You are right. J-Pole being basically an end fed half-wave vertical dipole, with a quarter wave matching section, there may not be much gain over dipole. 73
"2m antenna will also resonate on 70cm as third harmonic"........... Could you please explain this in detail, this was heard in EFHW or in long wire antenna, more useful it is clarified ..... thanks de VU3EHT
It is a common principle. 7 MHz center fed half wave dipole antenna will resonate on 21 MHz as 3/2 lambda antenna and we routinely work 21 MHz or 15m using 40m antenna. It will also resonate on other odd harmonics, but not on even harmonics (e.g. 14 MHz and 28 MHz). End Fed Half Wave Antenna resonates on all harmonics (odd and even). 7 MHz EFHW will resonate on 14 MHz, 21 MHz and 28 MHz. That is why it is popular for portable operations as you need not put up many antennas for multi-band operation. But the feedpoint impedance is high for EFHW and needs 49:1 matching transformer. Uplink frequency of Space Station is 145.990 MHz. Third harmonic is 437.97 MHz, which is near the downlink frequency of 437.800 MHz. That is how 2m antennas can receive downlink from Space Station, though best is having two directional antennas for VHF and UHF. 73
@johnsonstechworld Thanks for your crisp and clear description....... Now i understood why the EFHW is quite famous among all. If possible make a video of this topic briefly, it will be helpful as it is more interesting 🙏
Very well presented and explained. I know the J pole antenna and have built several but I still learned a lot from your excellent video, thank-you!
Glad it was helpful! 73 Jon, VU2JO
What is the gain of this antenna compared to a dipole? I'm assuming that this antenna also has a limited bandwidth just as a dipole.
You are right. J-Pole being basically an end fed half-wave vertical dipole, with a quarter wave matching section, there may not be much gain over dipole. 73
Can you make a video on multiband longwire antennas
Good suggestion. Shall plan one. 73 Jon, VU2JO
"2m antenna will also resonate on 70cm as third harmonic"........... Could you please explain this in detail, this was heard in EFHW or in long wire antenna, more useful it is clarified ..... thanks de VU3EHT
It is a common principle. 7 MHz center fed half wave dipole antenna will resonate on 21 MHz as 3/2 lambda antenna and we routinely work 21 MHz or 15m using 40m antenna. It will also resonate on other odd harmonics, but not on even harmonics (e.g. 14 MHz and 28 MHz). End Fed Half Wave Antenna resonates on all harmonics (odd and even). 7 MHz EFHW will resonate on 14 MHz, 21 MHz and 28 MHz. That is why it is popular for portable operations as you need not put up many antennas for multi-band operation. But the feedpoint impedance is high for EFHW and needs 49:1 matching transformer. Uplink frequency of Space Station is 145.990 MHz. Third harmonic is 437.97 MHz, which is near the downlink frequency of 437.800 MHz. That is how 2m antennas can receive downlink from Space Station, though best is having two directional antennas for VHF and UHF. 73
@johnsonstechworld Thanks for your crisp and clear description....... Now i understood why the EFHW is quite famous among all. If possible make a video of this topic briefly, it will be helpful as it is more interesting 🙏
Thank you very much. 73