Question E9H07:
What is the function of a Beverage antenna’s termination resistor?  

Choices:  
A: Increase the front-to-side ratio  
B: Absorb signals from the reverse direction  
C: Decrease SWR bandwidth  
D: Eliminate harmonic reception    

Correct Answer is  B: Absorb signals from the reverse direction  

Why the correct answer is correct (B)
- A Beverage is a traveling-wave receive antenna. A resistor at the far end is used to terminate the wire in approximately its characteristic impedance so the wave does not reflect.
- With a proper termination, energy arriving from the “reverse” direction is absorbed in the resistor instead of being re-radiated back along the wire, which suppresses response from the rear and makes the antenna unidirectional.

Key idea:
- The termination creates a matched load so the reverse-traveling wave is dissipated as heat, not reflected.

Why the other choices are incorrect
- A: Increase the front-to-side ratio  
  The termination mainly improves front-to-back (reverse suppression), not front-to-side. Side response is mostly set by length, height, and orientation.
- C: Decrease SWR bandwidth  
  Beverage antennas are typically used for receiving; SWR is not the design focus. The termination stabilizes impedance, but its function is pattern control, not narrowing SWR bandwidth.
- D: Eliminate harmonic reception  
  The resistor does not act as a filter for harmonics; it controls direction by absorbing reverse waves.

Useful formulas and rules of thumb
- Choose the termination to match the antenna’s characteristic impedance:  
  $$R_T \approx Z_0 \quad (\text{often } 400\text{–}600\,\Omega)$$
- Reflection coefficient at the termination:  
  $$\Gamma = \frac{R_T - Z_0}{R_T + Z_0}$$
  If $R_T = Z_0$, then $\Gamma = 0$, meaning no reflection and maximum reverse suppression (best front-to-back).
- Rule of thumb: Adjust $R_T$ (commonly 470–560 Ω) for best front-to-back on the band of interest. The antenna is most sensitive toward the terminated end.