Antennas
Objective
To ensure each patch antenna can sufficiently transmit and receive enough RF power within the 915 MHz ISM frequency band.
Proof of Concept
Calibrate port 1 of the Nano VNA from 800 MHz to 1000 MHz with 5 segments which will give you 505 points. Once the VNA is calibrated connect the patch antenna and perform a sweep while graphing the S11 Return Loss.
Pass criteria: 917 MHz - 928 MHz Return Loss < -3 dB
Fail criteria: 917 MHz - 928 MHz Return Loss > -3 dB
Methods
Need to ensure that the antenna can sufficiently transmit and receive RF power within the 915 MHz ISM frequency band. We began this test by performing a 1 port calibration such that the calibration plane was established at CH0 of the VNA for a frequency range of 800 MHz to 1000 MHz with 5 segments of 505 points. We then measured each antenna’s performance by connecting each of the antennas to port 1 and performing a frequency sweep while graphing the S11 Return Loss. The return loss of each antenna in the 915 MHz band resulted in less than -3.
Results
Our ideal return loss for all of the antennas would be negative infinity because that would mean 100% of the RF power inputted into the antenna is received and 0% is reflected back. However, this is nearly impossible to achieve, and we chose -3 dB return loss as our passing criteria because it means that half of the RF power is being received in the antenna and the other half is being reflected. After observing our results, we found that all antennas except antenna 4 passed this test. Antenna 4 did not pass because the measured return loss was 0 dB; we think this occurred as a result of a loose connection or defective element between the cable and the SMA connector attached to the antenna. The findings from this test also inspired us to specifically select 928 MHz as our frequency of operation because it had the lowest return loss compared to the alternate frequencies we have been considering in the 915 MHz band (917 MHz, 920 MHz, and 925 MHz). Out of all these frequencies, 928 MHz proved to be the optimal frequency since the measured return loss of each antenna was below -10 dB, meaning that 90% of the RF power is inputted into the antenna and only 10% is reflected back.
Antenna 1
![1.png](https://static.wixstatic.com/media/d427e6_7d0c804e614e483b82e9c3591767e7f8~mv2.png/v1/fill/w_834,h_743,al_c,q_90,usm_0.66_1.00_0.01,enc_auto/1.png)
Antenna 1 Results
Antenna 2
![2.png](https://static.wixstatic.com/media/d427e6_f1f5e827a3bf468490edbd0af3798d5c~mv2.png/v1/fill/w_834,h_742,al_c,q_90,usm_0.66_1.00_0.01,enc_auto/2.png)
Antenna 2 Results
Antenna 3
![3.png](https://static.wixstatic.com/media/d427e6_685d1e7f377043bd8da4105f31cffab3~mv2.png/v1/fill/w_834,h_742,al_c,q_90,usm_0.66_1.00_0.01,enc_auto/3.png)
Antenna 3 Results
Antenna 4
![4.png](https://static.wixstatic.com/media/d427e6_72a5d53a483d401db77fd6f079a1e4e2~mv2.png/v1/fill/w_834,h_742,al_c,q_90,usm_0.66_1.00_0.01,enc_auto/4.png)
Antenna 4 Results
Antenna 5
![5.png](https://static.wixstatic.com/media/d427e6_b483698017e94d7489c2a6d2de8e88b6~mv2.png/v1/fill/w_834,h_742,al_c,q_90,usm_0.66_1.00_0.01,enc_auto/5.png)
Antenna 5 Results
Antenna 6
![6.png](https://static.wixstatic.com/media/d427e6_5f3a0f4f34944d4186c5a5ae1060ac93~mv2.png/v1/fill/w_834,h_742,al_c,q_90,usm_0.66_1.00_0.01,enc_auto/6.png)
Antenna 6 Results
Images
Antenna 1
![IMG_0221 (1).jpg](https://static.wixstatic.com/media/d427e6_e68f25a9110d44eb8e1d77807d04e5c5~mv2.jpg/v1/crop/x_0,y_272,w_3024,h_3303/fill/w_834,h_911,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/IMG_0221%20(1).jpg)
All Antennas
All Antennas
All Antennas
All Antennas Set Up
Antenna 4
Antenna 1 Set Up
![IMG_0222 (1).jpg](https://static.wixstatic.com/media/d427e6_6dbad2e774e34c38989ead6af9affcb3~mv2.jpg/v1/fill/w_626,h_834,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/IMG_0222%20(1).jpg)
![IMG_0223 (1).jpg](https://static.wixstatic.com/media/d427e6_4d297afb93db40ff91a275589590e0fc~mv2.jpg/v1/fill/w_626,h_834,al_c,q_85,usm_0.66_1.00_0.01,enc_auto/IMG_0223%20(1).jpg)
![IMG_0276 (1).jpg](https://static.wixstatic.com/media/d427e6_3969606740bb41f4b8363bc477c4879c~mv2.jpg/v1/crop/x_746,y_766,w_2822,h_1532/fill/w_761,h_413,al_c,q_80,usm_0.66_1.00_0.01,enc_auto/IMG_0276%20(1).jpg)
Broken Antenna 4