Transmitting / Receiving mode 1

[Mica188]

Hi,

Q. What is the set up for a transmitting antenna and the set up for a receiving antenna ? I know the proprities of a transmitting or a receiving antenna are the same but what is the different between an operating mode and a receiving mode?

Thanks,

Mica

 

[VEBill]

It is often stated that the principle of reciprocity means that an antenna can be used for either transmit or receive mode. It is essentially true, but there are a few practical differences:

1) A transmit antenna may have to deal with much higher power levels than a receive antenna.
2) Receive performance may be limited by Signal to Noise ratios (like HF) and thus antenna gain at the receive site might not provide any advantage (where the noise is arriving from the same direction as the signal). On the other hand, it will very likely help on the transmit end.
3) A transmit antenna may have more health & safety requirements associated with it.

The above is just background info.

Can you rephrase your question?

 

[Mica188]

Thanks, I want to know is if I see this equipement this is a transmitting antenna and vise versa. What do you mean by transmit antenna may have more " health & safety " requirements ?

Mica

 

[VEBill]

Canada has 'Safety Code 6' that provides very good guidance for installation of RF sources. Basically, certain transmitter systems emit sufficient RF power that there can be Health and Safety requirements.

Is your original question about how to install antennas, and is there any difference between receive and transmit installations ?

I'm still trying to understand the question.

 

[Mica188]

Thanks, Yes, sorry for misunderstand of the question. The question is the installations of the transmitting and receiving antenna. This is the question that I want to ask.

Thanks again,
Mica

 

[IRstuff]

The answer is no, unless you can tell the difference between a transmitter and a receiver simply by looking at it.

TTFN

 

[VEBill]

Most of the rules of thumb for installing antennas applies equally well to both receive and transmit antennas. How applicable those rules are depends on your particular application. For example, higher is generally better, but higher doesn't much matter for a satellite TV dish.

The only difference between receive and transmit antennas relates to the power being emitted from the transmit antenna and what it might do to other things (or people) in the area.

If you can provide some specifics, then there may be some free advice about how to install antennas.

 

[Mica188]

Thanks, I'm try to prepare a presentation to explain about what is an antenna so, the question is, if someone ask me what is the different between them. I have no answer, so that why I'am sking this.

Mica

 

[VEBill]

There is essentially no difference between a receiving antenna and a transmitting antenna. They are the same thing.

There are some debatable exceptions to the rule, for example an active antenna where (semantically at least) the 'antenna' (system) contains some active RF amplifier components that are designed for receive only. Examples of this are Satellite TV LNBFs, GPS antennas, HF 'Active Antennas', etc. None of these 'antennas' can be used for transmit purposes in their original state. Some will argue about which part of the 'antenna system' is the actual 'antenna' - it would be a fair point.

For the antenna element itself, no difference. Works as well (or as bad) for receive as it does for transmit.

Google 'reciprocity' and 'antenna' for details.


I still wonder about the difference if any between the virtually flat wavefront in the far field for an antenna system (like a Yagi) in receive mode, and the curved wavefront in the near field for the same antenna structure in transmit mode. I'm not totally convinced that they're perfecty equivalent (slight delta pattern). This is very likely just an issue with my understanding, but I still wonder about it...