VAS 2.4 folded dipole - RC Groups
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Jun 30, 2017, 08:26 AM
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VAS 2.4 folded dipole


Has anyone used the new VAS 2.4 folded microwave 2.4 dipole? I have done the 5 dbi mod to my Taranis and I think that a 5 dbi antenna puts some strain on the connector. I like how small the antenna is and may be a better option for range.

Thanks
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Jun 30, 2017, 09:19 AM
S.A.D. member
ivanc's Avatar
Quote:
Originally Posted by Axiom7
Has anyone used the new VAS 2.4 folded microwave 2.4 dipole? I have done the 5 dbi mod to my Taranis and I think that a 5 dbi antenna puts some strain on the connector. I like how small the antenna is and may be a better option for range.

Thanks
Any antenna which gives more range makes the signal more directional and the modded device no longer legal in the US and almost everywhere in the world.

Ivan
Jun 30, 2017, 09:48 AM
Registered User
How are homemade ham radio antennas legal then?

Quote:
Originally Posted by ivanc
Any antenna which gives more range makes the signal more directional and the modded device no longer legal in the US and almost everywhere in the world.

Ivan
Jun 30, 2017, 09:50 AM
S.A.D. member
ivanc's Avatar
Quote:
Originally Posted by Axiom7
How are homemade ham radio antennas legal then?
We are talking about 2.4GHz, right? At least I am. If you are a ham you should know better what is legal and what not before posting online.

Ivan
Jun 30, 2017, 10:03 AM
Registered User
Have you used the VAS 2.4 antenna?

Quote:
Originally Posted by ivanc
We are talking about 2.4GHz, right? At least I am. If you are a ham you should know better what is legal and what not before posting online.

Ivan
Jun 30, 2017, 02:45 PM
Registered User
ivanc don't need to use something RF to have an opinion... because his are knowledge based, not trial and error.
Jun 30, 2017, 03:15 PM
Registered User
He just said its illegal, not an opinion on how it worked.

Im going to take a stab and say since its from VAS, its quality.

Not really sure why I asked the question, kind of knew I would get a snarky response from some antenna nazi.

Quote:
Originally Posted by renatoa
ivanc don't need to use something RF to have an opinion... because his are knowledge based, not trial and error.
Jun 30, 2017, 04:07 PM
Perpetual Noob
BoxCar31's Avatar

Ivan's statement


Quote:
Originally Posted by Axiom7
He just said its illegal, not an opinion on how it worked.

Im going to take a stab and say since its from VAS, its quality.

Not really sure why I asked the question, kind of knew I would get a snarky response from some antenna nazi.
Ivanc's statement that the antenna was illegal for sale/use in the US in the 2.4 GHz UNII frequency band should have been an indication to many that he would not have installed or tried it. The radios for which this antenna is targeted all fall within Parts 15 and 18 of the Federal Communications Rules which state that a device may not radiate more than a specific amount (200mw in this case) of RF energy if it is to be used in the Unlicensed National Information Infrastructure band. This particular segment of frequencies does a lot more than control our remote devices, it supports many other uses ranging from WiFi to medical devices and the Bluetooth we like to use to link to our headsets. The rules state that an unlicensed device shall "cause no interference and accept all sources of interference" which is key in getting all the devices to work together. While our RC radios all now change channels within the band rapidly, the interference they may generate is negated by the quick burst of energy before they have moved to another channel. However, increasing the power means that a device that would not experience interference because of its distance from a 200 mw source will receive interference from one with a significant greater amount of radiated energy. Those devices that would have received interference with the normal power may be rendered non-operational during the time the units share a channel and that's the big no-no.
Jun 30, 2017, 04:17 PM
Stuart
srnet's Avatar
Quote:
Originally Posted by Axiom7
Not really sure why I asked the question, kind of knew I would get a snarky response from some antenna nazi.
An alternative response would be thanks, for someone pointing out that what you were proposing was very likely illegal.

Ever heard the saying "dont shoot the messenger"
Jun 30, 2017, 05:50 PM
S.A.D. member
ivanc's Avatar
Quote:
Originally Posted by Axiom7
Have you used the VAS 2.4 antenna?
I would reply that I have not as otherwise I'd be admitting that I have engaged in illegal activities.

Unaltered RF generators put a certain amount of power into the antenna feed. In the 2.4GHz case the 2db antenna is the one which provides the most even signal distribution in almost all directions. Changing the antenna gain does not change the power into the antenna feed if properly done (if improperly done it can lower that amount of power). When using a higher gain antenna the same amount of power is radiated more directionally so you gain range in that particular direction but the range quickly diminishes when the receiver moves out of the maximum radiated power zone, so it is more range but more directional. You always trade range for directionality and vice versa.

As far as legality, 2.4GHz devices are approved by the FCC (and the corresponding authorities in other parts of the world) with the antenna and antenna feed. Altering the antenna and/or the antenna feed renders the device illegal to use. Even adding a connector to make the antenna removable is altering the device from its FCC (other agency in other parts of the world) approved version which makes it no longer legal to use.

I know, they sell "replacement/better" antennas for WiFi routers/WAPs but that does not make them any legal either.

Over and out (of here),
Ivan
Jun 30, 2017, 09:21 PM
Registered User
vollrathd's Avatar
For us older folks, remember what all the illegal high powered transmitters did to the CB radio some years ago. We don't want that to happen on our 2.4 Ghz frequencies.
Jul 01, 2017, 06:49 AM
No bounce, No play.
davidmc36's Avatar
Quote:
Originally Posted by Axiom7
How are homemade ham radio antennas legal then?
Because the Amateur Radio License gives the individual privileges to fabricate antennae and even transceivers. The knowledge they have allows them to know how and what is legal with respect to transmission power and modes on specific frequencies.
Jul 01, 2017, 08:33 AM
Registered User
to be fair though... anyone flying today with a 200 mw 5.8g vtx is outlaw... probably more than 50% of market
Jul 01, 2017, 08:49 AM
Registered User
Quote:
Originally Posted by renatoa
to be fair though... anyone flying today with a 200 mw 5.8g vtx is outlaw... probably more than 50% of market
Not true if you're a ham. (But yes, many use their over-powered and/or unlicensed vtx without a license.)

2.4G digital spread spektrum (what this thread is about) has different rules though.
Jul 01, 2017, 11:48 AM
Sagitta Fanboy
Quote:
Originally Posted by atreis
Not true if you're a ham. (But yes, many use their over-powered and/or unlicensed vtx without a license.)

2.4G digital spread spektrum (what this thread is about) has different rules though.
Very similar rules for 2.4GHz and 5.8GHz (not sure if the power levels are the same, but otherwise the regs are the same, at least in Canada and the US). We just don't tend to use much in the way of 2.4GHz VTX's because they are not compatible with 2.4GHz receivers in the same aircraft (mostly due to swamping issues from having a same-band TX too close to the RX)

A technician-class Ham can legally do an antenna mod to a Taranis in the US or Canada (as the Taranis is under 100mW EIRP, so well under US/Canadian legal limits). But they would be unlikely to as they would understand why it's a false gain (increased directionality is more of a problem than the minor range increase is a gain). Without the license, you cannot as the modified unit would not be legal (and no, you can't ask your Ham buddy to do it for you, they need to be the ones operating or supervising operation of the modified unit)

If the 5dB antenna was really a gain, FrSky would have used them in the units where they could be legal if certified. But it's not a gain, it's a loss and you're more likely to have a loss of signal event from a 5dB setup than from the lower EIRP 2dB antenna.


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