On 6/24/2020 9:03 AM, Dionísio de Carvalho wrote:
hi everybody
This is my fisrt message here. I am pretty new in the SDR world.
I am intended to develop a Radar with BladeRF2.0 from Nuand.
Is anybody in this boat?
I have some start questions that I will be grateful for any help:
- How can I sweep the Frequency at osmocom-sink? any idea?
- How can I figure out the TX power? I am trying to measure an antenna
S21 parameter!
thanks for any help
Att
Dionisio Carvalho
Sao Paulo University - Brazil
It is not easy to get a valid measurement of antenna gain or radiated
power. It is easier to design the antenna according to a published
formula (i.e., plans) and use the gain figures provided by the
originator. Be careful to observe whether the gain figure is in
reference to isotropic or to a dipole. A dipole has 2.1dB greater gain
than isotropic.
(An isotropic radiator is a theoretical point-source that radiates
in all directions--all points along a sphere surrounding it.
Professional antenna engineers use the isotropic source as a
reference point; radio amateurs tend to use a dipole as their reference
value.)
Now, measure the power out of your transmitter, with an appropriate
power meter--a lab meter for power levels up to about 10mW (+10dBm) or
a Bird or other higher-power meter for levels greater than +10dBm.
(A lab meter can be used with suitable fixed attenuators of known
value. Be careful not to overload the lab meter!)
Then calculate the effective radiated power: RF power from the
transmitter times the gain of the antenna. Use the same measurement
units (db, dbm, Watts, numerical gain or dB gain, etc.) to find the
ERP--effective radiated power.
Values in dB or dBm are ADDED, not multiplied!
--doug, WA2SAY, retired RF engineer
