Calculating Space Diversity Antenna height

[mohamad]

Dear all friends,
To calculate space diversity antenna height, ITU-R P.530-12 say: "the clearance of the lower antenna may be chosen to give about 6 dB of diffraction loss during normal refractivity conditions".

My question is: between which both of antenna I should calculate diffraction loss? between main antenna in site A and space diversity antenna in site B and viceversa? or between space diversity antennas in both sites?

Best Regards,

Mohamad

[RF engineer]

Dear all friends,
To calculate space diversity antenna height, ITU-R P.530-12 say: "the clearance of the lower antenna may be chosen to give about 6 dB of diffraction loss during normal refractivity conditions".

My question is: between which both of antenna I should calculate diffraction loss? between main antenna in site A and space diversity antenna in site B and viceversa? or between space diversity antennas in both sites?

Best Regards,

Mohamad

Hi
May be this would be helpful.
BR
RF

[firstmaxim]

Dear all friends,
To calculate space diversity antenna height, ITU-R P.530-12 say: "the clearance of the lower antenna may be chosen to give about 6 dB of diffraction loss during normal refractivity conditions".

My question is: between which both of antenna I should calculate diffraction loss? between main antenna in site A and space diversity antenna in site B and viceversa? or between space diversity antennas in both sites?

Best Regards,

Mohamad

Diffraction loss should be estimated between the lower antennas of the two sites. That would give the worst case figures.

Regards.

[byja]

Nope, it should be calculated for main antennas. To calculate it for space diversity antennas would give you too pesimistic results, which could result in using too big antennas.

But there's another issue here. You check clearance in two steps:
1. for k=1.33 you should have 100% F1 clearance
2. for k not exceeded for 99.9% of time you should have 60% or 70% F1 clearance.

K in 2. is determined based on path length alone, and it's usually between 0.6 and 0.9 depending on path length. If you have a problem with diversity antennas and point 1, then you almost certainly have a problem with main antennas and point 2.

[prle]

Dear all friends,
To calculate space diversity antenna height, ITU-R P.530-12 say: "the clearance of the lower antenna may be chosen to give about 6 dB of diffraction loss during normal refractivity conditions".

My question is: between which both of antenna I should calculate diffraction loss? between main antenna in site A and space diversity antenna in site B and viceversa? or between space diversity antennas in both sites?

Best Regards,

Mohamad

diversity antenna is only receiving antenna, so LOS between two diversity antenna means nothing, you should always check relations between main (Tx) antenna on one side, and two antennas on other side.

[googman]

in the name of allah

[cekerayam]

Hi,
a Document from E///

Tks

Dear all friends,
To calculate space diversity antenna height, ITU-R P.530-12 say: "the clearance of the lower antenna may be chosen to give about 6 dB of diffraction loss during normal refractivity conditions".

My question is: between which both of antenna I should calculate diffraction loss? between main antenna in site A and space diversity antenna in site B and viceversa? or between space diversity antennas in both sites?

Best Regards,

Mohamad

[firstmaxim]

Nope, it should be calculated for main antennas. To calculate it for space diversity antennas would give you too pesimistic results, which could result in using too big antennas.

But there's another issue here. You check clearance in two steps:
1. for k=1.33 you should have 100% F1 clearance
2. for k not exceeded for 99.9% of time you should have 60% or 70% F1 clearance.

K in 2. is determined based on path length alone, and it's usually between 0.6 and 0.9 depending on path length. If you have a problem with diversity antennas and point 1, then you almost certainly have a problem with main antennas and point 2.

"the clearance of the lower antenna may be chosen to give about 6 dB of diffraction loss during normal refractivity conditions". This means, there can be an allowance for an obstruction in the LOS of the diversity antenna. If one sees the fresnel kirchoff diffraction coefficient for height of obstacle above LOS. When this height is zero, the coeff value is zero. This translates to a diffraction loss of 6 dB.

Regards.