Sirio GPE 5/8w and GPS 1/2w antennas..

[SuperNasty]

I have a problem understanding the Sirio basic endfed antennas, namely the Sirio GPE 27 5/8 wave and the Sirio GPS 27 1/2 wave.

Here goes!

BOTH of the Sirio antennas are 19ft 6 inches tall, the 5/8 wave and the 1/2 wave. Both antennas also come with an additional 3ft odd adjustable steel top rod that sits in the top to adjust the SWR, (Sirio provides a chart with guide sizes for each antenna that this top rod should be set at).

So, according to the sirio guide for a frequency of say 27.5 MHz the top rod should be set at 19 inches for the GPE 5/8 wave, so thats 19 inches on top of the 19ft 6 inches, bringing the total to 21ft and 1 inch for the GPE 5/8 wave.

For the same frequency, the same chart says that the top rod should be set at 22 inches for the GPS 1/2 wave, so thats 22 inches on top of the 19ft 6 inches, bringing the total to 22ft and 4 inches for the GPS 1/2 wave.

Question 1, how is it possible that the 22ft and 4 inches height of the GPS can be a half wave antenna? actually it's neither 1/2 wave or 5/8 wave height...?

Now the coils at the base on both antennas are visible through clear plastic and the most recent images show identical coils on both, (about 5 turns of copper then a gap then another 5 or so turns of copper).

Question 2, Should the matching network/coils on a 5/8w and 1/2w not be different for the different impedances?

Other than that the only thing I can see different on these two antennas is the addition of the ground plane radials that come with the GPE 5/8 wave.

Anyway I have a Sirio GPS 1/2 wave, and what's started me off thinking about all this is..,

Question 3, if I add radials to the base of my 1/2 wave GPS antenna will it perform better than without them? and will it actually be equal to the performance of the GPE 5/8 wave?

My query is a bit drawn out but you can understand why I am a bit miffed at this.

73s

 

[0926]

I think my question is how do either preform compared to other aluminum antennas? I have thought the same of the 1/2wave and not sure which to buy or go American made.

 

[Oldme]

Interesting.
The Sirio GPE 27 5/8 wave is on the shortest list for a
new setup here.

Reviews I find speak highly.
Wish I could add more.
Hopefully soon I will learn more about this one.

 

[0926]

Am really looking at the Sirio Tornado 27 for $89 plus ride it seems to be a great antenna, spec look as good as Maco v58, workman, Jetstream all about the same looked a youtube videos on the t27 and the amount of high wind it can take. its really a hard choice.

 

[Henry HPSD]

http://s3.zetaboards.com/copythat/topic/7653910/1/

 

[Marconi]

I have a problem understanding the Sirio basic endfed antennas, namely the Sirio GPE 27 5/8 wave and the Sirio GPS 27 1/2 wave.

Here goes!

BOTH of the Sirio antennas are 19ft 6 inches tall, the 5/8 wave and the 1/2 wave. Both antennas also come with an additional 3ft odd adjustable steel top rod that sits in the top to adjust the SWR, (Sirio provides a chart with guide sizes for each antenna that this top rod should be set at).

So, according to the sirio guide for a frequency of say 27.5 MHz the top rod should be set at 19 inches for the GPE 5/8 wave, so thats 19 inches on top of the 19ft 6 inches, bringing the total to 21ft and 1 inch for the GPE 5/8 wave.

For the same frequency, the same chart says that the top rod should be set at 22 inches for the GPS 1/2 wave, so thats 22 inches on top of the 19ft 6 inches, bringing the total to 22ft and 4 inches for the GPS 1/2 wave.

Question 1, how is it possible that the 22ft and 4 inches height of the GPS can be a half wave antenna? actually it's neither 1/2 wave or 5/8 wave height...?

Now the coils at the base on both antennas are visible through clear plastic and the most recent images show identical coils on both, (about 5 turns of copper then a gap then another 5 or so turns of copper).

Question 2, Should the matching network/coils on a 5/8w and 1/2w not be different for the different impedances?

Other than that the only thing I can see different on these two antennas is the addition of the ground plane radials that come with the GPE 5/8 wave.

Anyway I have a Sirio GPS 1/2 wave, and what's started me off thinking about all this is..,

Question 3, if I add radials to the base of my 1/2 wave GPS antenna will it perform better than without them? and will it actually be equal to the performance of the GPE 5/8 wave?

My query is a bit drawn out but you can understand why I am a bit miffed at this.

73s

SuperNasty I'm a little surprised that nobody addressed your questions 1 & 2. Henry did give a link to a brief discussion about question #3.

Personally I don't think radials added to this 1/2 wave will show any improvement, but I'm not sure the Sirio GPS 27 is a 1/2 wave either.

Reason being, if you're right, the antenna appears to be a duplicate of the GPE 27 5/8 wave, but without radials.

Try your best, but I don't think you are likely to see a bit of difference between these two...that you can tell just using your radio.

Sometimes Sirio claims stuff that just don't make good sense.

 

[Henry HPSD]

Some seem to be "fixed" on length...
There seems to be a "magical" 0,625 wavelength or 0,64 I forgot who wins the price. Claims are: that maxes the "best" radiator etc.
If anyone thinks they can measure the difference between 0,64 or 0,625 wl in signal strength, i recommend to think again (unless you work for the voice of america or something similair hihi)

Besides, most calculate the "electrical length without considering the shorting effect of the material used and the shorting effect of diameter.
Those could "set" to a calculated 0,625 wl long antenna to be actually 0,64 wl.

So, now we have esthablished wl of a vertical can "vary".
We take another look at the sirio gpe 5/8 or 1/2 wave.
It is at 27,0 MHz about a 1/2 wave (0,53 wl long ....roughly)
Of course with a higher frequency the radiator becomes electrically longer...
and visa versa with a lower frequency.

Why would sirio make a 5,9 Meter antenna ? (0,53 wl long)
Heck, perhaps its "stock" aluminium ?
perhaps this length came in handy with matching (reactance etc)
perhaps an engineer said : ...well we need to make it slighly longer, so we can make the "claim" 5/8 wave, nobody will notice...and the antenna is longer !
Etc.
That its a commercial thingy, becomes clear that they are both identical antennas.
one with additonal radials, but if you watch close you can see the holes on the 1/2 wave to attach the radials as well.
Im sure selling the same antenna with those two different claims will provide a few more clients.

Just to have it said:
What i find strange is that the topic starter has said 22 foot (6,7m,) total lenght, where the manual provides 5,9 meter for both.

In apect to the question asked:

BOTH ARE IDENTICAL ANTENNAS.
For that reason there is no difference in "matching". Yes, if you would have either a 1/2 wave or a 5/8 wave antenna you can expect differences.
But again, they are identical.
With the exeption of one has radials.


In aspect to the radials ill repeat the answer provided.
Hello Patrick,

They can help...The key word is "can".

They are known to "help" reduce commen mode currents and enhance efficiency.
Especially for those running high power it is usefull to add them.

With that said, in most cases the "normal" cb guy wont notice difference.

In aspect to length..
When using "few" you can use "short" radials.
The difference between 2,5 and 1 meter long radials can not be noticed.
(with the amount you mention).

And still use a RF choke...but now directly below the antenna.

Now, this is something most wont tell you:
With other end fed halve waves(with radials).
It is advised to place the choke several feet below the antenna.
as the commen mode currents can go on the outer braid before they are "choked"...


Hope it was of use patrick !

Kind regards,

H.

PS marconi, you seem to be way to friendly...sometimes it makes no sence ?
I consider it in this case to be: lying, on purpose misleading buyers, as they do know better. (dont get me wrong here ...in some cases im actually a sirio fan !)

Hope it is of use !

Kind regards,

H.

 

[Oldme]

A strange twist to the replies.

My searched shows:
TORNADO 27/58 CB BASE ANTENNA
*Height: Approx. 24ft (7230mm)
http://www.hyelectronics.com/TORNADO-27_58-CB-BASE-ANTENNA/productinfo/TORNADO+27_58/

Maybe there has been a change from the 19.5 ft
initially stated?

Thanks for then information.

 

[Henry HPSD]

The topic starter is asking about the gpe and gps antennas of sirio.

the tornado is at different antenna.
it seems to be a step up from those others, from a electrical aswell a mechanical point of view.

 

[Oldme]

Thanks.
I had the two 5/8s confused.

 

[Marconi]

SuperNasty I think you are very close on your comparison of the dimensions on these two Sirio antennas. According to the manual they are both identical at 19' 6" from the bottom of the coil to the top of the extended 5 element whip.

The tip element, #2 in the manual with the basket on top, does make a little difference in the overall length for these two antennas, and it is noted as the tuning point for both the 5/8 & 1/2 wave.

There is very little difference between these to radiators, and there should be about 4' to 5' considering the math/wavelength differences.

I note however in the attached link there looks to be a bit of difference between the two coils, but it still doesn't look like a difference that explains the difference in the overall lengths for these two:

http://www.sirioantenne.it/prodotti_tec_ant.php?idp=57&idg=1008171169&idc=1008171241

 

[HotrailsStratPlayer]

I had both and the 5/8th with its three radials worked a lot better the the half wave, gps, My test was on a guy 25 miles away s1 radio 3 on the gps s3 radio 5 on the gpe, both mounted on the same pole,

 

[0926]

GUYS please do yourself a favor and leave the siro's brands alone, spend the extra $$$ and get a HYGAIN Penetrator SPT500, Believe me you will not be sorry. none better. the only antenna BANDED by the FCC for 11 meter use, why because it is so damn good. all aluminum and can run on 10,11,12 meters.

 

[The DB]

GUYS please do yourself a favor and leave the siro's brands alone, spend the extra $$$ and get a HYGAIN Penetrator SPT500, Believe me you will not be sorry. none better. the only antenna BANDED by the FCC for 11 meter use, why because it is so damn good. all aluminum and can run on 10,11,12 meters.

Oh look, a Hy-Gain fanboy...

Look, that Hy-Gain Penetrator is a great antenna. I would have no problem recommending it. That being said...

The only antenna banned by the FCC? There is no truth to that statement, at all. The law is that manufacturers are not allowed to sell aluminum antennas for use on the CB band, and applies to any antenna that can fall across power lines and either kill you from electrocution, or cause other damage to power equipment. That means it applies to EVERY aluminum antenna on the market, not just your baby. Note, that doesn't mean you can't put one up and use it on 11 meters, it just means they cannot sell you the antenna for use on 11 meters...

Also, there are two vertical antenna designs that many here on this forum, and others as well, have multiple reports of outperforming 5/8 wavelength antennas, including your Penetrator. They are both made by Sirio... Wait, didn't you tell us to ignore that company? Perhaps you should pay more attention to that company intead of warning us away from them.


The DB

 

[0926]

If what you say is truth, then SIRO and any other company that makes or sells ALL ALUMINUM antennas for CB use of the 11 meter band, can not sell or market their antennas because they too might fall into power lines killing or destroying equipment, and so by that statement, no other ALL aluminum antenna for 10 meter band or any other meter band can be manufactured or sold because of the same reason, so you are so wrong, the ONLY reason and you can actually look it up, is the FCC (FCC’s Office of Engineer and Technology) banned the sell and marketing of the HYGAIN SPT500 Penetrator antenna for 11 meter band use and only the SPT500, not the CLR2 the 1/2 5/8 and the 64wave and the STAR DUSTER which were all aluminum sold by Hygain, Radio Shack and all others, and not because it was an OMIN-DIRECTIONAL, not because it was aluminum and might fall into or on electrical power lines killing or destroying equipment, but because it gave the 11 meter (CB) band a superior transmitting range exceeding the 10 miles limit set forth by the FCC’s Office of Engineer and Technology, according to the FCC Rules for Amateur Radio Service.. Antenna's whether ALL ALUMINUM or fiberglass have no transmission limits on any other band.