Does anyone know if a 5.12 dB gain antenna is that much different than a 2 dB gain antenna?

Question

I'm looking to buy antenna for my digital scanner to try to pick up more frequencies and hopefuly make weaker ones come in stronger.

I've narrowed it down to two, (Discone antennas), the one with higher gain (5.12 dBi) has fewer arms/points (12) coming out of it, and is a shorter antenna.

But the lower gain (2 dB nominal) actually has more arms/points (16) on it and is 2 feet taller.

I live in a small town and am in a mobile home park, the 2 closest big cities are 30 and 65 miles away.

Would it possibly be better to go with a taller antenna or a shorter antenna w/ higher gain? I have a 15 ft post to put it on.

(The higher gain (shorter) one is made by Comet, and the lower gain (taller) one, is made by Diamond, if "name" brands mean anything-I dunno :)

I am in a wheelchair from MS and am at home 24/7 and so listening to my scanner kindof helps me feel more in touch with the outside world. I'd just like to listen to something other than dogcatchers and the occasional cow getting out-LOL

I have a broken small antenna on it now and occasionally pick up bigger cities when it's snowing out and the clouds are low, so I know I'm getting the signal, I just need to draw it in.



Any suggestions?

Answer 1

A discone is omni directional, so any gain would be at the expense of upward radiation. If you are after aircraft that could be a problem, but for land based stuff, no issue. Be sure the gain figures are the same unit. There is a difference between gain in dbd, dbi and other figures. Typically an antenna that has gain expressed in DBI looks like it has about 3 DB more gain than one in DBD, but produces the same results. compare apples to apples. If the manufacturere does not specify, it is probably the unit that gives them the most favorable numbers, even though the actual performance may be the same as an antenna with lower numbers i.e. dbd. In evaluating antenna systems, the three simple rules are bigger, higher and farther away from other objects. Either antenna should do you well. If you are interested in one specific city or two in the same direction, get a beam rather than a discone. The discone has advanteges in bandwidth but not in gain.

Answer 2

Do NOT PURCHASE the antennas your list in your link.



They are JUNK, JUNK, JUNK. STAY AWAY, STAY AWAY!



Discones, do NOT PROVIDE gain ever! Along with the junky RG58 cable included.



DO NOT PURCHASE EITHER OF THESE. JUNK!



You need to purchase quality equipment to ensure reception over long distance at 800MHz.



You need good cable.



LMR400 or equal

800MHz GAIN ANTENNAS



A good start would be:

http://www.antenna-theory.com/basics/gain.php



The reason you get the systems sometimes is due to propagation.



http://en.wikipedia.org/wiki/Radio_propagation



Weather, night v. day can all effect frequencies and their propagation.



Are all the systems in one direction?



The look at possibly using a yagi.



If you need local and remote then an omni is a better choice:

http://www.rfwiz.com/Comtelco/ComtelcoBase2.htm



Specificaly: BS800SN-A



Cable:

http://www.rfwiz.com/Comtelco/ComtelcoAcc2.htm



Look at the chart at the bottom and you can see the loss figures, higher numbers here are BAD, VERY BAD.



The LMR400 and 9913 cables are 3.9 and 4.2db in loss at the frequencies your interested in. The others are anywhere from 1.5X to 10X that. That can make the difference between hearing a system and not hearing a system.

Answer 3

the difference is 5.12–2 = 3.12 dB

In power, that is about twice as much power picked up.



I'd go with the higher gain antenna, and mount it as high as possible. Is there a reason why the higher gain antenna can't be mounted as high as the other one?



"I know I'm getting the signal" NO, you are not getting the signal. The clouds and/or the snow caused reflections, and at that time, you did get a signal. When the conditions are not optimal, the signal is not there!



You can't "draw in" a non-existant signal.



.

Answer 4

Higher gain antennas are often more directional. If all of your signals come from one direction (a tower in town?), the higher gain will be better. If the towers are scattered all around you, the lower gain MAY be a better compromise choice.

Answer 5

yes the 5.12 Db would pick up better but it depends on the frequency you are trying to listen to, you may be picking up skip and the band and the width would need to be known in order to advise you better. here is a ham radio web site you can check out and even get help building your own

http://www.hamuniverse.com/antennas.html

Answer 6

u shud go for the 5.2 dB antennae wid the shorter arm . coz even in a transmission area where signal attenuation is greater ur higher gain(5.2 db) antennae will be able to catch remote signals!