TV antenna on 698 MHz
 

Hello. I have designed an antenna with the 4nec2 program.
It is a 698 MHz Bow Tie antenna. The simulations confirm excellent results:

- Impedance 75 Ohm
- SWR 1:05
- Gain 10 dBi.

Really building the antenna, it doesn't work, even though I have retuned the TV. The signal is 0.

On the other hand, by building a dipole tuned to 698 MHz (half wave) the TV works perfectly.

Can you please tell me why?
Below is the antenna source listing, for the 4nec2 program.

Thank you all.
Giovanni Di Maria


==========================
CM
CE
SY X=0.1964
SY ALTEZZA=1
SY Y=0.2307
SY P1=0.01
SY RAGGIO=1.e-3
GW 1 3 -P1 0 ALTEZZA P1 0 ALTEZZA RAGGIO/2
GW 2 11 P1 0 ALTEZZA X 0 ALTEZZA+Y RAGGIO
GW 3 11 P1 0 ALTEZZA X 0 ALTEZZA-Y RAGGIO
GW 4 11 -P1 0 ALTEZZA -X 0 ALTEZZA-Y RAGGIO
GW 5 11 -P1 0 ALTEZZA -X 0 ALTEZZA+Y RAGGIO
GE -1
GN 1
EK
EX 0 1 2 0 0 0 0
FR 0 0 0 0 698 0
EN
==========================

TV antenna on 698 MHz
 

wrote:
Hello. I have designed an antenna with the 4nec2 program.
It is a 698 MHz Bow Tie antenna. The simulations confirm excellent results:

- Impedance 75 Ohm
- SWR 1:05
- Gain 10 dBi.

Really building the antenna, it doesn't work, even though I have retuned the TV. The signal is 0.

On the other hand, by building a dipole tuned to 698 MHz (half wave) the TV works perfectly.

Can you please tell me why?

Probably there is no TV on 698 MHz anymore (or it is going to be shut
down soon). Check the frequency of the transmission.

Of course that would not be the reason for 0 signal but it will not
perform optimally. For 0 signal check for connection faults.

TV antenna on 698 MHz
 

Ok, i will check for.
Thank you.
Giovanni

TV antenna on 698 MHz
 

Hi.
I checked.
The signal on 698 MHz is there.
With a half wave tuned dipole it works perfectly.

What is the criterion for designing TV antennas with 4nec2?
The project works and the parameters are all OK, but in practice the antenna does not work.

Thanks.
Giovanni

TV antenna on 698 MHz
 

wrote:
Hi.
I checked.
The signal on 698 MHz is there.

Which country is that?

TV antenna on 698 MHz
 

Italy



Which country is that?

TV antenna on 698 MHz
 

wrote:
Italy



Which country is that?

Services on channel 49 and above should have been discontinued by
june this year to vacate the space for mobile communication (4G/5G).

Maybe Italy has been lagging behind and has asked for the possible 2 year
extension of that date. But for sure that TV station is going to move!

TV antenna on 698 MHz
 

Ok, thank you.
I will change the frequency.
Giovanni