# Design of 45 degree slant polarizer

1. ## Design of 45 degree slant polarizer

can anyone provide any design reference for a 45 degree slant polarizer? thanks in advance.

2. ## Re: Design of 45 degree slant polarizer

can anyone provide any design reference for a 45 degree slant polarizer?
Are you talking about optical polarisers? For the visible range of the EM spectrum? Using glass slide plates?

3. ## Re: Design of 45 degree slant polarizer

i meant antenna polarizer to change the polarization of the antenna from linear or circular polarization to slant polarization.

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4. ## Re: Design of 45 degree slant polarizer

i meant antenna polarizer to change the polarization of the antenna from linear or circular polarization to slant polarization.
I do not get it.

The orientation of the antenna determines the component (horizontal, vertical or 45deg) that will be received. If the main dipole component is oriented at 45deg, it will receive both horizontal or vertical polarized signals.

For circular polarization you will need two dipoles (at 90deg) that will be out of phase by 90deg).

Or, do you want to convert a linearly polarised signal to a circularly polarised one? A linearly polarised signal will be received by a circularly polarised antenna but 1/2 the signal will be lost.

Similarly, if you orient the antenna at 45deg with respect to the signal (horizontal or vertical), there will be also some signal loss.

Or, did I not understand the question?

5. ## Re: Design of 45 degree slant polarizer

Originally Posted by c_mitra

The orientation of the antenna determines the component (horizontal, vertical or 45deg) that will be received.
i have a monopole antenna with a fixed orientation that's vertically polarized. i want to change the polarisation to slant(45 degree). is it possible to change the polarisation without changing the orientation? if so, can a polarizer be used for that?

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6. ## Re: Design of 45 degree slant polarizer

i have a monopole antenna with a fixed orientation that's vertically polarized....
I hope I understand the question.

If the signal is vertically polarised and your antenna is also similarly oriented (the dipole is vertical), it will receive at max efficiency.

The same antenna will receive all horizontally polarised signals will 0 efficiency (no reception). And all signals with slanted polarization with reduced efficiency.

Similarly for horizontally polarised signal and horizontal dipole antenna.

An antenna for a circularly polarised signal need two dipoles separated by some distance (depends on the wavelength). A left circularly polarised signal will be received by a corresponding antenna. It will not receive a right circularly polarised signal.

Signals (say one polarised left circularly) can change their polarisation after reflection (left circularly becomes right circularly polarised) and will not be received by the antenna (say designed for the left circularly signal).

If your dipole is oriented 45 towards horizontal (and vertical), it will receive both horizontally polarised an vertically polarised signals (but with reduced factors). But you cannot change the polarization of the incident signal.

By the way, if you have a giant reflector and if you can place it wisely, the incident signal can get reflected and change its polarisation. But that is not the question, right?

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7. ## Re: Design of 45 degree slant polarizer

Originally Posted by gayathrim
i have a monopole antenna with a fixed orientation that's vertically polarized. i want to change the polarisation to slant(45 degree). is it possible to change the polarisation without changing the orientation? if so, can a polarizer be used for that?
I believe the answer is no.
However to be noted is that signal loss is 3 dB (half-power) where a vertical polarised signal is being received by a 45deg slant antenna.

8. ## Re: Design of 45 degree slant polarizer

Originally Posted by kripacharya
I believe the answer is no.
However to be noted is that signal loss is 3 dB (half-power) where a vertical polarised signal is being received by a 45deg slant antenna.
sorry for the ambiguity. the receiving signal is 45 degree polarised. the receiver monopole antenna is vertically oriented and hence the polarisation. the orientation is fixed. can a polariser be used to change the polarisation of the received signal

10. ## Re: Design of 45 degree slant polarizer

the receiving signal is 45 degree polarised. the receiver monopole antenna is vertically oriented...
You are still ambiguous. If the incident signal is 45 deg pol with respect to horizontal, and your antenna is vertical, you will not get anything.

On the other hand, if the signal is 45 deg polarised w.r.t the vertical plane, you will still get some signal.

You say monopole antenna? Common antenna are dipole- it catches two ends of the same signal.

11. ## Re: Design of 45 degree slant polarizer

Originally Posted by c_mitra
You are still ambiguous. If the incident signal is 45 deg pol with respect to horizontal, and your antenna is vertical, you will not get anything.

On the other hand, if the signal is 45 deg polarised w.r.t the vertical plane, you will still get some signal.

You say monopole antenna? Common antenna are dipole- it catches two ends of the same signal.

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12. ## Re: Design of 45 degree slant polarizer

Originally Posted by c_mitra
if the signal is 45 deg polarised w.r.t the vertical plane, you will still get some signal.
so is there a way to improve the efficiency in this case without changing the orientation of the receiving antenna?

13. ## Re: Design of 45 degree slant polarizer

Why aren;t you getting it ??

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Originally Posted by c_mitra
You are still ambiguous. If the incident signal is 45 deg pol with respect to horizontal, and your antenna is vertical, you will not get anything.

On the other hand, if the signal is 45 deg polarised w.r.t the vertical plane, you will still get some signal.

You say monopole antenna? Common antenna are dipole- it catches two ends of the same signal.
Please clarify how 45 from vertical is different from 45 from horizontal. Is this some sort of 5-dimensional problem ???

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