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1/4 wave vs. 5/8 wave

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MB

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It all depends on your location and where the signals are comming from among other things.

Generally speaking, a 1/4 wave 0dBd gain antenna radiates and receives more energy higher in the vertical plane to reach radio communication sites located in higher places. Therefore they are more useful in mountainous and metropolitan areas with tall buildings. A 5/8 wave 3dBd antenna radiates and receives more energy toward the horizon. Therefore they are best used in the flatlands and suburban areas.

You would think a 5/8 wave antenna would be better because of its 3dBd gain, but the 1/4 wave has really surprised me at times. I have both and sometimes the 1/4 will pick up things the 5/8 will not and vice/versa.

The best thing to do is to get a NMO mount and buy a 1/4 wave and 5/8 wave and try them both and find out for yourself.
 

hsdtech

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A 5/8 wave WILL give you better performance than a 1/4 wave, period. Compare the 2 antennas on a local repeater listening to the input frequency of the repeater when someone is transmitting. You will definitely hear the difference.


-Bill
 

djeplett

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hsdtech said:
A 5/8 wave WILL give you better performance than a 1/4 wave, period.
-Bill
I have to disagree with you and repeat what MB said and this is from experience: it will depend on the terrain. If you use a 5/8 and you need to hit a repeater that is higher in altitude than you there are times that you will not be able to get into it where a 1/4 wave will get you into it just fine. So to say it will give you "better performance period" is too strong a statement for me to agree with.
 

hsdtech

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djeplett said:
If you use a 5/8 and you need to hit a repeater that is higher in altitude than you.

Hmmm...I would think 99.999% of the time the repeater will be higher. LOL.
 

jhooten

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hsdtech said:
Hmmm...I would think 99.999% of the time the repeater will be higher. LOL.

It is not so much how high the repeater is on the tower as it is angle from your antenna to the repeater antenna. Anything over about 45 degrees the 1/4 will give you better signals than the 5/8. Over 60 degrees signals will be much better with the 1/4.

MB has it exactly correct.
 

grem467

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hsdtech said:
A 5/8 wave WILL give you better performance than a 1/4 wave, period. Compare the 2 antennas on a local repeater listening to the input frequency of the repeater when someone is transmitting. You will definitely hear the difference.


-Bill
i have to disagree with this statement as well. I switched to a 1/4 wave antenna and had a noticeable improvement on local repeaters, but the signals into repeaters 40 miles away did diminish.

it ALL depends on your usage and desired radation pattern.
 

NeFire242

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Radio service is subject to limitations, particularly near boundaries and in remote areas, and may vary based on system availability and capacity, equipment, terrain, signal strength, radio site availability, topography, weather, buildings, and other conditions, which may vary significantly.

Line of sight.

No one antenna will do it all.

When you're out and about try and look at what everyone else seems to be running the most. A 1/4 wave would like less noticable on your vehicle than a 5/8 so that might be something for you to consider if you don't want a vast amount of antennas on your vehicle or to stand out too much.
 

hsdtech

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Well IMHO,

I have used a 1/4 wave mobile antenna for 2m for about a year and now am currently using a 5/8 wave mobile.
The 5/8 antenna Receives and Transmits much, much better. By the way the 1/4 was a Diamond, and the current antenna is a cheaper brand.
I can now hear more repeaters AND transmit into them where I couldn't even hear them with the 1/4.
So Andrew, it seems that some people just want to argue the fact over real world performance vs. theory of a unity gain 1/4 wave (no gain) compared to a 3db gain 5/8 wave. Yeah it's taller, but mine is black like my truck so it's hard to see.
Remember, there is theory and then there is fact.

Good luck with whatever antenna you choose.


-Bill
 
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hsdtech

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jhooten,


Do you want me to pull out my ARRL Antenna Book too? There are TONS of questions I could ask you on the subject of antenna gain that I could get from a BOOK.

Re-read the original post. Which one will give me BETTER RECEPTION? Simple. The 5/8 wave antenna.


jhooten,

Question for you. Don't you have anything better to do than argue antenna theory? Seems to me that your first post came right out of a BOOK. But that is just MY opinion.
 
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jhooten

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I have not yet began to argue. Ther is a difference between an argument and a discussion.

Why is it so hard for you to accept that there is no one size fits all solution to the question?

BTW, books and a little over 30 years hands on experiance in the installation, operation, and maintneance of radio equipment from longwave through microwave.

The answers to the OP's questions are:
Difference: lenght of the radiating element and the resultant pattern produced.
Better: Depends on the conditions and evironment where you operate.

The OP list his location as the Bay Area of CA. This is a large metro area with many high rise buildings and mountains all around. It is possible he may be in an area under the repeater antenna. A 5/8 wave antenna with its compressed radiation pattern shooting rf out to the the horizon, with little signal going up, may not be the best choice in the concrete valleys of such an area. A 1/4 wave with a fuller radiation pattern, giving more vertical coverage will allow the signal to get to the overhead repeater.

You on the other hand, who have chosen not to list your location, may be better served by a 5/8 wave.

Me, I live in a rural county, near a larger city, on the edge of the coastal plain and a 5/8 is marginal into many of the repeaters. A 6dB colinear is much better. As I said it all depends on conditions and environment.
 

loumaag

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I will agree that there is a difference between discussion and argument, that said, let me throw a few generalized statements in here.

In relation to the general performance levels between 1/4 wave unity antennas and 5/8 wave gain antennas (or even higher gain collinear) it is a good general rule that the higher the gain the better the antenna will perform. Yes, there are situations where a unity gain antenna may perform better than a gain antenna, especially a gain antenna that alters the radiation pattern to achieve some of that gain.

To go along with that general comment, let me talk from some personal experience. When living in South Louisiana among the trees and over the swamps (read interference but a hell of a ground) I found that a 5/8 wave single band antenna worked better than a 1/4 wave for most applications while mobile. When using a multi-band antenna (collinear over 5/8) I was less happy but it still did better than a unity gain on either UHF/VHF. This result was not duplicated with a base antenna mounted at 30 feet. Indeed the best antenna I ever used over that wet ground was the RS VHF/UHF scanner antenna as a base antenna. It had no trouble accessing stations (simplex) out to 35 or 40 miles and repeaters at 90 miles (no amplifiers used). I did not get those results using a couple of different popular base gain antennas.

All of that said, was my results the same (mobile) when I lived in South Dakota (the flat east side)? No, I never figured out what worked best, but my experience did tell me I was not getting the same performance that I had in S. Louisiana. I should have spent more time at Burghardts. ;)

Now back to a general comment...well not so much of a comment as a concern. This thread was heated enough to attract a report to the moderators. It seems that it is not so bad, but lets try and keep it civil. :cool:
 

hsdtech

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jhooten,

Of course I know there isn't one single "best" antenna, for ANY application. But he is asking about the best RECEPTION of 1/4 and 5/8 wave antennas.

You keep talking about TRANSMITTING. I'm sure you know there is a difference.

Why is it so hard for YOU to accept that in HIS application for a RECEIVING vertical mobile antenna, the 5/8 wave IS better?

I live in a suburb of Baton Rouge. Mainly flat, lots of trees. Of course a 6db COLINEAR would be best, but this is a 3RD antenna, and a base antenna at that which I also have. I have LOTS of antennas, BUT this post is from an EMT, asking about a 1/4 and a 5/8 wave, which I am 99% sure he is talking about MOBILE antennas.

To answer the original post, for MOBILE RECEPTION the 5/8 wave antenna would be the best.

Posts like these ALWAYS seem to get off topic.
 

NeFire242

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What about running (transmit & receive) a 1/4 wave vs. a 5/8 wave, and driving down the interstate at 60mph, do you believe the 5/8 wave antenna moves enough with that much wind to shift your pattern to where it would not be nearly as effect even though it has the 3dB of gain?
 
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hsdtech said:
A 5/8 wave WILL give you better performance than a 1/4 wave, period. Compare the 2 antennas on a local repeater listening to the input frequency of the repeater when someone is transmitting. You will definitely hear the difference.


-Bill
sometimes i notice the difference sometimes not. I have a mobile 2m/70cm dualband 1/4 wave and a mobile 160mhz 5/8 wave and sometimes i can't tell the difference when train scanning and using hot box detectors as a test signal. i'm in the flint hills in KS btw.
 
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kb2vxa

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Hi jhooten and all,

"Question for you, where in the antenna does the gain come from?"

Have you noticed that after sifting through all the BS nobody answered your question? SIMPLY stated it doesn't come from in the antenna but from the antenna. (;->) OK, that was TOO simple, so it comes from the radiation pattern. To start, "isotropic" represents the perfect omnidirectional radiator, that is it radiates equally well in all directions, a perfect sphere. There just ain't no such animal but in any case this mathematical model is used as a reference, zero dB gain.

Next is the real world antenna reference, the dipole (vertical) or groundplane that radiates a horizontal doughnut pattern, equally well in all directions but mostly in a horizontal plane. Now a doughnut has vertical angles as well so some of the energy radiates skyward and into the ground where it is reflected skyward, just a bit of a waste when you're shooting for the horizon.

Enter the dragon, er, the 5/8 wave with a somewhat flatter doughnut. More energy to the horizon and less skyward gives greater range over flat terrain. Now along comes an elephant to sit on the doughnut flattening the heck out of it, the colinear antenna is born. Live birth I suppose, even our mutant elephant doesn't lay eggs. (Some people who don't understand basic theory do but that's another matter, see my tag line below.)

Along comes the directional beam, the Yagi being the most popular. Now we're squishing the doughnut from the rear and sides so the jelly squirts in one direction spraying the mountain range in the far distance. Bigfoot is mad as hell, jelly makes a mess of his fur no matter how good it tastes. Phooey on Bigfoot, the point is you have to squeeze the doughnut to squirt the jelly, the signal goes farther than when you don't.

Now to settle the "arguement" about repeaters, northern NJ is mountainous while central and southern is flat so hams up north prefer 1/4 wave mobile antennas while others prefer 5/8 wave to accomplish the same thing in different environments. Take the "extreme engineering" involved to communicate with the ISS or Space Shuttle, hardly extreme at all. Many of us have done it loud and clear using 5W into groundplanes and the only "dead spot" is directly overhead. On the other hand those with gain antennas can only get it when it's low on the horizon, it's that elephant and doughnut trick again. Never mind the big boys with the satellite tracking antennas and computers, anyone can bounce a signal off the moon if you have enough money. I talked to the astronauts on my HT and a groundplane I cobbled together in 5 minutes using an SO-239 and some 12ga wire, ha ha.

Now what was that stuff about the ARRL's Radio Amateur Handbook? You won't find elephants and doughnuts in there, they don't think an elephant with a sticky behind is funny I suppose. You won't find them in the Antenna Handbook either but I once saw a pigeon skeleton hanging on the radial of a CB antenna, must have been the jelly doughnut he was after.
 

Josh

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My experience with VHF is that both antennas have appeared to work equally.

I choose a 1/4 wave over 5/8 wave not only because of size, but when you're travelling down the freeway, or other road above 45mph, the 5/8 wave bends far too much and received signal degrades significantly. Luckily, a 5/8 wave UHF antenna is about the same length as a VHF 1/4 wave, which is short enough to stay more rigid at higher speeds.

-Josh
 

k9rzz

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grem467 said:
i have to disagree with this statement as well. I switched to a 1/4 wave antenna and had a noticeable improvement on local repeaters, but the signals into repeaters 40 miles away did diminish.

it ALL depends on your usage and desired radation pattern.
You could stick your finger in the antenna socket and get good reception on a lot of local repeaters.

In general, for overall performance, I'd chose a 5/8 wave over a 1/4 wave.

The problem in my mobile is driving through the parking structure at work .... !BANG! .... !BANG! .... !BANG! .... (gee, maybe that 1/4 wave is good enough). :^]

John K9RZZ
 

OpSec

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Josh said:
My experience with VHF is that both antennas have appeared to work equally.

I choose a 1/4 wave over 5/8 wave not only because of size, but when you're travelling down the freeway, or other road above 45mph, the 5/8 wave bends far too much and received signal degrades significantly.
-Josh
That is a broad statement to make.

I've run a mix of VHF antennas from the el cheapo Valor magmounts (in my early days of mobile ham radio) to commercial equipment with NMO mounts (current day), and I've never noticed a "significant" degradation of VHF signals at Interstate speeds with any 5/8 wave antenna I've had installed...mag mount, trunk lip or NMO.

It's been my experience that so-called "picket fencing" occurs more with a 1/4 wave than a 5/8 wave at Interstate speeds, when gauging signal strength with a known transmitter like the local NOAA NWR transmitters.
 
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