In post How to calculate Fresnel Zone in Microwave System, talked about formula to calculate Link Budge, Fresnel Zone Clearance and Microwave Antenna height. This section discuss to calculate receive level of Microwave link for real sites.
Parameter
Site A
Site B
Base on Latitude and Longitude of both sites can calculate Path Length by Haversine formula: 0.25Km
Microwave Antenna height = Radius of First Fresnel Zone(m)+Obstruction Height(m)
Radius of First Fresnel Zone without obstacle between both stations F = 17.3x(D/4f)1/2
So we get F = 17.3x(0.25/(4x15))1/2= 1.11m
EIRP (Effective Isotropic Radiated Power) is the measured radiated power of an antenna in a specific direction. It is also called Equivalent Isotropic Radiated Power. It is the output power when a signal is concentrated into a smaller area by the Antenna. The EIRP can take into account the losses in transmission line, connectors and includes the gain of the antenna. It is represented in dB. Enter the transmitted power, cable loss and antenna gain to calculate the EIRP (Effective Isotropic Radiated Power).
EIRP = Ptx – Ltx + Gtx=1-1+36.8 = 36.8 dBm
After that we get Receive Level
Receiver Signal Level = EIRP – Lfs+ Grx – Lrx
Lfs = 32.4 + 20*log10 F + 20* log10 D = 32.4 + 20*log10 15000 + 20* log10 0.25 =103.88 dB
Receive Level = 36.8-103.88+36.8-1 = -30.1 dBm
Flat fade margin = Receive signal level – Receiver sensibility threshold = -30 - (-62) =32 dB
Finally, we get summary table as below.
Parameter
- Frequency Band(GHz): 15
- Transmitter Power (dBm): 1
- Receiver cable Loss (dB): 1
- Transmitter Cable Loss (dB): 1
- Transmit Antenna Gain (dBi): 36.8
- Receiver Antenna Gain (dBi): 36.8
- Receiver Sensibility Threshold (dBi): -62
- Path Length (km): ?
Site A
- Latitude: 11 34 17.04 N
- Longitude: 104 53 21.84 E
Site B
- Latitude: 11 34 11.32 N
- Longitude: 104 53 15.76 E
Base on Latitude and Longitude of both sites can calculate Path Length by Haversine formula: 0.25Km
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| Path Length |
Receive Level Calculation
1- Microwave Antenna Height of Both Sites
Radius of First Fresnel Zone without obstacle between both stations F = 17.3x(D/4f)1/2
So we get F = 17.3x(0.25/(4x15))1/2= 1.11m
- Site A Microwave Height = 21.89 + 1.11 = 23m
- Site B Microwave Height = 23.89 + 1.11 = 25m
2. Receive Level Both Sites
EIRP (Effective Isotropic Radiated Power) is the measured radiated power of an antenna in a specific direction. It is also called Equivalent Isotropic Radiated Power. It is the output power when a signal is concentrated into a smaller area by the Antenna. The EIRP can take into account the losses in transmission line, connectors and includes the gain of the antenna. It is represented in dB. Enter the transmitted power, cable loss and antenna gain to calculate the EIRP (Effective Isotropic Radiated Power).
EIRP = Ptx – Ltx + Gtx=1-1+36.8 = 36.8 dBm
After that we get Receive Level
Receiver Signal Level = EIRP – Lfs+ Grx – Lrx
Lfs = 32.4 + 20*log10 F + 20* log10 D = 32.4 + 20*log10 15000 + 20* log10 0.25 =103.88 dB
Receive Level = 36.8-103.88+36.8-1 = -30.1 dBm
3. Flat Fade Margin
Finally, we get summary table as below.
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