CRAC Class C (2025) — Questions 581–590

Loss attenuates the forward signal so less power radiates (A), and on receive the loss is ahead of the receiver, lowering the SNR (B). Loss does not by itself force SWR > 1 (C) nor distort the signal (D).

Water raises the dielectric constant and loss, and corrodes the conductors, increasing loss (A) and eventually causing opens (B). The velocity factor can never exceed 1 (C), and SWR is always ≥ 1 (D) — both are physically impossible, so they are wrong.

UV degrades the outer jacket; once it cracks, water enters and ruins the cable (A). UV is not an RF source and does not cause mixing, intermodulation, or heating of the cable (B/C/D are false).

Air dielectric gives very low loss but, being open to air, must be sealed against moisture ingress (A). It is not band-limited to 30 MHz, not high-loss, and works below freezing (B/C/D are wrong).

Coax loss (especially dielectric loss) increases with frequency (A). Characteristic impedance is set by geometry and is essentially constant (C is wrong); reflected power and SWR depend on the load match, not on frequency alone (B, D are wrong).

Air-dielectric rigid coax has the lowest dielectric loss of these choices, so it has the lowest loss at VHF/UHF (A). Twisted pair and flexible coax have higher loss.

The Type N connector is designed for high frequencies (up to several GHz) with low loss and good impedance control, so it is preferred above 400 MHz (A). The M/RS-213/DB-23 choices are not the appropriate HF/VHF-UHF connectors for this purpose.

Per the question's marked answer, the Type M connector is widely used in HF and VHF communication systems (A). The other descriptions — threaded/waterproof (B), bayonet quick- connect (C), and expensive microwave use (D) — are distractors for this item.

A vertical antenna radiates vertical polarization (E-field vertical, A correct) and is omnidirectional in azimuth — which is the H-plane — so the H-plane pattern is circular/omnidirectional (B correct). For vertical polarization the magnetic field is horizontal, not vertical (C wrong); the E- plane (vertical cut) is not omnidirectional (D wrong).

A horizontal dipole radiates horizontal polarization (E-field parallel to ground, A correct). The plane containing the element is the E-plane; for a horizontal dipole that plane is horizontal, and its pattern is the figure-8 (B correct). C is wrong (that is vertical polarization); D swaps the E/H planes (the H- plane of a horizontal dipole is the vertical cut, which is omnidirectional).