Discone antenna and yagi antenna
- Thread starter Colton25
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It's not advisable to do this at the same time, but a vhf yagi would definitely let you hear that distant fire dept!
73,
n9zas
n5ims
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Possible? Yes. Will it help? Perhaps yes, perhaps no. Will it make things worse? Perhaps yes, perhaps no.
You need to be very careful on how you connect them. If you use a switch where only one antenna is connected at a time you'll avoid the issues where a signal arrives on both antennas and the out-of-phase signals mix together and cause distortion or possibly even reducing the signal level to near nothing.
For a full discussion on what you want to do, read this sticky thread on the topic of using multiple antennas with a scanner. http://forums.radioreference.com/passive-devices/113057-running-one-scanner-multiple-antennas.html
It's not advisable to do this at the same time, but a vhf yagi would definitely let you hear that distant fire dept!
73,
n9zas
Yeah I've been doing tons of research!! Looks like the yagi would work great however i don't want to lose my Discone :/
I agree, since there are times when you may not want the directional ability. You could mount the yagi right below your discone.
As suggested above , if care and the proper hardware is used, you could have your discone on a rf switch with a yagi.
Both at the same time will not work well.
73,
n9zas
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What if i use a duplexer rather then a switch??
As n5ims said above, the out of phase signals through a duplexer from both antennas would probably create a attenuated signal, meaning you would not hear as much as being able to pick between either antenna.
73,
n9zas
Okay so i would be better off with a switch then, what do you thin about this switch?
Diamond® Antenna ~ CX210A Heavy Duty Wideband Coax Switch
Yep, that will work if you wish to use both your yagi and discone but keep in mind you will need two pl259/ bnc female adapters. I need a switch like that myself!
73,
n9zas
Yep, that will work if you wish to use both your yagi and discone but keep in mind you will need two pl259/ bnc female adapters. I need a switch like that myself!
73,
n9zas
Okay awesome, and i can put the switch at the scanner end correct?
Is this the yagi you think will work best?..... Y1503 - Antenex Professional Grade Gold Anodized 150-174Mhz 3 Element 7.1dBd Yagi Antenna
Yes...unless you want to climb up there to switch antennas? :lol:
The Y1503 should work for you great unless you want more gain then there are larger yagis with more elements, and as the description mentions the antenna will have three elements and will be much taller than the one pictured since it is vhf.
73,
n9zas
Okay i'm not to worried about the size, it will go under the discone. Out of curiosity would you happen to know how much bigger it will be haha
The longest (rear) element should be around 17" long.
I found this too, which might interest you,
http://www.b2gmarket.com/vendorfiles/product_selection_guide_no price.pdf
good luck!
73,
n9zas
Okay thanks for all the help!! I will post a finished product picture in the antenna forms
majoco
Stirrer
IMHO I wouldn't fork out for a 1.5kW switch for just receiving! Much cheaper switches are around.
kf5qgf
Member
So let's just plant the seed and see where it goes. What about phasing harnesses? I know in theory you can use odd fourths of coax length to help match impedence. Anyways what I'm saying is if you have a yagi, 50 ohm impedence, and a properly built discone, 50 ohm impedence, there is undoubtedly a way to match the impedences back down to 50 ohms so that it will actually be beneficial to use both. Anyways, like I said, just planting the seed, ya'll run with it.
KF5QGF
KF5QGF
True, but some of the cheaper rf switches lack sufficient isolation between the ports. Diamond switches are known for having decent port to port isolation.
Also if he ever decides he wants to transmit, then he'd be set.
73,
n9zas
Craig,
If done correctly you would have the impedance taken care of. But, that doesn't have anything to do with how the signals from both antennas will combine. In phase, out of phase, both are possible and can either increase signals or decrease the desired signals. At the same time all those undesired signals will also be subject to the same increase/decrease. With just a simple feed line connection there's no way to distinguish between desired/undesired signals. It can certainly be done, but it's not a simple thing anymore.
High capability antenna switches are certainly nice to have. In my particular case they would be much more than I'd ever need (transmitting or receiving). So, depending on how 'frugal' I happen to be at the moment ('frugal' = cheap, which is dependent on my finances at any particular time), I could 'make do' with much less. YMMV, naturally.
- 'Doc
If done correctly you would have the impedance taken care of. But, that doesn't have anything to do with how the signals from both antennas will combine. In phase, out of phase, both are possible and can either increase signals or decrease the desired signals. At the same time all those undesired signals will also be subject to the same increase/decrease. With just a simple feed line connection there's no way to distinguish between desired/undesired signals. It can certainly be done, but it's not a simple thing anymore.
High capability antenna switches are certainly nice to have. In my particular case they would be much more than I'd ever need (transmitting or receiving). So, depending on how 'frugal' I happen to be at the moment ('frugal' = cheap, which is dependent on my finances at any particular time), I could 'make do' with much less. YMMV, naturally.
- 'Doc
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