UHF signals by the MOON .....  on 437 Mhz , info to received it ? - Page 1
Forum section: electronics / rf-microwave

author: 1enry1
author_rank: Contributor
timestamp: February 04, 2024, 08:56:24 pm
content: Probe on the moon and cw signals!Japan on the moon, the Slim mission touched the soil !!!The Japanese radio amateur station JQ1ymg is entrustedQRG437.410 MHz, 1 Wattwith CW emission !!!You canuse a normal radio amateur transceivereWhat antenna is used incircular polarization(and what size?) or aparable diskand what type and sizes?Thanks for the info, 73

author: MarkT
author_rank: Frequent Contributor
timestamp: February 04, 2024, 09:56:40 pm
content: 70cm band helical. Something like this?https://www.wimo.com/en/helix-70. You need to check whether RH or LH helix.

author: RoGeorge
author_rank: Super Contributor
timestamp: February 05, 2024, 07:34:33 am
content: Quote from: 1enry1 on February 04, 2024, 08:56:24 pmAre you sure it can be received with a DIY antenna and a ham transceiver?Asking because these guys were mentioning a 25 meters dish radiotelescope to receive the 437.410 MHz/1W station from the Moon:https://destevez.net/2024/01/trying-to-decode-lev-1/Then, this comment in the above linked article:Quote

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: February 05, 2024, 07:31:27 pm
content: Whereas low earth orbiting satellites are easy to receive on simple equipment due to only being several hundred to about 1000km up, the moon is nearly 400 000km away.This means there's a big path loss to overcome.Which needs a high gain antenna, quiet location and good receiver.More info:https://www.fcc.gov/help/public-safety-tech-topic-17-propagation-characterizationhttps://www.pasternack.com/t-calculator-fspl.aspx?fbclid=IwAR1qbJEB1AToS0mBC_VS4m3PLhPzkjQN4t8xZohTNTqkfMvTO8A3y5kGY60https://destevez.net/2024/01/trying-to-decode-lev-1/?fbclid=IwAR1_vfdLac-fM-d2vjuv3Du6xu901cedsE36MHmkcNVKlxS4lI6V9f82Nn8

author: MarkT
author_rank: Frequent Contributor
timestamp: February 05, 2024, 08:47:52 pm
content: But not as demending as moon bounce... (EME)

author: glenenglish
author_rank: Frequent Contributor
timestamp: February 08, 2024, 03:27:04 am
content: it's at least 40dB easier than moonbounce .1W into 3dBi will be -163dBm.so with a RBW of 500Hz, and a 20dBi antenna, ( 25 elements maybe or a 2m dish) should be quite audible.SHould be visible on a waterfall with 10dB less than that.There will be substantial doppler..... but, you can track it easy enough and drive the radio frequency directly to account for the doppler, its all calculable.

author: radiolistener
author_rank: Super Contributor
timestamp: February 10, 2024, 06:33:11 am
content: Quote from: 1enry1 on February 04, 2024, 08:56:24 pmThe disatance between Moon and Earth surface is about 384400 km, so back and forth distance is about 768800 km.At 437.410 MHz the free path loss is about 203 dB!If you're using good Yagi–Uda antenna with 20 dBi gain on receiver and on transmitter, the signal loss will be more than 203-20*2=163 dB.Using 1W transmitter you have 30 dBm power. So the receiver will get less than +30-163=-133 dBm power. This is about 0.05 uV.It will be very hard to detect the signal which is less than 0.05 uV.So, it's better to use 100 W transmitter, which is 50 dBm power. It will give you 20 dB gain in comparison with 1 W, so your receiver will get +50-163=-113 dBm. Which is about 0.5 uV. This is much better and you can detect it with a good receiver.If you want to receive transmitter placed on the Moon, the distance will be twice shorter 384400 km and free path loss will be 197 dB. The difference is just 6 dB.As you can see, you're needs to use pretty large antennas with high directivity in order to achieve high enough antenna gain. Otherwise you will be unable to recevie something from the Moon. Just because free path loss is about 200 dB.

author: 1enry1
author_rank: Contributor
timestamp: February 11, 2024, 02:06:16 pm
content: wow ...... GREAT ! thanks to all ! 73