dipole and yagi antenna

yagi uda signal strength increases

Hi everyone I would like to ask some basic questions about dipole antenna and yagi uda antenna
I hope to get answers theoretically
( GAIN, FREQUENCY, HIEGHT, back to front ratio, resistance reactance, beam width, side lobes)

My questions are
1- How can we do a relation between these parameters I mean (frequency increase gain increase?
Height increase gain increase such like that
2- Why they prefer half wave dipole antenna than others is it coz of the current distribution on the wire or coz of the side lobs
3- How does the side lobs effect on the wire (the side lobes increase the signal is becoming worst?

Yagi antennas
1-Is it the same relations’ as the dipole
2- Why I can’t find in the books formulas how to find the dipole lengths or directors all what I find some dates or appendix but I need to see formulas
3-what is the effect of increasing the directors in the characters
4- Changing the spaces between the directors how does it effect
5- When we use V antenna in homes how does the angles effect why when we change the angles it effect on the signal
Lot of questions but if I get the answers I will be very happy.. I know some friends will say go and study ) or will send me some books or websites, but really when a person gives me answer I feel that he is like a teacher gives a simple and short answers ….thanks for every one

yagi antnna formula

Read any of the books below:

- Antenna engineering handbook, Johnson-Jasik
- Antenna theory, Balanis

Have a look at the attached figure which gives the general formula for calculating gain with respect to antenna size.
As frequency(f) increases wavelength(λ) decreases, as seen from below formula Gain is inversely propotional to wavelength,so as frequency increases gain also increases.

Also gain is directly propotional to Area of the aperture so as the area of the antenna increases gain also increases.

Note that Gain is inversely propotional to Beam width.

In Yagi Antenna directors are used to direct the beam in the required direction as you increase the number of directors beam will be confined to particular direction which increases the gain of the antenna in that direction.

As sidelobe level increases, your signals will be splitted in the unwanted direction and signal strength at the required direction will be less.