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Author Topic: Vertical antenna comparisons  (Read 1805 times)
AF5CC
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« on: April 05, 2013, 07:04:33 PM »

How do the "radialless" verticals, like the R5, R7000, MA5V, Gap ones, compare in performance to the standard 1/4 wave verticals that are roof mounted with radials?  Does one tend to outperform the other?  I am looking how each performs for DXing and longer haul communications.

73 John AF5CC
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AC4RD
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« Reply #1 on: April 06, 2013, 06:41:45 AM »

John, I'm no expert, not at all.  I had a Gap Eagle a dozen years ago and it performed pretty well, all things considered, but a decent dipole usually worked better for DX.  The last couple of years I've played with a handful of homebrewed elevated verticals with radials, and those have been really good performers in general.  (Plus they've been a lot of fun to experiment with!)   

The Gap Eagle I had wasn't really a regular vertical, it was more of a vertical dipole.  It wasn't bad, but I think it was a bit of a compromise.   It might be a good choice if your space is limited and you're not interested in exotic DX.  My guess is a traditional vertical with radials might be a better fit for you, from what you said.  But again, I'm no expert. :-)  GL!  -ken
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N8NSN
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« Reply #2 on: April 06, 2013, 07:17:21 AM »

Hi John. Good question. Especially with the ever increasing dbi vs dbd numbers used to make the numbers appear larger - in attempts to promote sales. The dbd and dbi numbers are both variables, per installation. "Your milage may vary" is the only accurate phrase on an antenna.

Absolutely, the antennas you mentioned are workable antennas - properly installed. However, ALL shortenen, multi-band, trapped antennas are a compromise when compared to an, again - properly installed (and built): 1/4, 1/2, or 5/8 wavelength vertical antenna. Then we have the variables of feasability in whether to ground mount the vertical(s) or to elevate the feedpoint and radials.

My own personal experiance is that on the bands of primary use (40 & 80) home brew 1/4 wave, elevated radials (ground plane) antennas have served me best, both financially and performance wise. For bands of lesser interest (20 and up to 6 meters) the R-5 purchased used on the cheap served fine for 12 years - sold it... Still perfoms well for the new, third owner. Recently purchased an R-6000: again, used and on the cheap - LOVEIT! For a 20-6 (WARC inclusive) trapped / linear loaded - stubby radial (these short radials, by design only serve as common mode reducers) vertical... Tisthe fine antenna.

As with ANY antenna : efficiency, proper installation and feeding, and high Q in any components used in any base loading for proper feedline impedance matching are the main factors to consider.

One myth needing addressed is that ground mountedverticals require resonant ground wires. :FALSE... Unless it is a full length vertical 1/4 wave radiator. Then, yes - the ground wires need also be a 1/4 wave long.
However, loaded verticals - - when ground mounted - - need only between 16 and 120 grount wires - just slightly longer (2% maybe) than the PHYSICAL LENGTH of the vertical radiator. IOW, a loaded, in whatever form of loading, ground mounted, say for 80 through 10 meters, having a physical height of only 30 feet would only need the ground wires be roughly 36 feet long at the most...

Raise the same loaded vertical up andraise the counterpoise, though, and now full set of 2 per band resonant radials are required.

The manufactured, stubby radials, antennas mentioned, are 1/4 wave onlower bands and 1/2 wave radiators on the uppers. The "boxes at their bases" are matching networks to correct the associated impedance mismatches to the 50 ohm coaxial feeds. As stated earlier: the stubby radials reduce common mode.

Hope this helps. Best results for you, hoped for.
73
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VA2FSQ
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« Reply #3 on: April 06, 2013, 07:30:04 AM »

I've had the R6000 and replaced it with the Av620.  The R6000 uses traps and I was unable to get rid of it's shift of resonance when it rained.  The av620 uses stubs and is rock solid.  Both also generate a lot of rfi to neighbours electronics!

I've had good results with these antennas.  They are great for DX, in the last two weeks having worked Spratley, indonesia, China.  But conditions are a big factor. 

Both of these are very convenient.
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VA2FSQ
W9PMZ
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« Reply #4 on: April 07, 2013, 03:46:17 AM »

Radial less verticals work but with much less efficiency.

Over the years I have tried about every vertical, except the one I really want a 18HT.

Cost effective with radials the 5BTV wins hands down.

Multi band options with a little gain on higher bands the Butternut HF9 wins hands down.

73,

Carl - W9PMZ
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N0IU
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« Reply #5 on: April 07, 2013, 04:45:37 AM »

For 10-40 meters, I have been using a Cushcraft R7 for over 20 years. I have DXCC and WAS with band/mode endorsements on each.

Would I have earned these awards sooner with a "better" antenna? I guess we'll never find out!
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RFRY
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« Reply #6 on: April 07, 2013, 05:10:25 AM »

...However, loaded verticals - - when ground mounted - - need only between 16 and 120 ground wires - just slightly longer (2% maybe) than the PHYSICAL LENGTH of the vertical radiator. IOW, a loaded, in whatever form of loading, ground mounted, say for 80 through 10 meters, having a physical height of only 30 feet would only need the ground wires be roughly 36 feet long at the most.

Just to note that the wavelength of the radiation from a loaded, vertical radiator is the same as if that radiator was unloaded, and used on the same frequency.  It is the wavelength that is important to the length of buried radials, not the height of the vertical structure in use (whether or not it is loaded).  This link explains why  http://i62.photobucket.com/albums/h85/rfry-100/GroundCurrentNearMonopole.gif

The following link shows the amount of loss for different numbers and lengths of radials buried in typical earth, for monopoles with physical heights of 0-70 degrees http://i62.photobucket.com/albums/h85/rfry-100/GndSystemLosses_zps0b36c41e.jpg

The graphs show that for systems using a 54-degree vertical with 30 x 54-degree buried radials, about 45% of the power available from the transmitter is lost in the ground system.  For a 54-degree vertical with 120 x 54-degree buried radials, about 15% of the power available from the transmitter is lost in the ground system.

OTOH, A 54-degree vertical using 120 x 144-degree buried radials loses only about 2.5% of the power available from the transmitter in the ground system.

Base loading a short vertical radiator can reduce the reactance at its feedpoint to the point where the vertical+loading are naturally resonant, but that does not change the radiation resistance of that structure on that frequency.   It is the ratio of the radiation resistance to all of the ohmic losses in the antenna system that determines how much of the available power is radiated as EM energy, rather than lost as heat.

As loaded/unloaded verticals that are physically short in terms of wavelength have lower values of radiation resistance, it becomes more important to reduce the r-f loss in the set of buried radials in use.

These two links taken together illustrate the value of using numerous buried radial wire lengths significantly longer than the physical height of a short, vertical radiator (loaded, or not).

R. Fry
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WA3SKN
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« Reply #7 on: April 08, 2013, 03:22:36 PM »

Bandwidth!
The 1/4 wave vertical with full size 1/4 wave radials will have a greater bandwidth than if you shorten them up with coils.  When you shorten both, the bandwidth gets smaller still.  Both will resonate at the design frequency and have a low radiation angle, but the Q gets higher with the loaded design and the bandwidth suffers.
But if there is no room for those radials the loaded antenna will get you on the air!
73s.

-Mike.
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K8QV
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« Reply #8 on: April 08, 2013, 05:05:56 PM »

All I can tell you is my experience. My R-7 mounted at 14 ft. soundly outperformed every 1/4 wave vertical with radials, both the elevated and ground mounted versions, that I ever bought or built. I like DX so my rule is for 14 mHz and higher, a dipole at a decent height works better but lower frequency dipoles are too hard to get high enough so a 1/2 or 1/4 wave vertical works better than a dipole that's too low.
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NO9E
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« Reply #9 on: April 08, 2013, 06:55:18 PM »

I think it is location, location, location.

In clear places with high soil conductivity the vertical does very well. In places full of big trees/structures and with poor soil conductivity it does poorly.

No radial verticals may lose a few db  due to being short and gain a few due to being elevated.

My KX3/10W opened JA on 17m on a  beach in  FL. At my QTH in N Georgia. a full size vertical with 3 elevated radials does within 0.5 S of no-radial vertical (DX-77) but 2 S below a high dipole. DX included.

Ignacy, NO9E
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