Need some HF antenna advice what mobile HF antenna to get?
- Thread starter Nomad1
- Start date
unusedusername
Observer
Have you read http://www.k0bg.com/ ?
The short version: any band below 10 meters requires an antenna too long to mount on a vehicle. This means that mobile hf antennas all operate at negative gain, with worse performance the lower the band. The best you can hope for is about 9-10% efficiency on 40m (100w in, 10w out) and that's with an antenna too large to take offroad. Be prepared to ground everything or your vehicle electronics will freak out when you key up.
I personally use a small screwdriver (little Tarheel HP). The screwdriver gets 3-5x the efficiency of a hamstick, at 60x the price. It does work, but it's about the same experience as running QRP with a full sized antenna, except the radio is set for 100 watts. I can get my efficiency up higher by replacing the whip on my screwdriver with a long wire using Tarheel's QD whip mounts then using the coil on the screwdriver to tune the wire. It works, but don't forget to unhook it before driving away.
I've tried hamsticks also, and I found those to not really be worth my time. You can hear OK, but basically nobody is ever above a S3. The main problem is that nobody can hear you. The 80meter hamstick is less then 1% efficient, so 100 watts in and less then one watt is radiated.
You can do pretty well on 10 meters though. A quarter wave whip is ~8 feet long, and that works pretty well on the rare occasions when that band is open. My jeep makes a reasonable counterpoise for the whip, although it would probably work better if I rigged up ground radials. The whip is too long and whippy to take offroad though. I wouldn't want to hit my spotter with it. I removed it and replaced it with the aforementioned screwdriver.
The short version: any band below 10 meters requires an antenna too long to mount on a vehicle. This means that mobile hf antennas all operate at negative gain, with worse performance the lower the band. The best you can hope for is about 9-10% efficiency on 40m (100w in, 10w out) and that's with an antenna too large to take offroad. Be prepared to ground everything or your vehicle electronics will freak out when you key up.
I personally use a small screwdriver (little Tarheel HP). The screwdriver gets 3-5x the efficiency of a hamstick, at 60x the price. It does work, but it's about the same experience as running QRP with a full sized antenna, except the radio is set for 100 watts. I can get my efficiency up higher by replacing the whip on my screwdriver with a long wire using Tarheel's QD whip mounts then using the coil on the screwdriver to tune the wire. It works, but don't forget to unhook it before driving away.
I've tried hamsticks also, and I found those to not really be worth my time. You can hear OK, but basically nobody is ever above a S3. The main problem is that nobody can hear you. The 80meter hamstick is less then 1% efficient, so 100 watts in and less then one watt is radiated.
You can do pretty well on 10 meters though. A quarter wave whip is ~8 feet long, and that works pretty well on the rare occasions when that band is open. My jeep makes a reasonable counterpoise for the whip, although it would probably work better if I rigged up ground radials. The whip is too long and whippy to take offroad though. I wouldn't want to hit my spotter with it. I removed it and replaced it with the aforementioned screwdriver.
gary in ohio
Explorer
what bands do you want to operate. 10-20m a simple "hamstick" will work. 10-40m a good 12ft whip will work, for 10-80 a good screwdriver antenna is a must.
prerunner1982
Adventurer
Durability for off road a 102/108" whip and auto-tuner work, ok upto about 40m.
A big screwdriver antenna will probably work the best and give the most range of use, but I didn't want to have something so expensive and seemingly fragile hanging off my Jeep. I live in the country and my antennas hit trees every day. I didn't think it would last long.
I use hamsticks and have had decent success with them. I only got on HF a year ago so the solar cycle and propagation weren't great to begin with however I have talked all over the world mobile. My longest is New Zealand at about 8100 miles, had a nice conversation with Ed (ZL4IR). Of course being mobile, a lot of it depends on what antenna they are using too. Sure it's a pain to carry/change out the antennas but if one breaks I am out $16 and can still use the others.
I carry a 10m, 20m, and 40m hamstick so I have use of 6m, 10-12m, some of 15m, 20m, and 40m.
A big screwdriver antenna will probably work the best and give the most range of use, but I didn't want to have something so expensive and seemingly fragile hanging off my Jeep. I live in the country and my antennas hit trees every day. I didn't think it would last long.
I use hamsticks and have had decent success with them. I only got on HF a year ago so the solar cycle and propagation weren't great to begin with however I have talked all over the world mobile. My longest is New Zealand at about 8100 miles, had a nice conversation with Ed (ZL4IR). Of course being mobile, a lot of it depends on what antenna they are using too. Sure it's a pain to carry/change out the antennas but if one breaks I am out $16 and can still use the others.
I carry a 10m, 20m, and 40m hamstick so I have use of 6m, 10-12m, some of 15m, 20m, and 40m.
Hillbilly Heaven
Explorer
I am going to throw this little tidbit in the pile. Most screwdriver antennas get taller as the frequency goes down. This does present a problem with hitting low hanging objects. Options are to lower or remove it till you are parked or fold it over.
A few options can get around this.
First is a 102" whip and tuner. Easily folded over to clear objects Works good 10 thru 15 meters but loses efficiency the lower you go in frequency. Not likely damaged
If you a running an Icom radio they brought out with the 7100 radio an automatic HF antenna. This antenna has no external moving parts. All the tuning occurs automatically in the base of the antenna thru an interface with the radio. This antenna is very similar to Stealth Telecom's automatic HF antenna. Stealth Telecom no longer list this antenna so Icom may have bought the rights to it. Major downside is cost $1500 for the antenna + $140 for the interface cable. If you want to use the antenna for NVIS work then add another $1000 for a fiberglass whip and mount. Yes the antenna is broadband and convenient, but no more efficient than the 102" whip.
Hamsticks are good but as far as efficiency are no better than a typical screwdriver. Bandwidth is very limited. If you throw a tuner inline then you lose the efficiency but gain bandwidth. Very economical and semi rugged It is fiberglass and will break.
Last option I am familiar with that is highly recommended by others not because of price but because of efficiency and durability. Hi-Q antennas produces a series of screwdrive type antennas that do not change in length as frequency changes. They offer a ruggedized version that is designed for this type of purpose. One stipulation is that the coil must be mounted above any structure near by ie cab, body, or hood. Don't worry about hitting low hanging objects, the coil is designed to take it. You have your choice of whip lengths above the coil. If you choose you may fold over the whip as well, doing so will give you NVIS ops. They do offer a million mile offer of a new antenna when you reach one million miles of use. Cost compared to other screwdrive type antennas is more but you are paying ruggedness and increase efficiency over other screwdriver antennas.
Before you buy an antenna sit back and think where and when you plan on operating. Can you get by without an antenna till you get to where you are parked or do you want to be able to operate anywhere anytime? Do you want to work dx or are you more interested in working local out to 300 miles NVIS? Remember that you will not find a mobile antenna to match the efficiency of a 1/2 wave dipole. There is no magic bullet. Some are better than others. Some are nothing more than a bad dummy load. You have to decide what you are willing to trade off. Just remember rule #1 the more wire you can stick in the air in a straight line that offers a 50 ohm impedance without a tuner the more efficient and wider bandwidth it will have. This does not mean wrap a bunch of wire around a stick just so it matches all you did is create a base loaded antenna. Essentially all screwdriver and hamstick type antennas are base loaded whips. That is the reason for the difference in efficiency because the coils are designed differently.
A few options can get around this.
First is a 102" whip and tuner. Easily folded over to clear objects Works good 10 thru 15 meters but loses efficiency the lower you go in frequency. Not likely damaged
If you a running an Icom radio they brought out with the 7100 radio an automatic HF antenna. This antenna has no external moving parts. All the tuning occurs automatically in the base of the antenna thru an interface with the radio. This antenna is very similar to Stealth Telecom's automatic HF antenna. Stealth Telecom no longer list this antenna so Icom may have bought the rights to it. Major downside is cost $1500 for the antenna + $140 for the interface cable. If you want to use the antenna for NVIS work then add another $1000 for a fiberglass whip and mount. Yes the antenna is broadband and convenient, but no more efficient than the 102" whip.
Hamsticks are good but as far as efficiency are no better than a typical screwdriver. Bandwidth is very limited. If you throw a tuner inline then you lose the efficiency but gain bandwidth. Very economical and semi rugged It is fiberglass and will break.
Last option I am familiar with that is highly recommended by others not because of price but because of efficiency and durability. Hi-Q antennas produces a series of screwdrive type antennas that do not change in length as frequency changes. They offer a ruggedized version that is designed for this type of purpose. One stipulation is that the coil must be mounted above any structure near by ie cab, body, or hood. Don't worry about hitting low hanging objects, the coil is designed to take it. You have your choice of whip lengths above the coil. If you choose you may fold over the whip as well, doing so will give you NVIS ops. They do offer a million mile offer of a new antenna when you reach one million miles of use. Cost compared to other screwdrive type antennas is more but you are paying ruggedness and increase efficiency over other screwdriver antennas.
Before you buy an antenna sit back and think where and when you plan on operating. Can you get by without an antenna till you get to where you are parked or do you want to be able to operate anywhere anytime? Do you want to work dx or are you more interested in working local out to 300 miles NVIS? Remember that you will not find a mobile antenna to match the efficiency of a 1/2 wave dipole. There is no magic bullet. Some are better than others. Some are nothing more than a bad dummy load. You have to decide what you are willing to trade off. Just remember rule #1 the more wire you can stick in the air in a straight line that offers a 50 ohm impedance without a tuner the more efficient and wider bandwidth it will have. This does not mean wrap a bunch of wire around a stick just so it matches all you did is create a base loaded antenna. Essentially all screwdriver and hamstick type antennas are base loaded whips. That is the reason for the difference in efficiency because the coils are designed differently.
Hillbilly Heaven
Explorer
And if you are going to run 80 or 40 meters a shunt coil mounted at the base of the antenna helps.
Nomad1
Observer
Thanks for the link to k0bg.com
I think for now I am just going to setup a pole with dipole for 10 to 40 just to get started.
I am happy enough just to ham around when I am camping something to kill time in the evening am interested to see what kind of contacts can happen and want to see if I get any contacts when I do my trip up to Tuk.
This gives me a year to tweak or change the setup before the big trip.
I Like to DIY stuff I will keep looking around and see if I find something I like unless I can find something online for the right price.
If anyone has any other ideas for me to check out or try please post!
Nomad
I think for now I am just going to setup a pole with dipole for 10 to 40 just to get started.
I am happy enough just to ham around when I am camping something to kill time in the evening am interested to see what kind of contacts can happen and want to see if I get any contacts when I do my trip up to Tuk.
This gives me a year to tweak or change the setup before the big trip.
I Like to DIY stuff I will keep looking around and see if I find something I like unless I can find something online for the right price.
If anyone has any other ideas for me to check out or try please post!
Nomad
Last edited:
unusedusername
Observer
The "put up a pole with a full sized antenna" idea is a great one, as long as you don't need to use it while in motion. A full sized antenna will work much better then the best compact one.
I run a fridge in my offroad trailer, so I've got enough solar power for a few hours per day of mobile HF rig and tuner at 100w. I bring a off center fed dipole (this one) and a 18' aluminum telescoping mast and tripod (this one).
This image is me running a test of the equipment in a developed campground in Mesa AZ:
I run a fridge in my offroad trailer, so I've got enough solar power for a few hours per day of mobile HF rig and tuner at 100w. I bring a off center fed dipole (this one) and a 18' aluminum telescoping mast and tripod (this one).
This image is me running a test of the equipment in a developed campground in Mesa AZ:
Hillbilly Heaven
Explorer
Just remember most wire antennas mounted 30' high or less are going to be NVIS and will be limited to 300 miles distance or less. I haven't tried them and I don't know how well they would work erecting one for camping, but you might consider a ground independent vertical for DX. Keep in mind we are near the bottom of the solar cycle so the low bands are going to be the best choice but the most difficult in portable ops.
PhulesAU
Explorer
I run a 66' OCFD at 28" and have coverage around the planet. You need to check your facts.
I have had numerous hamsticks on my Sierra, a screwdriver and now have a variation to Alpha Moto. All were compromise antennas. I did have good luck with a 102"whip and tuner. For campsite I use a Miitary Ez antenna on a 8' painters pole with a MFJ 1979 (I think) stainless telescoping antenna. I find that works better than a dipole at low elevation.