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75 meter hamstick vs low dipole
If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
75 meter hamstick vs low dipole
Buck wrote:
If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? The low dipole is probably much more efficient than the hamstick and most of the radiation is straight up which is not necessarily a bad thing on 75m. Your question reminds me of one on a clinical psychological test. "Would you rather take one or two days to die an agonizing death?" :-) -- 73, Cecil http://www.w5dxp.com |
75 meter hamstick vs low dipole
On May 1, 2:49 pm, Buck wrote:
If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? No. |
75 meter hamstick vs low dipole
Christopher Cox wrote:
Cecil Moore wrote: Buck wrote: If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? The low dipole is probably much more efficient than the hamstick and most of the radiation is straight up which is not necessarily a bad thing on 75m. Your question reminds me of one on a clinical psychological test. "Would you rather take one or two days to die an agonizing death?" :-) I think the original post needs a couple of questions asked. Agreed the low lying dipole is ideal for a NVIS antenna. It would be interesting to see what kind of results would be had for contacts greater than 600 miles between the two antenna's. That Hamstick isn't going to be very efficient, so I guess it comes down to whether or not the reduced efficiency of the dipole at the desired DX angle allows for greater signal than the bad efficiency of the Hamstick at all angles... Suffice it to say that it probably isn't a very good option to run a Hamstick setup at home when there are any other options available. - 73 de Mike N3LI - |
75 meter hamstick vs low dipole
Michael Coslo wrote in
: Christopher Cox wrote: Cecil Moore wrote: Buck wrote: If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? The low dipole is probably much more efficient than the hamstick and most of the radiation is straight up which is not necessarily a bad thing on 75m. Your question reminds me of one on a clinical psychological test. "Would you rather take one or two days to die an agonizing death?" :-) I think the original post needs a couple of questions asked. Agreed the low lying dipole is ideal for a NVIS antenna. It would be interesting to see what kind of results would be had for contacts greater than 600 miles between the two antenna's. That Hamstick isn't going to be very efficient, so I guess it comes down to whether or not the reduced efficiency of the dipole at the desired DX angle allows for greater signal than the bad efficiency of the Hamstick at all angles... Suffice it to say that it probably isn't a very good option to run a Hamstick setup at home when there are any other options available. - 73 de Mike N3LI - Your not going to gain anything from the swap. I've compared a full size dipole to a hamstick dipole on 80m at the same hight. The dipole was 20db (about 3 S-units) better than the hamsticks. You will not gain anything close to 20db by putting the hamstick dipole up higer. On 40m a hamstick dipole is only about 10db worse than a full size dipole, better still on the higher bands. And yes I'm talking about hamstick dipoles using the right models for each band. On 80m the 2:1 SWR bandwidth is about 60KHz, wider on 40m but still narrower than a dipole on all bands. Ham stick dipoles seems attractive, but they fall into the better than nothing class on the lower bands. John Passaneau |
75 meter hamstick vs low dipole
On Fri, 2 May 2008 13:27:58 +0000 (UTC), John Passaneau
wrote: Michael Coslo wrote in : Christopher Cox wrote: Cecil Moore wrote: Buck wrote: If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? John, The idea I have is to make a vertical ground plane with the HamStick. Ham stick dipoles seems attractive, but they fall into the better than nothing class on the lower bands. John Passaneau i fully understand that the HamStick is not a great antenna fro that band, but how would the vertical ground plane made of a HamStick and two full length radials compare to a dipole at the same 10 foot level? what would the angle of radiation be like? -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
75 meter hamstick vs low dipole
Buck wrote:
what would the angle of radiation be like? Probably about 25 degrees with -20dBi gain. -- 73, Cecil http://www.w5dxp.com |
75 meter hamstick vs low dipole
Buck wrote in
: On Fri, 2 May 2008 13:27:58 +0000 (UTC), John Passaneau wrote: Michael Coslo wrote in : Christopher Cox wrote: Cecil Moore wrote: Buck wrote: If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? John, The idea I have is to make a vertical ground plane with the HamStick. Ham stick dipoles seems attractive, but they fall into the better than nothing class on the lower bands. John Passaneau i fully understand that the HamStick is not a great antenna fro that band, but how would the vertical ground plane made of a HamStick and two full length radials compare to a dipole at the same 10 foot level? what would the angle of radiation be like? My suggestion would be to download the trial version of EZNEC and model a 7’ wire over ground. That is an easy model to do and will tell you what the pattern will look like. As to the gain it will be just about the same as my tests, about 20db down from a full size antenna. The reason is hamsticks are very lossy on 80m and the bandwidth will still be about 60KHz. Anyway learning how to model antennas is a lot of fun and you can try out a lot of different antennas easly. I can say from experance that modeling works. Everything that I’ve carefuly modeled worked just like the model. John Passaneau |
75 meter hamstick vs low dipole
In article ,
Buck wrote: i fully understand that the HamStick is not a great antenna fro that band, but how would the vertical ground plane made of a HamStick and two full length radials compare to a dipole at the same 10 foot level? I think it would compare badly to the dipole. With the dipole, you'll have working in your favor the basic radiation resistance of a dipole in free space, reduced by the proximity of the dipole to the "reflector" (the lossy soil). Working against you, will be the losses in the soil. It'll certainly be a cloudwarmer... good for NVIS, not for DX as there will be little energy at a low radiation angle. If you short the dipole wires and use it as a two-wire sort-of- elevated radial set, the radiation resistance of these wires will be very close to zero - the far-field radiation from them will cancel out almost entirely. You'll still have substantial losses in the soil, I think, as the wires are only a small fraction of a wavelength above the soil surface. The radiation resistance of the HamStick itself is going to be quite low (an ohm or so??), and it certainly has a substantial amount of loss resistance. My SWAG is that by making this change, you might drop your radiation efficiency from 25% (low dipole over lossy ground) to 5% or less (lossy short vertical, over an inadequate radial network with substantial ground losses). Don't trust these numbers! what would the angle of radiation be like? Probably much like that of any other very-short monopole over a lossy ground... pretty much omnidirectional, with a modest null pointing straight up. It *may* have more low-angle radiation in the pattern than the low-dipole arrangement, but I think you'd lose most or all of the pattern advantage due to the lower radiation efficiency. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
75 meter hamstick vs low dipole
"Buck" wrote in message ... If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? Buck N4PGW -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." Assuming a 7 ft monopole, with a lumped element inductor (located in the middle of the vertical) of Q = 500, and 100 W input. The total radiated (sky wave) power is 1.4 W. The gain is -12.7 dbi with a take-off angle of 23 degrees. At resonance the input impedance is 14 ohms. 73, Frank |
75 meter hamstick vs low dipole
Frank's wrote:
Assuming a 7 ft monopole, with a lumped element inductor (located in the middle of the vertical) of Q = 500, and 100 W input. The total radiated (sky wave) power is 1.4 W. The gain is -12.7 dbi with a take-off angle of 23 degrees. At resonance the input impedance is 14 ohms. And the Q of a hamstick is probably a lot closer to 50 than to 500. Someone else reported the hamstick as -20 dBd. -- 73, Cecil http://www.w5dxp.com |
75 meter hamstick vs low dipole
And the Q of a hamstick is probably a lot closer to 50
than to 500. Someone else reported the hamstick as -20 dBd. I would think it would be hard to design a coil with a Q of 50. I tried to find a picture of a Hamstick to estimate the Q, but no luck. Anyway, assuming the Q is 50, NEC returns the following results: Structure efficiency - 5% Total radiated sky wave (with 100 W in) = 180 mW. Input impedance - 112 ohms. 73, Frank |
75 meter hamstick vs low dipole
Structure efficiency - 5% Total radiated sky wave (with 100 W in) = 180 mW. Input impedance - 112 ohms. PS -- and the gain is -23 dbi at a 20 deg TOA. |
75 meter hamstick vs low dipole
Frank's wrote:
PS -- and the gain is -23 dbi at a 20 deg TOA. Someone measured it at -20dBd so that may be fairly accurate. -- 73, Cecil http://www.w5dxp.com |
75 meter hamstick vs low dipole
On Thu, 01 May 2008 15:49:00 -0400, Buck
wrote: If I have a low dipole about 10 feet off the ground for 75 meters, would it be better if I put a hamstick 75 meter vertical up and connect the dipole wires to the ground side for a vertical? Buck N4PGW In another forum, I was informed that the signal for the vertical was very low at every angle compared to the dipole. One of the things i was thinking about was if it would be beneficial to add a good ground radial to the mobile whip on the car, once parked. however, it is obvious that if one can raise, even 10 feet, a full sized 1/2 wave dipole, it would produce much better results being left in the dipole configuration. Thank you to all who participated. (Even to the one who simply said "NO"). that was a short, sweet and to the point answer. :) 73 for now Buck n4pgw -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
75 meter hamstick vs low dipole
It just occurred to me that I have over looked something that might have
some use in this discussion. I just realized that this thread is about a low dipole compared to a vertical Hamstick antenna. I reported that I have compared a Hamstick dipole to a full size dipole and that it was down 20db from the full size dipole. I can also report on a Hamstick vertical compared to a full size dipole on 80m. For some years I’ve been using a phased vertical system as a receive antenna on the 80m SSB Dx window. It is 2 Hamstick’s spaced 1/16 wave apart and feed 90 degrees out of phase with a relay system that lets me switch directions. As a receive antenna it works very well. A friend that has a 900’plus beverage tells me that it compares very well. For me it gives me about at 15db signal to noise advantage over my transmit dipole. The front to back is also about 20db in the most favorite direction. But here is the part that is germane to this thread. The signal level compared to the dipole is still about 20db down. I don’t care as receivers have a lot of extra gain and the increase in signal to noise makes all the difference. I don’t have much of a ground system, just 4 10’ radials under each vertical but putting down a good ground will not make up 20db, no way. The main advantage that a beverage has over this antenna is that it will cover several ham bands and the Hamstick verticals are only good for about 100Khz around the DX window but that is all I want and it fits in my yard as the spacing is only about 30’. So I can say that a phased hamstick vertical on 80m with a poor ground is also about 20db down from a full size dipole at 40’. John, W3JXP |
75 meter hamstick vs low dipole
John Passaneau wrote:
So I can say that a phased hamstick vertical on 80m with a poor ground is also about 20db down from a full size dipole at 40’. It all makes good sense. The best 75m mobile antennas are about 10 dB down from a 1/2WL dipole. The hamstick is about 10 dB down from the best 75m mobile antennas. -- 73, Cecil http://www.w5dxp.com |
75 meter hamstick vs low dipole
On May 5, 10:19 am, Cecil Moore wrote:
John Passaneau wrote: So I can say that a phased hamstick vertical on 80m with a poor ground is also about 20db down from a full size dipole at 40’. It all makes good sense. The best 75m mobile antennas are about 10 dB down from a 1/2WL dipole. The hamstick is about 10 dB down from the best 75m mobile antennas. -- 73, Cecil http://www.w5dxp.com It's the lack of a decent radial system which makes me look at it in a negative manner.. It's quite possible for the short vertical to outplay the low dipole for DX, but... I don't see it happening with only 2 radials and low to the ground. The hamstick would actually work better mounted on a vehicle than it would in that 2 radial scenario I bet. So it's more the ground radial problem, rather than the short radiator itself. On 40m, my mobile outplays my 35-40 ft high dipole to DX. But, I don't know if that would be the case with two low radials, vs the usually better RF ground that my vehicles provide. With a low vertical on 80m, two radials ain't gonna get it done as far as avoiding ground loss. And the short vertical makes things even more critical. For NVIS use, the low dipole would *smoke* the short vertical with two radials. I've run low 80m dipoles 5-10 ft off the ground when camping, and still had fairly decent results to regional stations. MK |
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