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#1
October 29th 20, 07:30 PM
posted to rec.radio.amateur.antenna
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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 ========================== |
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#2
October 30th 20, 08:14 AM
posted to rec.radio.amateur.antenna
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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. |
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#3
October 30th 20, 09:06 AM
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TV antenna on 698 MHz
Ok, i will check for. Thank you. Giovanni |
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#4
October 31st 20, 08:10 AM
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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 |
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#5
October 31st 20, 08:40 AM
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TV antenna on 698 MHz
wrote:
Hi. I checked. The signal on 698 MHz is there. Which country is that? |
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#6
October 31st 20, 08:56 AM
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TV antenna on 698 MHz
Italy
Which country is that? |
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#7
October 31st 20, 09:15 AM
posted to rec.radio.amateur.antenna
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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! |
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#8
October 31st 20, 12:16 PM
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TV antenna on 698 MHz
Ok, thank you.
I will change the frequency. Giovanni |
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