UHF antenna?
- Thread starter trb012
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ianf
Member
Which GME antenna?
Or you could check out Watts Communications at 68-70 Kembla Street Fyshwick ACT 2609 (02) 6280 6416. They sell RFI & GME antennas.
Or you could check out Watts Communications at 68-70 Kembla Street Fyshwick ACT 2609 (02) 6280 6416. They sell RFI & GME antennas.
terryc
Member
An antenna NOT to buy is the GME 409L
http://www.gadgetcity.com.au/gme-ae409l-6/9-db-antenna-p-446.html?cPath=92_23_119
The various sections are held together by grub screws, which vibrate loose all the time.
Purchased it and a unity stick before we went away and the 9dB option jumped out of the base twice before I gave it a really tough tighten up. so to top it off, The Boss then started throwing it away piece by piece from the top. Had to swap over to the 6db option, which thankfully lasted the distance.
Can not really comment on range as the 409L was bullbar mounted and the unity stick hood mounted. Both into a handheld, but both were fine for tag-alog-convoy work.
http://www.gadgetcity.com.au/gme-ae409l-6/9-db-antenna-p-446.html?cPath=92_23_119
The various sections are held together by grub screws, which vibrate loose all the time.
Purchased it and a unity stick before we went away and the 9dB option jumped out of the base twice before I gave it a really tough tighten up. so to top it off, The Boss then started throwing it away piece by piece from the top. Had to swap over to the 6db option, which thankfully lasted the distance.
Can not really comment on range as the 409L was bullbar mounted and the unity stick hood mounted. Both into a handheld, but both were fine for tag-alog-convoy work.
DaSmeg
Member
Hi guys, it's been awhile with this stuff but don't quote me, but the higher the db gain the better it is in hilly country but crap for long range but lower db gain is better for long range ( flat country) try and get some thing around the 6 db gain as it is always a good compromise, in saying that unless you have a repeater station up ya clicker UHF is really only good for say 10k distance or vehicle too vehicle comms but like I said don't quote me 
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Krankin
Guest
Hi guys, it's been awhile with this stuff but don't quote me, but the higher the db gain the better it is in hilly country but crap for long range but lower db gain is better for long range ( flat country) try and get some thing around the 6 db gain as it is always a good compromise, in saying that unless you have a repeater station up ya clicker UHF is really only good for say 10k distance or vehicle too vehicle comms but like I said don't quote me
check out the pics......
LLadnar
Member
Can you run dual antenna's? say a 8or6 db and a 3 db so that you have both long range and hilly coverage at the same time? if yes how do you go about wiring it up?
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Krankin
Guest
Geoff3DMN
Member
With a changeover switch one isn't running both antennas at the same time, you're just choosing which one you're running (still useful but not the same thing).
If you go down this path then make sure you buy a switch rated for UHF use, some of them are only designed for HF (like the cheap 27Mhz CB ones).
Something like the Diamond CX-210A would work well.
http://www.universal-radio.com/catalog/switch/1636.html
At the cheaper end of the scale this MFJ would work ok.
http://www.universal-radio.com/catalog/switch/2811.html
If you go down this path then make sure you buy a switch rated for UHF use, some of them are only designed for HF (like the cheap 27Mhz CB ones).
Something like the Diamond CX-210A would work well.
http://www.universal-radio.com/catalog/switch/1636.html
At the cheaper end of the scale this MFJ would work ok.
http://www.universal-radio.com/catalog/switch/2811.html
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Geoff3DMN said:
They don't look very user friendly.
By that I mean my radio is mounted up under the dash. I'd have to crawl under there to switch it over
However by all means that's a nifty solution
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Geoff3DMN
Member
Normally you run an antenna patch cable from the UHF to the switch box the mount the switch somewhere easy to access.
ianf
Member
Interesting discussion however runnning 2 antennas with a switch is overkill.
If we can get back to some 'basic' antenna theory. A unity gain antenna has 2.14 dBi of gain. This antenna has a high angle of radiation and is good for short range or hilly terrain.
Add more gain (most 4wd"ers run a 5-6 dBi elevated feed ground independant antenna) and you lower the angle of radiation and hence get longer range with a slight reduction in performance hilly/mountainous terrain.
Add more gain again, say a 8 dBi antenna, the angle of radiation is further lowered. These antennas are great for deserts (flat terrain) and provide the longest range.
So its about getting a good compromise. so a 5-6 dBi antennas are the way to go for gerneral use.
You can purchase antennas where you can switch the the 'whips' over to provide you with say a 5 dBi whip for general use and a seperate 8 dBi whip for flat terrain and hence longer range.
The other things to think about are:
1) Buy a ground independation antenna.
2) Mount the antenna as high a possible away from other other antennas/obstructions.
3) and finally buy a good quality antenna. The ones that come free with the radios and just that. Remember "there's no such thing as a free lunch".
If we can get back to some 'basic' antenna theory. A unity gain antenna has 2.14 dBi of gain. This antenna has a high angle of radiation and is good for short range or hilly terrain.
Add more gain (most 4wd"ers run a 5-6 dBi elevated feed ground independant antenna) and you lower the angle of radiation and hence get longer range with a slight reduction in performance hilly/mountainous terrain.
Add more gain again, say a 8 dBi antenna, the angle of radiation is further lowered. These antennas are great for deserts (flat terrain) and provide the longest range.
So its about getting a good compromise. so a 5-6 dBi antennas are the way to go for gerneral use.
You can purchase antennas where you can switch the the 'whips' over to provide you with say a 5 dBi whip for general use and a seperate 8 dBi whip for flat terrain and hence longer range.
The other things to think about are:
1) Buy a ground independation antenna.
2) Mount the antenna as high a possible away from other other antennas/obstructions.
3) and finally buy a good quality antenna. The ones that come free with the radios and just that. Remember "there's no such thing as a free lunch".
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Krankin
Guest
Thanks for that^^
tho the question was "can you run two antenna's at the same time"?
tho the question was "can you run two antenna's at the same time"?
Geoff3DMN
Member
You can run 2, 3, 4 or more antennas by using a phase delay connection harnesses.
This is normally used to achieve directionality and you get odd and difficult to predict results unless the antennas are of the same general type and mounted specific distances apart in particular patterns.
It's not of much use for car use because the primary purpose is to create directionality (like a beam antenna).
A multi position switch can be combined with a 3 or 4 vertical antenna system, and multi length phasing harnesses to create switchable directions of maximum gain.
I used to use a 9dbi antenna which was too long for car parks (so it was removed for city use) and a unity gain whip (2.1dbi) combined with a 2 way switch. I'd remove the long antenna for city use and switch to the short one then on a trip I'd fit the long one and switch to that so I could run two antennas on my vehicle at the same time (but not use them at the same time).
As the previous posted has pointed out however this is of little advantage now that antennas are available with different length top sections (for selectable length/gain).
If you're trying to achieve simultaneous high and low gain antenna patterns for hilly and flat country then that's simply not the way things work, it is NOT an achievable goal. That's not the way phased antennas work, they just increase gain in a particular direction.
A common usage for phased arrays is UHF TV antennas (like this picture)
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Krankin
Guest
Yes...thanks, but I allready know that answer, i was just getting back to the question asked by another member before it got too OT,
tho the ants you mention arent for our purpose or can be fitted to a vehicle...all those are directional ant's and not omni's like we use for our UHF's on our trucks.
QUOTE:
["If you're trying to achieve simultaneous high and low gain antenna patterns for hilly and flat country then that's simply not the way things work, it is NOT an achievable goal."]
No as i said...its a no unless one uses a changover switch...which means..only one ant at a time...personnaly I wouldnt wast my time going that way for a vehicle.....maybe at a home base.
tho the ants you mention arent for our purpose or can be fitted to a vehicle...all those are directional ant's and not omni's like we use for our UHF's on our trucks.
QUOTE:
["If you're trying to achieve simultaneous high and low gain antenna patterns for hilly and flat country then that's simply not the way things work, it is NOT an achievable goal."]
No as i said...its a no unless one uses a changover switch...which means..only one ant at a time...personnaly I wouldnt wast my time going that way for a vehicle.....maybe at a home base.
LLadnar
Member
LOL... so after all that its just a simple no, you can't run two antenna's at the sametime.
thanks for the effort guys, would be a good invention too work on for someone with the knowledge.
thanks for the effort guys, would be a good invention too work on for someone with the knowledge.
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