Question

One of AT&T's core 4G LTE bands is band 2, which operates at 1900 MHz. If we made a quarter wave monopole antenna designed for this band, what should the length of the antenna be? AT&T also owns band 5 (850MHz), also used for LTE. Which of these two bands (band 5 vs band 2) would provide higher data rates, and why? Comparing GHz vs Khz frequency radiation for radio communication, what is one 1 disadvantage of the higher frequency radiation? Why do we limit our exposure to UV or X-ray radiation? (you may refer to lecture video or look this up online)

Answer 1

Answer 3->  

Comparicion behoeen GHz & KHz low frequery khz Highe frequeng (microve Ghz frequery 125-134 KHz 2.4, SI8 GH2 tag expeñse · Reader cost High low ~30 cm High High more fuan work range (max) Data Rate Low High High latea fereme low • Advautages ference lo w wide acces low environmeaf absorphon range Acces control, Animal fD, securiny , Common Applicahion industiny

Disadvantages of Higher frequency->

1. More expensive components.

2.Higher atmospheric loss.

3.Higher components losses,lower output power from active devices.

Answer 4->

Some UV exposure is essential for good health. It stimulates vitamin D production in the body. In medical practice, one example is UV lamps can be used for treating psoriasis (a condition causing itchy, scaly red patches on the skin).

Excessive exposure to ultraviolet radiation is associated with different types of skin cancer, sunburn, accelerated skin aging, as well as cataracts and other eye diseases. The severity of the effect depends on the wavelength , intensity, and duration of exposure.

UV radiation is invisible and therefore does not stimulate the natural defenses of the eyes. Workers must use eye and skin protection while working with UV radiation sources which present the potential of eye harmful exposure. The selection of eye protection depends on the type and intensity of the UV source. UV radiation is easily absorbed in a variety of materials. Shielding is usually easy to design. Mercury lamps and metal halide lamps have an outer glass cover to stop UV radiation, and are designed such that if the outer glass is broken, the lamp ceases to function.