Detachable antennae: PMR446 vs. Wifi

Licence free two-way radio services that now includes both FM and digital channels. Discuss models, modifications and other similar worldwide standards such as FRS and GMRS.
troffasky
Super Member
Super Member
Posts: 341
Joined: 18 Jul 2010, 14:58

Detachable antennae: PMR446 vs. Wifi

Post by troffasky »

Why is it that the above is verboten on PMR446, but OK for the arguably more heavily contended 2.4GHz wifi band?
User avatar
26CAB40
Veteran
Veteran
Posts: 2537
Joined: 05 Aug 2008, 17:42
Location: £200 Jacksonville

Re: Detachable antennae: PMR446 vs. Wifi

Post by 26CAB40 »

Not really comparable.
One is for short range voice comms over 1km or so, the other is to provide wideband data services within a short range.
Chalk & cheese.
"It's worth whatever they're willing to pay"
troffasky
Super Member
Super Member
Posts: 341
Joined: 18 Jul 2010, 14:58

Re: Detachable antennae: PMR446 vs. Wifi

Post by troffasky »

Sorry I wasn't clear in my OP. I meant in regulatory terms, not technical ones.
User avatar
26CAB40
Veteran
Veteran
Posts: 2537
Joined: 05 Aug 2008, 17:42
Location: £200 Jacksonville

Re: Detachable antennae: PMR446 vs. Wifi

Post by 26CAB40 »

Domestic Wi-Fi installations are not usually the target for hi-gain external antennae, we must presume they are for commercial installs.
The antennae available over the web, being sold to consumers probably exist within a 'grey zone' in that respect.
They are usually from international sources where regulations may vary.

Microwave equipment installed in commercial premises has to conform to many regulations of course.

External antennae for PMR446 are illegal.
"It's worth whatever they're willing to pay"
User avatar
Guzzy
Veteran
Veteran
Posts: 4969
Joined: 24 Feb 2005, 02:33
Call Sign: 26TM002
Location: Kent

Re: Detachable antennae: PMR446 vs. Wifi

Post by Guzzy »

A lot of PMR446 radios use really pathetic and very lossy 'coiled spring' type antennas, if you put a 'proper' UHF antenna on them, you get a significant improvement in performance. Illegally, of course. ;)

There is quite a lot of experimentation with improvised WiFi antennas. You can have loads of fun extending WiFi ranges! :D
User avatar
wind in the antenna
Top Poster
Top Poster
Posts: 1845
Joined: 29 Mar 2010, 17:41
Location: Brighton

Re: Detachable antennae: PMR446 vs. Wifi

Post by wind in the antenna »

The FCC were concerned about people using high gain antennas with WiFi. They brought about what I recall was a voluntarily manufacturers' agreement to use reverse SMA and TNC etc. RF connectors. This duly brought out a market in reverse gender antennas and adaptors and achieved nothing for their cause.

I'm a radio armature who made the switch to ariel none-bio
New Face in Hell

----------------
Tony in Brighton
26TM9480
26FB298
G7TXU
----------------
andykirby
Regular
Regular
Posts: 20
Joined: 26 Jun 2011, 17:56

Re: Detachable antennae: PMR446 vs. Wifi

Post by andykirby »

Agreed with that Guzzy! I can remember years back I bought a little 2.4Ghz magmount to connect to the wifi card in my old PC. Suddenly I could pick up some crazy fast AP from down the street :o
User avatar
wind in the antenna
Top Poster
Top Poster
Posts: 1845
Joined: 29 Mar 2010, 17:41
Location: Brighton

Re: Detachable antennae: PMR446 vs. Wifi

Post by wind in the antenna »

Converted radio equipment
PMR446 users are reminded that their radios are only licence-exempt if they are built and
operated within the conditions of the exemption regulations. If modifications are made to the
equipment, such as adding an antenna connector, the overall maximum ERP or other technical
parameters must not exceed the permitted levels set out in the Interface Requirement.

I'm a radio armature who made the switch to ariel none-bio
New Face in Hell

----------------
Tony in Brighton
26TM9480
26FB298
G7TXU
----------------
User avatar
bigbloke
Top Poster
Top Poster
Posts: 1449
Joined: 25 Aug 2008, 17:53
Location: Nominally Newport (South Wales) but potentially "anywhere"
Contact:

Re: Detachable antennae: PMR446 vs. Wifi

Post by bigbloke »

Hmmm...I've often toyed with the idea of recycling my old pair of Pye PF1's and nightcall unit onto 446 channel 8.

The antenna is definitely built in! :) The power can be wound down to 500mW , but the deviation would be a bit wide.

Have to work out the crystal frequencies and give it a go for some fun.

As for Wifi, before 4W video senders and similar powered CCTV camera senders in 2.4GHz I've had 5mb connections at
around 15 miles and 2Mb (when the tide permitted) at over 35 miles. the problem wasn't the RF signals, but having to use
atheros chipsets with a wireless router distro called Star-OS to enable the round trip ACK timers to be pushed out far enough
to get packets through reliably. And before anyone cries "Foul!" this was on channel1 ...under my ham callsign :)

Regards

BB
User avatar
wind in the antenna
Top Poster
Top Poster
Posts: 1845
Joined: 29 Mar 2010, 17:41
Location: Brighton

Re: Detachable antennae: PMR446 vs. Wifi

Post by wind in the antenna »

TX xtal freq (MHz) = fc / 36
RX xtal freq (MHz) = fc + 10.7 / 5

Crystals in both units are HC18u wire ended

The RX unit was fitted with either FC03219 filters for 25kHz spacing or for earlier issues, FC03208 for 50kHz spacing.

The antenna was often said to be built into many an unwitting rookie coppers right nostril. :lol:

I'm a radio armature who made the switch to ariel none-bio
New Face in Hell

----------------
Tony in Brighton
26TM9480
26FB298
G7TXU
----------------
User avatar
Guzzy
Veteran
Veteran
Posts: 4969
Joined: 24 Feb 2005, 02:33
Call Sign: 26TM002
Location: Kent

Re: Detachable antennae: PMR446 vs. Wifi

Post by Guzzy »

andykirby wrote:Agreed with that Guzzy! I can remember years back I bought a little 2.4Ghz magmount to connect to the wifi card in my old PC. Suddenly I could pick up some crazy fast AP from down the street :o
WiFi homebrewing at it's best:

http://cruftbox.com/cruft/docs/cantenna.html

http://www.turnpoint.net/wireless/cantennahowto.html

The only antenna project that comes with a free novelty lunch on the inside. :lol:

The original intention with these designs was to leach off other WiFi users, not so easy these days, most people have become much more aware of WiFi security.
User avatar
bigbloke
Top Poster
Top Poster
Posts: 1449
Joined: 25 Aug 2008, 17:53
Location: Nominally Newport (South Wales) but potentially "anywhere"
Contact:

Re: Detachable antennae: PMR446 vs. Wifi

Post by bigbloke »

Cantenna ??? PAH !!! :lol: :lol: :lol: :lol:

WAY better off adding a new feedpoint to an old 60cm ASTRA sky dish !
and inverting it so that it looks as though its pointing at the sky not at the
ground .

A good 17dB of gain to be had !!

Wimo in germany used to make a circular polarised feedpoint for OSCAR sattelite
working that used to be a direct replacement for the LNB on these type of dishes.

[edit] couldnt find my picture so here's one from Wimo on an 80cm [/edit]

Image


1m dishes were even more fun :))

Regards

BB
User avatar
fez
Veteran
Veteran
Posts: 3407
Joined: 26 Jan 2007, 19:51
Location: On the computer

Re: Detachable antennae: PMR446 vs. Wifi

Post by fez »

love playing with wifi, Got all sorts of antennas from helical, dish to yagi.

My fav is my commercial 2.4ghz dish.
User avatar
Guzzy
Veteran
Veteran
Posts: 4969
Joined: 24 Feb 2005, 02:33
Call Sign: 26TM002
Location: Kent

Re: Detachable antennae: PMR446 vs. Wifi

Post by Guzzy »

fez wrote:love playing with wifi, Got all sorts of antennas from helical, dish to yagi.

My fav is my commercial 2.4ghz dish.
I'm sorry, but I think you will find it damn hard to beat a Pringle's can.

Sure, it may not have as much gain as some of your fancy shmansy helical, yagi and dish antennas, but the construction process tastes much nicer! :D :lol:
User avatar
wind in the antenna
Top Poster
Top Poster
Posts: 1845
Joined: 29 Mar 2010, 17:41
Location: Brighton

Re: Detachable antennae: PMR446 vs. Wifi

Post by wind in the antenna »

wind in the antenna wrote:
Converted radio equipment
PMR446 users are reminded that their radios are only licence-exempt if they are built and
operated within the conditions of the exemption regulations. If modifications are made to the
equipment, such as adding an antenna connector, the overall maximum ERP or other technical
parameters must not exceed the permitted levels set out in the Interface Requirement.

I'm a radio armature who made the switch to ariel none-bio
New Face in Hell

----------------
Tony in Brighton
26TM9480
26FB298
G7TXU
----------------
Post Reply