on my T4R, nor do I wish to get one, but I do have factory rails with (alum) crossbars. I am wondering if mounting square of steel mesh to the crossbars would provide a sufficient antenna ground plane? The steel mesh I have available is what is commonly used on utility trailer loading ramps, appox 3/4" mesh?

The mesh would be appox 30" sq. with a hole (probably reinforced) centered to accommodate antenna mounting.

I haven't found much about 2 meter dual band ground plane requirements elsewhere except for the use of mobile mag antennas in homes, apartments, condos in combo with cookie sheets or tops of filing cabinets. One instance noted screwing a cookie sheet to the ceiling and inverting the mag antenna, but I digress.

I would like to stay away from a mag mount and go with something more robust/permanent without drilling a hole in the roof. I should add that I once had a nmo hatch mount but it did not survive the strain of a Larson 2/70 51" antenna

What say ye?

 

[Frdmskr]

Why not drill a hole? Best mount is an NMO properly installed. Second best would be an NMO mount that clamps on the hood or tailgate. Run the wire to the rig and enjoy!

See K0BG.com for info, pictures and ideas.


Sent from my iPhone using Tapatalk

 

[DaveInDenver]

KT4NR is right, an NMO in sheet metal is basically ideal.

But an artificial ground counterpoise under VHF antennas is not unusual. Anything fiberglass may use them, boats, RVs, Jeep hard tops, truck camper shells, etc. For 2m a 19" disk, square, radials would work, solid sheet, relatively tight mesh, copper foil, a few pieces of rod or wire, etc.

Conceptually similar to this:

 

[Hilldweller]

A small mount with radii like Dave is displaying will work for you, Mike. I did it on one of my motorcycles years ago for the CB and it worked very very well.
Or just buy a mount for the hood and use a ducky like I have on the Jeep. Sometimes we, as overlanders, overthink things...

 

[mjac]

Sometimes we, as overlanders, overthink things...

Ain't that the truth.

In spite of the hatch/hood mount I once had self destructing, I'll probably try another. Maybe the Diamond K400 I have looked at will be up to the task. I'll try a ducky too and keep the longer Larson for on road duty as appropriate.

All that remains is to decide where to put the new arrangement, back on the rear hatch as was the first trial or on the hood.

Thanks guys, for your help, both on and off list.

Mike

 

[Hilldweller]

You going to have it set up for next month when we camp?

I had a qso with N4AOW from Jay's property in November ---- 50 miles as the crow flies. That's with my 18" ducky on my horrible groundplane Jeep, hilltop to fire tower, my 65 watts to whatever John was pushing through the air at the time. ...he has an awesome set-up...

I like the ducky because it's hard to kill. That's more important to me than qrp or doing anything amazing with the radio. For trail coms and occasional dx, it's a fun hobby. If I feel like really playing, Tennmogger is usually around with his HF radios and we'll loft an antenna into a tree.

 

[mjac]

You going to have it set up for next month when we camp?

Unfortunately, no. I am currently in Florida visiting my wife's extended family. I can't do much T4R/Ham wise except to scheme and overthink the project. CB and FRS will be my only comms at CFW.

See ya late Fri night Jan 13. Bella, the 10 wk old Lab/Shepard and I, will try not to wake you. Looking forward to checking out as many rigs as I can on Sat, should be fun.

Mike

 

[PhulesAU]

One like this http://www.ebay.com/itm/TRAM-1246-N...58-PL-259-WX-CAP-Sold-by-W5SWL-/371492353928?

Or this http://www.ebay.com/itm/NMO-3-4-HOL...hash=item4af5b42f37:m:mQKLJ46gqOPjziP7E-bfE3g

I'd do this before trying to rig a ground plane. Just a thought.

 

[Hilldweller]

Unfortunately, no. I am currently in Florida visiting my wife's extended family. I can't do much T4R/Ham wise except to scheme and overthink the project. CB and FRS will be my only comms at CFW.

See ya late Fri night Jan 13. Bella, the 10 wk old Lab/Shepard and I, will try not to wake you. Looking forward to checking out as many rigs as I can on Sat, should be fun.

Mike

Oh well.

Make sure to meet Bob (Tennmogger) then and check out his mobile HAM shack. He'll probably be in a big camo LMTV. He'll be able to give you decades of Homer advice on what works, what's cheap, what lasts, etc.
I'm using a K/C light mount for my antenna, btw. I just drilled out the hole to fit the nmo.

 

[mjac]

Oh well.

Make sure to meet Bob (Tennmogger) then and check out his mobile HAM shack. He'll probably be in a big camo LMTV. He'll be able to give you decades of Homer advice on what works, what's cheap, what lasts, etc.
I'm using a K/C light mount for my antenna, btw. I just drilled out the hole to fit the nmo.

Thanks Bill, for the heads up re: Bob aka Tennmogger. I'll tell him you sent me I noticed in another thread, Thanksgiving camping?, he lives near me? Well, maybe a county or two away.

CBI seems to be the only ditch light bracket builder for a T4R. It attaches to the hood hinge but the user had to then either cut the vent plastic or heat gun the plastic and then close the hood down on the plastic a couple of times. I am not trilled with that approach. I have not been able to find out if there is enough metal to drill out to NMO either.

Mike

 

[Hilldweller]

Thanks Bill, for the heads up re: Bob aka Tennmogger. I'll tell him you sent me I noticed in another thread, Thanksgiving camping?, he lives near me? Well, maybe a county or two away.

CBI seems to be the only ditch light bracket builder for a T4R. It attaches to the hood hinge but the user had to then either cut the vent plastic or heat gun the plastic and then close the hood down on the plastic a couple of times. I am not trilled with that approach. I have not been able to find out if there is enough metal to drill out to NMO either.

Mike

Did you go on IH8MUD and ask around about mounts?

Bob's farm is on your side of Maryville and he's got lots and lots of radios. He's been a HAM since before I was born and loves to talk about the hobby/art. I'm sure we'll be on 20 and 40 meter a bit. Kos will be there too and has a multiband in his Grand Cherokee. We'll have other HAMs there too but I'm not sure about their equipment.
Jay's hilltops are high enough that you can simplex 100 miles sometimes on 2M. It's really a great location to play radios.

 

[sonoronos]

It's probably best to use an antenna analyzer and a reflected power meter.

There is no conceivable way that anyone on the internet can remotely evaluate your antenna!

You could spend all the money in the world on random antenna bits because the internet told you to, but with an antenna analyzer, you could build a two meter antenna out of rusty fence wire. buy one!!

That said, the reason why you haven't seen much about ground plane requirements for any antenna is because there isn't one. There's no universal equation. If you're mounting a vertical antenna on a vehicle, you may not be far enough from the ground to experience strong issues in impedance or reflectance due a lack of a ground plane. (proper or not.)

But in the end, you can't tell evaluate the difference between a pie tin, a wire mesh, or radial counterpoise - or whether or not you even "need" a ground plane without the proper equipment.

 

[Hilldweller]

It's probably best to use an antenna analyzer and a reflected power meter.

There is no conceivable way that anyone on the internet can remotely evaluate your antenna!

You could spend all the money in the world on random antenna bits because the internet told you to, but with an antenna analyzer, you could build a two meter antenna out of rusty fence wire. buy one!!

That said, the reason why you haven't seen much about ground plane requirements for any antenna is because there isn't one. There's no universal equation. If you're mounting a vertical antenna on a vehicle, you may not be far enough from the ground to experience strong issues in impedance or reflectance due a lack of a ground plane. (proper or not.)

But in the end, you can't tell evaluate the difference between a pie tin, a wire mesh, or radial counterpoise - or whether or not you even "need" a ground plane without the proper equipment.

If he had his antenna mounted I could evaluate it with one of these: http://www.keysight.com/main/campai...9912a&ef_id=WGEwyQAAAZfSHkJs:20161226150129:s
My RF engineers are moving out of my building to their new downtown offices at the end of January. I've worked with them for almost 10 years ----- free use of top tier meters....
I'll miss them for sure.

 

[DaveInDenver]

I've worked in aerospace RF and haven't had the chance to work with anything as cool as a 50GHz meter. Nice. My experience has only been up to 26GHz.

 

[Hilldweller]

I've worked in aerospace RF and haven't had the chance to work with anything as cool as a 50GHz meter. Nice. My experience has only been up to 26GHz.

Drool on this then. When my AEs get a new meter or a new meter is introduced, they ask me to light up a radio to test so they can become familiar with the device. We've scoped and probed everything on my Jeep.
Some of the meters cost more than my first two houses.
It's really fun working with Keysight. Look through their catalog and dream...