[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

*Subject*: Re: [amsat-bb] Can anyone clarify dBic?*From*: "Pieter Ibelings" <elpieter@xxxxxxxxxxx>*Date*: Tue, 12 Jun 2001 15:32:24 -0400

Howard, I think you are right. The two 10 dBi antennas will produce 10dBic when orthogonal and phased orthogonal. Now that you have made circular polarization using two antennas orthogonal to each other, it is clear to see how the average power goes down by 3dB when you only use a single antenna. So if you receive a circular signal with a linear antenna you get 3dB less on average because you only get the vertical or horizontal component of the circular signal. Since the vertical component is Sin(a) and the horizontal is Sin(90-a) they both carry equal average energy. Getting rid of one drops 3dB. Now, if the signal is elliptical and it no longer follows the parametric equation v=sin(a) and h=cos(a) then you can have a lot more than 3dB drop from elliptical to linear. Remember than "really" elliptical means linear. I think this all makes sense. It's been a long day. Pieter ----- Original Message ----- From: "Howard Long" <howard@howardlong.com> To: <amsat-bb@AMSAT.Org> Sent: Tuesday, June 12, 2001 2:47 PM Subject: [amsat-bb] Can anyone clarify dBic? > A fly in the ointment for my understanding when calculating EIRP is whether > your antenna gain is dBi (for a linear antenna) or dBic (for a circularly > polarized antenna). > > Here's my understanding... > > There's potentially up to a 3dB _loss_ directly pointing a linear antenna at > a circular antenna compared to directly pointing circular to circular (of > the same sense of course). My understanding is that if you correctly phase > two, say, 10dBi linear antennas mounded perpendicularly to each other with > the boom at the axis, you get a 10dBic gain circular antenna. > > Perhaps someone will confirm or correct me on this simplistic view. > > 73 Howard G6LVB > > ---- > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA. > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org > ---- Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA. To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

**References**:**Can anyone clarify dBic?***From:*Howard Long

- Prev by Date:
**WISP QUESTION UNKNOWN PID** - Next by Date:
**Re: ERP on V and L for AO-40??** - Prev by thread:
**Can anyone clarify dBic?** - Next by thread:
**Re: Can anyone clarify dBic?** - Index(es):