I bought a rig master aa-35 zoom. I have a decent swr 1.6 but resistance is 30 ohms. I don’t know what that reading means. Like what is the issue. I had a cb shop put new coax in and supposedly ground the doors. I don’t see where they did that though. This is on a truck with dual antennas. I bought a antenna analyzer because I feel like I’ve been taken for a ride on this deal. I bought a new galaxy 66v2 that I’m not happy with from him. If I talk for any extended time my Reciever gets really quiet. Transmit side gets hot seemingly quick. Maybe the radio just isn’t capable of talking much I don’t know. I need to lear this stuff so I’m not throwing good money after bad.
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Help understanding my antenna analyzer
- Thread starter Magard
- Start date
I wouldn't run any radio with anything more than a 1.3 SWR. Your radio is looking for a 50 ohm load, and you're giving it a 30 ohm one. Pickup or big rig? Can we see some pics of the antenna install?
With the antenna system maybe it's not all fault of the Galaxy 66. I'd definitely address the antenna system first before even transmitting with that radio. First step I'd take is finding a reputable shop!
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50 ohms is the common impedance of antennas and radios.
The closer you get to 50 ohms, (52 is best) the better your match will be. It can take a couple different things to achieve that.
First, an antenna of good design. Typically, mobile antennas are 4 to 5ft in length which actually lowers the feed point impedance below 50 ohms being short of a 1/4 wavelength so a loading coil is used to bring up the impedance to near 50 ohms.
You probably just need to raise or lower the antenna whip(assuming it had one) to get a better match.
See your analyzers manual to learn how to sweep a band or range of frequencies so you can instantly see where the best match is. Then you know which way to adjust the antenna.
I use a Rigexpert analyzer and love it once you learn how to use it's many useful features.
Example pic below of my Rigexpert SWR plot. Target frequency was probably set for 7000 kHz (7 mHz) @ +/- 500 kHz bandwidth. The cursor at the bottom of screen can be moved to the lowest spot on the SWR curve revealing a frequency of 6.598 kHz where the cursor is. This is the lowest spot just below 1.2 SWR so to tune to 7000 kHz, the antenna needs to be shortened or lowered.
h
The lower the match is away from the target frequency, the shorter the antenna whip or the higher away from the target frequency, raise the antenna whip.
The target frequency is where you operate most. Make this the best match and let the antennas bandwidth cover the rest of the frequencies within it's range.
Ignore that CB shop way of tuning antennas that say match channels 40 and 1. What this does is gives you a balanced compromise tuning across the CB band.
Also to tune 2 antennas properly, you need to dummy load 1 side then tune the other then switch sides. Without a dummy load, your just guessing.
1 antenna works just fine and is far easier to setup. The co-phase gives you a more front to back pattern if mounted on mirrors or 2 sides of a vehicle whereas a single antenna centered on a vehicle (if possible )is omni-directional.
I say omni-directional is better for a mobile.
The closer you get to 50 ohms, (52 is best) the better your match will be. It can take a couple different things to achieve that.
First, an antenna of good design. Typically, mobile antennas are 4 to 5ft in length which actually lowers the feed point impedance below 50 ohms being short of a 1/4 wavelength so a loading coil is used to bring up the impedance to near 50 ohms.
You probably just need to raise or lower the antenna whip(assuming it had one) to get a better match.
See your analyzers manual to learn how to sweep a band or range of frequencies so you can instantly see where the best match is. Then you know which way to adjust the antenna.
I use a Rigexpert analyzer and love it once you learn how to use it's many useful features.
Example pic below of my Rigexpert SWR plot. Target frequency was probably set for 7000 kHz (7 mHz) @ +/- 500 kHz bandwidth. The cursor at the bottom of screen can be moved to the lowest spot on the SWR curve revealing a frequency of 6.598 kHz where the cursor is. This is the lowest spot just below 1.2 SWR so to tune to 7000 kHz, the antenna needs to be shortened or lowered.
hThe lower the match is away from the target frequency, the shorter the antenna whip or the higher away from the target frequency, raise the antenna whip.
The target frequency is where you operate most. Make this the best match and let the antennas bandwidth cover the rest of the frequencies within it's range.
Ignore that CB shop way of tuning antennas that say match channels 40 and 1. What this does is gives you a balanced compromise tuning across the CB band.
Also to tune 2 antennas properly, you need to dummy load 1 side then tune the other then switch sides. Without a dummy load, your just guessing.
1 antenna works just fine and is far easier to setup. The co-phase gives you a more front to back pattern if mounted on mirrors or 2 sides of a vehicle whereas a single antenna centered on a vehicle (if possible )is omni-directional.
I say omni-directional is better for a mobile.
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I did what you say and I have the swr as good as I could get. Out of adjustment on antenna. But the impedance is low. My question is what causes low impedance. Is it a ground problem?
You won't run a 1.3 vswr? Did you know driving down the road the antenna will flex and your swr will change quite a bit? 1.3 is good for all transceivers and most hams would be happy if the dipoles they run would get close to 1.3 anywhere in the band.
Yes, I did say I won't run anything higher than a 1.3 on my antenna systems. Are you trying to say I shouldn't bother tuning my antenna systems for max efficiency because "most hams" don't? Or that you're the first person to recognize that antennas can momentarily change in tune when they move or when it rains or snows on them? Most hams are appliance operators (I'm also a ham, I've met and talked to them) who rely on tuners or will run excessively high SWR because some book or manual told them it's perfectly fine. The OP is asking about the tune on a monoband (11 Meters) antenna system, not a multiband hambone antenna.
The true impedance of a quarter wave antenna, normally falls between 35-40 ohms.
What your looking for on the analyzer is this
Z=R or very close
X=0
This is where the antenna is truly resonant = greatest efficiency.
This normally occurs at about 1.4:1...1.5:1
When you tune the antenna for the "magic 1:1...you will normally see that X has a value Greater than 0...This is called reactance. Reactance (X) causes wasted power.
The trick on the analyzer is where is this point reached.
You need to measure the antenna on several channels.
Channel 1...better/worse
Channel 20...better/worse
Channel 40... better/worse
Looking at not only VSWR but X
If VSWR and X is lower on Ch:1 then then the antenna should be to long
If this occurs on Ch:40 then the antenna is too short
If you run the test in sweep mode as 4string suggested, the analyzer will tell you the point of resonance.
Hope this helps
All the Best
Gary
What your looking for on the analyzer is this
Z=R or very close
X=0
This is where the antenna is truly resonant = greatest efficiency.
This normally occurs at about 1.4:1...1.5:1
When you tune the antenna for the "magic 1:1...you will normally see that X has a value Greater than 0...This is called reactance. Reactance (X) causes wasted power.
The trick on the analyzer is where is this point reached.
You need to measure the antenna on several channels.
Channel 1...better/worse
Channel 20...better/worse
Channel 40... better/worse
Looking at not only VSWR but X
If VSWR and X is lower on Ch:1 then then the antenna should be to long
If this occurs on Ch:40 then the antenna is too short
If you run the test in sweep mode as 4string suggested, the analyzer will tell you the point of resonance.
Hope this helps
All the Best
Gary
Well then, you should know that tuning for a "low" SWR will actually decrease the antennas efficiency.
Just how does "tuning an antenna" change the return loss?
As the efficiency increases, so will the VSWR.
I use a similar antenna analyzer as OP. I look at the whole picture. Impedance, reactance, SWR, return loss, factor in things like velocity factor of coax used, etc. Who are you trying to stump or impress?
My original reply to the OP is that his antenna system is obviously not tuned for max efficiency based on the antenna analyzer screenshot he shared and to please show us a picture or describe the setup so we could help him get on the right track.
My original reply to the OP is that his antenna system is obviously not tuned for max efficiency based on the antenna analyzer screenshot he shared and to please show us a picture or describe the setup so we could help him get on the right track.
IF that's a dummyload you have connected to the mfj its a good one,
if that's your antenna your a lucky guy its tuned spot on looking through the length of coax you are using.
if that's your antenna your a lucky guy its tuned spot on looking through the length of coax you are using.
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