Categories
Statistics
Flag Counter
Since 08.08.2014
Counts only, if "DNT = disabled".

Your IP is 54.145.148.103
ec2-54-145-148-103.compute-1
Info
Valid HTML 4.01 Transitional Creative Commons Lizenzvertrag
rss
เราจะทำแบบวิศวกรผู้ยิ่งใหญ่
We love the King
Your valuable opinion :
4.5 stars

Avg. 4.88 from 25 votes.



Antenna_Selection_Guide.php   8452 Bytes    07-08-2015 18:25:21


Antenna Selection Guide




People often ask for GSM-Antenna, WiFi Antenna or XYZ Antenna. Unfortunately the answer is always : "There is no such thing" (and my search-engine shows no results), as all names describe a service. The antenna however does not care about your service nor modulation or power. Instead, antennas are classified regarding other properties like gain, bandwidth or radiation pattern. Our list suggests antenna types with respect to their relative position. The question here is always : Is the position fixed or is the sender / receiver moving around. An antenna does not care if used as receiver or transmitter. (First iteration ;-)




Scenario #1 : Sender fixed position, Receiver fixed position





This is the case when you watch television or radio at home (unless you live in a caravan :-)
In that case we suggest you use an antenna with a small aperture angle, pointing towards the Sender (Transmitter). Depending on the distance and frequency, you need more or less gain. More gain is necessary for large distances and for higher frequencies, as the radiowave is attenuated more. The following designs may be suiteable for that case :

Antenna TypeBandwidthConstructionCost
Yagi Uda Antenna small, ~ 10%easymedium
HB9CV Antenna small, ~ 4%easylow
LPDA broadbandeasymedium
Parabolic antenna smalladvancedhigh
Cantenna smalleasylow

Or anything else with a small aperture angle.




Scenario #2 : Sender fixed position, Receiver moving around




GSM Antenna @ ETH Hoenggerberg

This is the case when you listen radio in your car or when you make a call with your mobilephone. In that case we suggest you use an antenna with a large aperture angle, preferrably an omnidirectional design. This will make sure, that your signal strength is independant of your position (just getting smaller with increased distance). The following designs may be suiteable for that case :

Antenna TypeBandwidthConstructionCost
λ/4 Groundplane smalleasylow
Discone broadbandeasyhigh
J-Pole smalleasylow

Or anything else with an omnidirectional characteristic.




Antenna Gain versus Omnidirectivity




An isotropic radiator is a theoretical point source of electromagnetic or sound waves which radiates the same intensity of radiation in all directions. It has no preferred direction of radiation. It radiates uniformly in all directions over a sphere centred on the source. Isotropic radiators are used as reference radiators with which other sources are compared. Wikipedia Isotropic radiators have no gain.

The gain arises, when the pattern is no longer uniform in all directions. We may understand the gain as the ratio of radiation angle with respect to a sphere. The smaller the angle, the more power may be transmitted in one direction. The more "Gain" we have.




✈ Share your thoughts


✈ Nothing more to be seen below this point ? Maybe your browser blocks the facebook iframe.
The webmaster does not read the comments regularly. Urgent questions should be send via email.








 
t1 = 3913 d

t2 = 379 ms

★ ★ ★  Copyright © 2006 - 2017 by changpuak.ch  ★ ★ ★

PRchecker.info Impressum