Visina Antena
Faktori koji uticu na visinu antene i korine informacije prilikom planiranja wireless konekcije

Antenna Height Requirements for Outdoor Links

The height of an antenna depends on many factors:

Line of Sight

Add these values to find the Antenna Height.

Distance between the sites: Earth curvature, the longer the link, the higher the antenna needs to be. (This relation is not proportional) See Table.

The Fresnel Zone: This is a electromagnetic phenomenon, where light or radio signals get diffracted or bent from solid objects near their path. See Table showing the 60% of Fresnel Zone Values (Accepted clearing on path). Add this to the Earth curvature height.

Objects in the path: At a frequency of 2.4 GHz, you need a clear line of sight (LOS). Tree tops will reflect or ground the signal. The theory is that the height of the tallest object in the path of the signal should be added to the Fresnel Zone and Earth Curvature clearance heights. In your case, you should have to check the height of the trees, hills, buildings or any object on the link path and add this to the measurement for the total of the tower height.

The above three conditions make up the Radio Line of Sight. See Table:

Table

As mentioned before, this is theoretical data and there are many cases of customers with working links, with LOS (line of sight) just a few feet over the top of obstacles on their path. We just want to emphasize the need for clear line of sight. Make sure there are no trees in the way. We recommend that the height of the tower should be the minimum of the Earth Curvature plus Fresnel Zone clearance height, making sure that this height is at least 10 feet above the top of any obstructing object…before you start testing the link.

dBm to Watts Conversion Chart

dBm	Watts	dBm	Watts	dBm	Watts
0	1.0 mW	16	40 mW	32	1.6 W
1	1.3 mW	17	50 mW	33	2.0 W
2	1.6 mW	18	63 mW	34	2.5 W
3	2.0 mW	19	79 mW	35	3.2 W
4	2.5 mW	20	100 mW	36	4.0 W
5	3.2 mW	21	126 mW	37	5.0 W
6	4 mW	22	158 mW	38	6.3 W
7	5 mW	23	200 mW	39	8.0 W
8	6 mW	24	250 mW	40	10 W
9	8 mW	25	316 mW	41	13 W
10	10 mW	26	398 mW	42	16 W
11	13 mW	27	500 mW	43	20 W
12	16 mW	28	630 mW	44	25 W
13	20 mW	29	800 mW	45	32 W
14	25 mW	30	1.0 W	46	40 W
15	32 mW	31	1.3 W	47	50 W
Power Measurement Units dBm - decibels relative to one milliwatt dBW - decibels relative to one Watt			Gain Measurement Units dBi - decibels relative to an isotrope dBd - decibels relative to a dipole