Outdoor Loop

[HomerBB]

I have a loop in the attic, but I decided to take a loop outdoors, so I built a 11 meter quad loop and parked it horizontally at 30' elevation.
It is only 10' above the roof ridge. Here are some photos of the building process. Just ask if you don't follow the photos.

 

[binrat]

Looks good, just need a director and reflector and you will be rocking.

 

[HomerBB]

Yep. Maybe later. The difficult part is done.
With the SWR meter it is 1.1:1 on all CB freqs.
I'll get the analyzer on it maybe tomorrow.

 

[Robb]

Just a bit surprised that the metal "X" in the middle didn't make the SWR impossible.
Most of the 'Skypper' loop antennas use fiberglass.
Want to hear you on the air with it Homer.

Can't wait to see what you will do next . . .

 

[W5LZ]

I'm definitely interested in what that analyzer says. I don't believe that 1.1:1 SWR unless that feed line has a matching section in it.
- 'Doc

 

[HomerBB]

I'm definitely interested in what that analyzer says. I don't believe that 1.1:1 SWR unless that feed line has a matching section in it.
- 'Doc

Doc, it has a 1/4ƛ 75 Ohm matching section on it.

 

[HomerBB]

Just a bit surprised that the metal "X" in the middle didn't make the SWR impossible.
Most of the 'Skypper' loop antennas use fiberglass.
Want to hear you on the air with it Homer.

Can't wait to see what you will do next . . .

The X is not a resonant length at these frequencies.

 

[Marconi]

Just a bit surprised that the metal "X" in the middle didn't make the SWR impossible.
Most of the 'Skypper' loop antennas use fiberglass.
Want to hear you on the air with it Homer.

Can't wait to see what you will do next . . .

Robb, IMO it looks like the wire ends of the metal X supports are about 40% PVC and that should allow this one to work OK.

Homer is this laying down flat? If so, how do you think that affect polarity? Is the one in the attic laying down? How do those two compare in performance?

 

[Robb]

Doc, it has a 1/4ƛ 75 Ohm matching section on it.

Do you have details as to how you made the matching section?
The pic isn't very clear on that point.
Is it a matching stub using 75 ohm coax too?
Details please . . .

 

[HomerBB]

Robb, IMO it looks like the wire ends of the metal X supports are about 40% PVC and that should allow this one to work OK.

Homer is this laying down flat? If so, how do you think that affect polarity? Is the one in the attic laying down? How do those two compare in performance?

I only just got it up before i had to quit and go to the Christmas party for the store. I will run them against each other and see. In my opinion, lying horizontal as it is, it is horizontal polarity.

 

[HomerBB]

Do you have details as to how you made the matching section?
The pic isn't very clear on that point.
Is it a matching stub using 75 ohm coax too?
Details please . . .

I simply took a piece of 75 Ohm RG59 coax of 6' in length. I put a proper HF female connector on one end where I used a common barrel connector back to 50 Ohm coax. The other end is attached to the tee where the wire loop terminates. I attached this end of the matching section within the tee via the SS bolts/nuts.
I can fill that tee with silicone for water proofing when I'm satisfied the antenna is resonant where I want it.

 

[W5LZ]

I didn't see that you were using a matching section, so doubted the SWR. I can believe it now. I'm still interested in those analyzer readings though, they ought'a be interesting all by themselves.
If/when you make that comparison, I think you'll find that there may not be as much of a difference as you might (or I might) think.
- 'Doc

 

[HomerBB]

I didn't see that you were using a matching section, so doubted the SWR. I can believe it now. I'm still interested in those analyzer readings though, they ought'a be interesting all by themselves.
If/when you make that comparison, I think you'll find that there may not be as much of a difference as you might (or I might) think.
- 'Doc

I am interested in them, too. I wish it were a 259, but it's a 209, so no digital readout, just the SWR reading. However, it is engineered to give a 1.0:1 only where the right parameters are. It will tell me where resonance is.

 

[Marconi]

I didn't see that you were using a matching section, so doubted the SWR. I can believe it now. I'm still interested in those analyzer readings though, they ought'a be interesting all by themselves.
If/when you make that comparison, I think you'll find that there may not be as much of a difference as you might (or I might) think.
- 'Doc

'Doc, I quizzed Homer on his meter before in asking, if it showed real close or the same SWR value as his in-line meter at the same point in the feed line, but I don't recall what his response was.

I think Homer's meter only does SWR, so your probably not going to get vector analyzer results. I think this one just allows him a much larger range of frequencies to test SWR when checking the bandwidth or looking for the lowest point of SWR vs. being within the range of his CB radios.

Is that right Charles?

I stand corrected. I don't know what the parameters are, but Charles answered 'Doc's and my question. The reason I question this is because many antennas are not resonant where the lowests SWR is indicated. Charles have you checked to see if this is works out to be ture, if you can tell?

 

[HomerBB]

Marconi, according to the manual on this MFJ-209 this instrument will only show a flat SWR at the exact point of resonance.

SWR is the ratio of a load impedance to source impedance. Since nearly all feedlines and
radio equipment used in amateur service are 50 ohms, this instrument is designed to measure
the system SWR normalized to 50 ohms. For example a 150 ohm load placed across the
"ANTENNA" connector will give an SWR reading of 3:1 .
The MFJ-209 measures actual SWR. The load must be 50 ohms of pure resistance for a meter
reading of 1:1 . The common misconception that 25 ohms of reactance and 25 ohms of
resistance in a load will give a 1:1 SWR is absolutely untrue. The actual SWR in this
condition will be measured as 2.6:1 . The MFJ-209 is not "fooled" by mixtures of reactive
and resistive loads.

Hopefully I understand what it is saying.