understanding the A99,, the 1/2 wave over 1/4 wave bit

[davev8]

Solarcon say the "A99 is a half wave over a quarter wave variable mutual transductance tuned antenna"
i understand the variable mutual transductance bit,, that will be the tuning rings over the inductors i know its not a 1/2 wave physically over a real 1/4 wave as it will make it 9feet longer for 10/11m ..so its ether BS/marketing speak or what i suspect the matching network makes it think its over a 1/4wave ..what i whuld like to know is how is that achieved and what are the pros and cons of this type of matching network for folk not familia i will put a schematic and a photo (credit Tech 833)

 

[Handy Andy]

A lot of assumptions are made in this post for the sake of simplicity of Schematics to working value and ranges to work with - so no flames needed - just trying to open up a discussion with a ball that has been hit so hard it's missing half it's cover - don't ask about what is still left for the rest of the playfield to work with...just open dialogue helps.

Well, need a better photo - but from what I see you've got, is the Loading for a 1/4 wave ACROSS the 1/2 wave - with it's own loading coil. So between the winds, which needs a better photo to count those winds - the ƛ -1/4 wave provides a working impedance for the ƛ- 1/2 Wave to Parallel against - like two coils with one tuned with a capacitor and an air gap to change the "reluctance" coupling the 1/4 wave loading and the 1/2 wave loading - together into one package.

I can see the Red coil winds are possibly that 1/4 wave - but the "capacitor" to load the 1/2 wave element must be located around those tuning rings, this cap / sleeve combo provides an Air Gap for the coil load (your 1/2 wave) and Capacitor so the tuning rings work as the "slug" for the tuning - the 1/4 wave just "loads" the matching network to offset the impedance mis-match of the 1/2 wave being much higher than 50 ohms - so more than likely it's a 1/4 wave or 72 ohm inductive impedance load - parallel with a ~1kOhm 1/2 wave whip tuned to offset the impedance so the 72 ohm and the ~1kOhm 1/2 wave - matches close to 50 ohms...per your schematic...

Xr = 1/(1/R1 + 1/R2)

So 72 ohm (expected from 1/4 W/L Dipole Impedance = 72 ohms and the tuning range of the 1/2 W/L with tuned impedance ~1kOhm....

Solving for 1/4 W/L = 72 or 1/72 = 0.01389
Solving for 1/2 W/L = 1,000 = 1/1000 = 0.001

So = 0.01389 + 0.001 = 0.01489 or 1/0.01489 = 67.2 ohms ...

So the 1/2 W/L (ƛ) expected of 1K ohm and 72 ohm of a dipole 1/4 w/l (ƛ) gives 67.2 ohms expected. or about 1.3 SWR based upon 50 ohm unbalanced impedance to 67 ohm loading impedance.

So amongst the ruins of this post, the 1/2 W/L (ƛ) radiator element and its' airgap tuning rings then provide a much LOWER impedance adjustment than the 1/2 W (ƛ) "high impedance in the Kilo-ohmic range" to lower the SWR - against what looks to be a steady 1/4 wave "shorting coil" load that should give the tuned expected of 72 ohms (or less)

The 72 ohms is what a typical 1/4 wave dipole -center fed - exhibits - and that's being forgiving.

So since the LENGTH of 27MHz (at 1/2 ƛ) wavelength is TAD longer than 18 feet - Velocity versus Free air - still can't truly compensate for the shortened length - so it's apparent the capacitor and air gap - offset a length of radiator just under 1/2 wavelength in this package - so the impedance workout is about 900 ohms or just under 1kohm which would fool most meters into thinking you're at a close to 1:1 SWR - but the RESONATE length seems to be a little too short. So, to compensate that - they use a "capacitor" for coupling to the 1/2 Wave - the Inductive Coil added offsets this shortened length. Refer to photo - there's room in length to compress it in there...

There I said it...

I'd like to think all I need to do is update my notes...
"Don't beat me up too Much Scotty...
Uh, Scotty, I said Beat - not Beam...
Oh heck, pass the "Jim Beam" - we all need a shot.."​

 

[Rwb]

A lot of assumptions are made in this post for the sake of simplicity of Schematics to working value and ranges to work with - so no flames needed - just trying to open up a discussion with a ball that has been hit so hard it's missing half it's cover - don't ask about what is still left for the rest of the playfield to work with...just open dialogue helps.

Well, need a better photo - but from what I see you've got, is the Loading for a 1/4 wave ACROSS the 1/2 wave - with it's own loading coil. So between the winds, which needs a better photo to count those winds - the /14 wave provides a working impedance for the 1/2 Wave to Parallel against - like two coils with one tuned with a capacitor and an air gap to change the "reluctance" coupling the 1/4 wave loading and the 1/2 wave loading - together into one package.

I can see the Red coil winds are possibly that 1/4 wave - but the "capacitor" to load the 1/2 wave element must be located around those tuning rings, this cap / sleeve combo provides an Air Gap for the coil load (your 1/2 wave) and Capacitor so the tuning rings work as the "slug" for the tuning - the 1/4 wave just "loads" the matching network to offset the impedance mis-match of the 1/2 wave being much higher than 50 ohms - so more than likely it's a 1/4 wave or 72 ohm inductive impedance load - parallel with a ~1kOhm 1/2 wave whip tuned to offset the impedance so the 72 ohm and the ~1kOhm 1/2 wave - matches close to 50 ohms...per your schematic...

Xr = 1/(1/R1 + 1/R2)

So 72 ohm (expected from 1/4 W/L Dipole Impedance = 72 ohms and the tuning range of the 1/2 W/L with tuned impedance ~1kOhm....

Solving for 1/4 W/L = 72 or 1/72 = 0.01389
Solving for 1/2 W/L = 1,000 = 1/1000 = 0.001

So = 0.01389 + 0.001 = 0.01489 or 1/0.01489 = 67.2 ohms ...

So the 1/2 W/L expected of 1K ohm and 72 ohm of a dipole 1/4 w/l gives 67.2 ohms expected. or about 1.3 SWR based upon 50 ohm unbalanced impedance to 67 ohm loading impedance.

So amongst the ruins of this post, the 1/2 W/L radiator element and its' airgap tuning rings then provide a much LOWER impedance adjustment than the 1/2 W "high impedance in the Kilo-ohmic range" to lower the SWR - against what looks to be a steady 1/4 wave "shorting coil" load that should give the tuned expected of 72 ohms (or less)

The 72 ohms is what a typical 1/4 wave dipole -center fed - exhibits - and that's being forgiving.

So since the LENGTH of 27MHz wavelength is TAD longer than 18 feet - Velocity versus Free air - still can't truly compensate for the shortened length - so it's apparent the capacitor and air gap - offset a length of radiator just under 1/2 wavelength in this package - so the impedance workout is about 900 ohms or just under 1kohm which would fool most meters into thinking you're at a close to 1:1 SWR - but the RESONATE length seems to be a little too short. So, to compensate that - they use a "capacitor" for coupling to the 1/2 Wave - the Inductive Coil added offsets this shortened length. Refer to photo - there's room in length to compress it in there...

There I said it...

View attachment 37190
I'd like to think all I need to do is update my notes...
"Don't beat me up too Much Scotty...
Uh, Scotty, I said Beat - not Beam...
Oh heck, pass the "Jim Beam" - we all need a shot.."​

no matter the figures,my galaxy 99v and radioshack htx 100 get out well,setting on top of a sturdy piece of 2" pipe 30 ' from ground to mount,signal transmitted via Lm 400 low loss coax

 

[Handy Andy]

Can we use that as testimony?

Works for me...

 

[Rwb]

Can we use that as testimony?

Works for me...

i run 50 watt swing on 99v easily talk 75 miles via 38 usb ,30 miles am.
Skip rolling no limit but what skip carrys me on my htx 100

 

[BJ radionut]

http://www.radiomanual.info/schemi/ACC_antenna/Solarcon_A-99_review.pdf

"CLOSING STATEMENTS: The Antron 99 will NOT outperform any of the other typical 5/8 or 1/2 wave antennas like the popular 'Ringo'. However, for a modestly priced fiberglass antenna that is less visually intrusive than the 'ground plane' style antennas, it will certainly meet those needs"

" The Antron 99 has 1.8 dB gain on the horizon over an isotropic radiator. Referenced to a center-fed 1/2 wave dipole, which is the industry standard, the Antron 99 has a NEGATIVE gain of 0.3 dB."

 

[BJ radionut]

Referenced to a center-fed 1/2 wave dipole, which is the industry standard, the Antron 99 has a NEGATIVE gain of 0.3 dB."

So using these figure in real terms:
Halfwave dipole with 100 watts to the antenna the,
Effective Radiated Power = 100.4 watts
The A99 with 100 watts to the antenna, the ERP = 93.4 watts

So using these numbers as totally correct, the A99 has a 7% LOSS over a dipole under equal conditions....???
Having compared side by side with the good OLD Ringo antenna, I tend to believe they are reasonably correct IMHO

 

[Riverman]

So using these figure in real terms:
Halfwave dipole with 100 watts to the antenna the,
Effective Radiated Power = 100.4 watts
The A99 with 100 watts to the antenna, the ERP = 93.4 watts

So using these numbers as totally correct, the A99 has a 7% LOSS over a dipole under equal conditions....???
Having compared side by side with the good OLD Ringo antenna, I tend to believe they are reasonably correct IMHO

That said, I suspect a listener on the other end would not be able to discern the difference between the 100.4 watt station and the 93.4 watt one.
Or, if using a typical barefoot CB, 4 watts and 3.72.

 

[BJ radionut]

That said, I suspect a listener on the other end would not be able to discern the difference

Yes Riverman, I would agree.
However, let us go a step further using these numbers.
Again using 100 watts to the antenna.
A half-wave ground plane having 1.5 dB gain over a Dipole...
ERP = 141.2 watts equates to a 34% increase over the A99
The 5/8ths ground plane having 2 dB gain over a Dipole...
ERP = 158.5 watts equates to a 41% increase over the A99
Now using these reasonable numbers we can begin to show a discernable difference if all antenna conditions are equal.
All the Best
Gary

I am not saying these are TRUE real-world numbers, just this old math major having fun playing with his pad and pencil.

 

[davev8]

A lot of assumptions are made in this post for the sake of simplicity of Schematics to working value and ranges to work with - so no flames needed - just trying to open up a discussion with a ball that has been hit so hard it's missing half it's cover - don't ask about what is still left for the rest of the playfield to work with...just open dialogue helps.

Well, need a better photo - but from what I see you've got, is the Loading for a 1/4 wave ACROSS the 1/2 wave - with it's own loading coil. So between the winds, which needs a better photo to count those winds - the ƛ -1/4 wave provides a working impedance for the ƛ- 1/2 Wave to Parallel against - like two coils with one tuned with a capacitor and an air gap to change the "reluctance" coupling the 1/4 wave loading and the 1/2 wave loading - together into one package.

I can see the Red coil winds are possibly that 1/4 wave - but the "capacitor" to load the 1/2 wave element must be located around those tuning rings, this cap / sleeve combo provides an Air Gap for the coil load (your 1/2 wave) and Capacitor so the tuning rings work as the "slug" for the tuning - the 1/4 wave just "loads" the matching network to offset the impedance mis-match of the 1/2 wave being much higher than 50 ohms - so more than likely it's a 1/4 wave or 72 ohm inductive impedance load - parallel with a ~1kOhm 1/2 wave whip tuned to offset the impedance so the 72 ohm and the ~1kOhm 1/2 wave - matches close to 50 ohms...per your schematic...

Xr = 1/(1/R1 + 1/R2)

So 72 ohm (expected from 1/4 W/L Dipole Impedance = 72 ohms and the tuning range of the 1/2 W/L with tuned impedance ~1kOhm....

Solving for 1/4 W/L = 72 or 1/72 = 0.01389
Solving for 1/2 W/L = 1,000 = 1/1000 = 0.001

So = 0.01389 + 0.001 = 0.01489 or 1/0.01489 = 67.2 ohms ...

So the 1/2 W/L (ƛ) expected of 1K ohm and 72 ohm of a dipole 1/4 w/l (ƛ) gives 67.2 ohms expected. or about 1.3 SWR based upon 50 ohm unbalanced impedance to 67 ohm loading impedance.

So amongst the ruins of this post, the 1/2 W/L (ƛ) radiator element and its' airgap tuning rings then provide a much LOWER impedance adjustment than the 1/2 W (ƛ) "high impedance in the Kilo-ohmic range" to lower the SWR - against what looks to be a steady 1/4 wave "shorting coil" load that should give the tuned expected of 72 ohms (or less)

The 72 ohms is what a typical 1/4 wave dipole -center fed - exhibits - and that's being forgiving.

So since the LENGTH of 27MHz (at 1/2 ƛ) wavelength is TAD longer than 18 feet - Velocity versus Free air - still can't truly compensate for the shortened length - so it's apparent the capacitor and air gap - offset a length of radiator just under 1/2 wavelength in this package - so the impedance workout is about 900 ohms or just under 1kohm which would fool most meters into thinking you're at a close to 1:1 SWR - but the RESONATE lengthht seems to be a little too short. So, to compensate that - they use a "capacitor" for coupling to the 1/2 Wave - the Inductive Coil added offsets this shortened length. Refer to photo - there's room in length to compress it in there...

There I said it...

View attachment 37190
I'd like to think all I need to do is update my notes...
"Don't beat me up too Much Scotty...
Uh, Scotty, I said Beat - not Beam...
Oh heck, pass the "Jim Beam" - we all need a shot.."​

i will have to read that sevral times ..more photos here http://www.radiomanual.info/schemi/ACC_antenna/Solarcon_A-99_review.pdf

 

[Riverman]

Yes Riverman, I would agree.
However, let us go a step further using these numbers.
Again using 100 watts to the antenna.
A half-wave ground plane having 1.5 dB gain over a Dipole...
ERP = 141.2 watts equates to a 34% increase over the A99
The 5/8ths ground plane having 2 dB gain over a Dipole...
ERP = 158.5 watts equates to a 41% increase over the A99
Now using these reasonable numbers we can begin to show a discernable difference if all antenna conditions are equal.
All the Best
Gary

I am not saying these are TRUE real-world numbers, just this old math major having fun playing with his pad and pencil.

10-4. Roger that.
Over and out.

 

[Rwb]

It works main thing. And im getting decent range with my a 99.dont tell it that its not good

 

[bob85]

The advertising claiming the 5/8 has db's of gain over other antennas is misleading or downright lies depending on how dumb the manufacturer is,

They use data from almost a century ago gleaned from ground mounted antennas over massive perfect groundplanes as a referance to BS you,

when you put them above real earth on poles with few radials that all goes out the window,
at the same tip height the 5/8 has a little less low angle gain than a dipole,

most of the difference seen in cb vertical antenna comparisons comes from the mast & coax radiating because folk don't install them correctly,

not because one antennas is way better than another similar length antenna as the cb antenna makers would have you believe.

 

[Handy Andy]

i will have to read that sevral times ..more photos here http://www.radiomanual.info/schemi/ACC_antenna/Solarcon_A-99_review.pdf

Thank you...for a big guess on my end - I guess I owe an apology but too, looking over this the only error I see in my wording if from the 72 PRESUMED - it should have been more 50 ohms - but taking a look at the internals I can also understand why this thing just "radiates" in the down lead of coax too...

Now in the article, he mentions dBi - which is gain over Isotropic. I'm not even going to go there, it's in the realm of Dummy loads.

But I do see the correlation of 1/4 wave wound coil and it's impedance to run against - parallel to, the 1/2 Wave length radiator - the Capacitor assembly or the overall assembly - wow - you just can't make this stuff up.

 

[kopcicle]

"Most of the radiation is up in the sky at a high angle. The angle is so high, it is even useless for skywave.

This is a NEGATIVE gain antenna at low angles. A 1/4wl ground plane would seriously outperform the I-MAX 2000 or any other 1/2 or 5/8th wl antenna that does not have a large ground plane.

This pattern is over real earth, where a conventional dipole has about 8 to 8.5 dBi gain. This antenna about -2 dBd gain maximum. It has negative gain over a dipole. The gain over a dipole at most useful angles for DX is about -10 dB....significant negative gain."

~W8JI

I'll give you this. Any of these antennas (A99, Solorcon,Imax) are better than no antenna but nearly any antenna is better .